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General and administrative

$ 195,670

$ 184,360

$ 168,234

Cost of revenue:

Cost of services

^[1]

85,920

78,423

78,857

Depreciation — network

16,277

18,138

18,032

Total cost of revenue

102,197

96,561

96,889

Gross profit

93,473

87,799

71,345

Operating expenses:

32,372

32,053

30,042

Sales and marketing

39,553

36,098

32,945

Research and development

24,075

25,342

24,335

Depreciation and amortization

2,313

2,376

2,452

Provision for litigation

54,000

Total operating expenses

98,313

95,869

143,774

Operating loss

(4,840)

(8,070)

(72,429)

Other income (expense):

Interest expense

(86)

(80)

(918)

Interest income

670

494

123

Settlement and patent license income

14,900

Other, net

(264)

452

(98)

Total other income (expense)

15,220

866

(893)

Income (loss) before income taxes

10,380

(7,204)

(73,322)

Income tax expense

538

426

603

Net income (loss)

$ 9,842

$ (7,630)

$ (73,925)

Net income (loss) per share:

Basic (in dollars per share)

$ 0.09

$ (0.07)

$ (0.71)

Diluted (in dollars per share)

$ 0.08

$ (0.07)

$ (0.71)

Weighted average shares used in per share calculation:

Basic (shares)

112,114

108,814

104,350

Diluted (shares)

120,010

108,814

104,350

[1]	Cost of services excludes amortization related to intangibles, including existing technologies, customer relationships, and trade names and trademarks, which are included in depreciation and amortization

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 9,842	$ (7,630)	$ (73,925)
Other comprehensive gain (loss), net of tax:
Unrealized gain (loss) on investments	28	59	(84)
Foreign exchange translation (loss) gain	(1,733)	2,651	(142)
Other comprehensive (loss) gain, net of tax	(1,705)	2,710	(226)
Comprehensive income (loss)	$ 8,137	$ (4,920)	$ (74,151)

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

Summary of Significant Accounting Policies

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance, Shares at Dec. 31, 2015		102,299
Beginning balance at Dec. 31, 2015	$ 198,097,000	$ 102,000	$ 477,202,000	$ (10,812,000)	$ (268,395,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(73,925,000)				(73,925,000)
Change in unrealized loss on available-for-sale investments, net of taxes	(84,000)			(84,000)
Foreign currency translation adjustment, net of taxes	(142,000)			(142,000)
Exercise of common stock options, Shares		850
Exercise of common stock options	1,243,000	$ 0	1,243,000
Vesting of restricted stock units, Shares		3,753
Vesting of restricted stock units	0	$ 4,000	(4,000)
Restricted stock units surrendered in lieu of withholding taxes, Shares		(1,167)
Restricted stock units surrendered in lieu of withholding taxes	(1,979,000)	$ 0	(1,979,000)
Issuance of common stock under employee stock purchase plan, Shares		1,324
Issuance of common stock under employee stock purchase plan	1,498,000	$ 1,000	1,497,000
Purchases of common stock	0
Share-based compensation	12,860,000		12,860,000
Ending balance, Shares at Dec. 31, 2016		107,059
Ending balance at Dec. 31, 2016	137,568,000	$ 107,000	490,819,000	(11,038,000)	(342,320,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(7,630,000)				(7,630,000)
Change in unrealized loss on available-for-sale investments, net of taxes	59,000			59,000
Foreign currency translation adjustment, net of taxes	2,651,000			2,651,000
Exercise of common stock options, Shares		384
Exercise of common stock options	1,074,000	$ 0	1,074,000
Vesting of restricted stock units, Shares		4,004
Vesting of restricted stock units	0	$ 4,000	(4,000)
Restricted stock units surrendered in lieu of withholding taxes, Shares		(1,310)
Restricted stock units surrendered in lieu of withholding taxes	(4,497,000)	$ (1,000)	(4,496,000)
Issuance of common stock under employee stock purchase plan, Shares		687
Issuance of common stock under employee stock purchase plan	1,574,000	$ 1,000	1,573,000
Purchases of common stock	0
Share-based compensation	$ 13,346,000		13,346,000
Ending balance, Shares at Dec. 31, 2017	110,824	110,824
Ending balance at Dec. 31, 2017	$ 144,145,000	$ 111,000	502,312,000	(8,328,000)	(349,950,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	1,496,000				1,496,000
Net income (loss)	9,842,000				9,842,000
Change in unrealized loss on available-for-sale investments, net of taxes	28,000			28,000
Foreign currency translation adjustment, net of taxes	(1,733,000)			(1,733,000)
Exercise of common stock options, Shares		1,479
Exercise of common stock options	4,022,000	$ 1,000	4,021,000
Vesting of restricted stock units, Shares		3,501
Vesting of restricted stock units	0	$ 3,000	(3,000)
Restricted stock units surrendered in lieu of withholding taxes, Shares		(1,154)
Restricted stock units surrendered in lieu of withholding taxes	(4,793,000)	$ (1,000)	(4,792,000)
Issuance of common stock under employee stock purchase plan, Shares		596
Issuance of common stock under employee stock purchase plan	2,151,000	$ 1,000	2,150,000
Purchase of common stock, Shares		(1,000)
Purchases of common stock	(3,800,000)	$ (1,000)	(3,799,000)
Share-based compensation	$ 13,793,000		13,793,000
Ending balance, Shares at Dec. 31, 2018	114,246	114,246
Ending balance at Dec. 31, 2018	$ 165,151,000	$ 114,000	$ 513,682,000	$ (10,033,000)	$ (338,612,000)

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income (loss)	$ 9,842	$ (7,630)	$ (73,925)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	18,590	20,514	20,484
Share-based compensation	15,830	12,744	13,459
Settlement and patent license income	(14,900)	0	0
Accrual of provision for litigation	0	0	(54,000)
Foreign currency remeasurement (gain) loss	(162)	798	585
Deferred income taxes	17	(325)	170
Gain on sale of property and equipment	(137)	(410)	(514)
Accounts receivable charges	902	949	137
Amortization of premium on marketable securities	115	283	67
Realized loss on sale of marketable securities	0	0	32
Changes in operating assets and liabilities:
Accounts receivable	5,438	(5,912)	(760)
Prepaid expenses and other current assets	(2,466)	(342)	4,648
Income taxes receivable	(31)	38	39
Other assets	(558)	270	580
Accounts payable and other current liabilities	(4,333)	4,019	(1,757)
Deferred revenue	1,089	(957)	(822)
Income taxes payable	(333)	249	(8)
Payments related to litigation, net	(9,060)	(18,000)	(9,000)
Other long term liabilities	(121)	(790)	(857)
Net cash provided by operating activities	19,722	5,498	6,558
Investing activities
Purchases of marketable securities	(20,631)	(14,930)	(45,629)
Sale and maturities of marketable securities	23,865	30,756	29,315
Purchases of property and equipment	(16,113)	(20,725)	(9,563)
Proceeds from sale of property and equipment	135	97	504
Net cash used in investing activities	(12,744)	(4,802)	(25,373)
Financing activities
Principal payments on capital lease obligations	0	0	(4,685)
Payment of employee tax withholdings related to restricted stock vesting	(4,793)	(4,496)	(1,982)
Cash paid for purchase of common stock	(3,800)	0	0
Proceeds from employee stock plans	6,173	2,648	2,743
Net cash used in financing activities	(2,420)	(1,848)	(3,924)
Effect of exchange rate changes on cash and cash equivalents	(87)	330	(207)
Net increase (decrease) in cash and cash equivalents	4,471	(822)	(22,946)
Cash and cash equivalents, beginning of year	20,912	21,734	44,680
Cash and cash equivalents, end of year	25,383	20,912	21,734
Supplement disclosure of cash flow information
Cash paid during the year for interest	87	44	720
Cash paid during the year for income taxes, net of refunds	892	486	542
Property and equipment acquired through capital leases	$ 0	$ 0	$ 2,659

Nature of Business	12 Months Ended
Nature of Business	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Limelight Networks Inc., a leading provider of digital content delivery, video, cloud security, and edge computing services, empowers customers to provide exceptional digital experiences. Limelight’s edge services platform includes a unique combination of global private infrastructure, intelligent software, and expert support services that enable current and future workflows. We were incorporated in Delaware in 2003, and have operated in the Phoenix metropolitan area since 2001 and elsewhere throughout the United States since 2003. We began international operations in 2004.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP). The consolidated financial statements include accounts of Limelight and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. In addition, certain other reclassifications have been made to prior period amounts to conform to the current period presentation.

Use of Estimates

The preparation of the consolidated financial statements and related disclosures in conformity with U.S. GAAP requires management to make judgments, assumptions, and estimates that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results and outcomes may differ from those estimates. The results of operations presented in this annual report on Form 10-K are not necessarily indicative of the results that may be expected for the year ending December 31, 2019, or for any future periods.

Foreign Currency Translation

We translate assets and liabilities of foreign subsidiaries, whose functional currency is their local currency, at exchange rates in effect at the balance sheet date. We translate revenue and expenses at the monthly average exchange rates. We include accumulated net translation adjustments in stockholders’ equity as a component of accumulated other comprehensive income (loss).

The functional currency of our international subsidiaries is the local currency. Due to changes in exchange rates between reporting periods and changes in certain account balances, the foreign currency translation adjustment will change from period to period. During the years ended December 31, 2018, 2017, and 2016, we recorded foreign currency translation gains (losses) of $(1,733), $2,651, and $(142), respectively, in our statements of comprehensive income (loss).

Our entities occasionally transact in currencies other than their functional currencies. Assets denominated in foreign currencies other than that of the functional currency of the entity are remeasured at period-end exchange rates. Foreign currency-based revenue and expense transactions are measured at transaction date exchange rates. During the years ended December 31, 2018, 2017, and 2016, we recorded a foreign currency re-measurement gain (loss) of approximately $(405), $41, and $(982), respectively, in other income (expense) in the consolidated statements of operations.

Recent Accounting Standards

Adopted Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2014-09 (Topic 606) "Revenue from Contracts with Customers." Topic 606 supersedes the revenue recognition requirements in Accounting Standards Codification (ASC) Topic 605 “Revenue Recognition” (Topic 605), and requires entities to recognize revenue when control of promised goods or services is transferred to customers at an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services.

On January 1, 2018, we adopted Topic 606 using the modified retrospective method applied to those contracts which were not completed as of January 1, 2018. Results for reporting periods beginning after January 1, 2018 are presented under Topic 606, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under Topic 605.

We recorded a net decrease to opening accumulated deficit of $1,496 as of January 1, 2018 due to the cumulative impact of adopting Topic 606, with the impact primarily related to the costs to obtain a customer contract ($1,129), specifically commissions and upfront incentive payments, and from the recognition of revenue from customers with contracts that contain minimum commitments (greater than monthly) billed ratably over the contract term ($367).

Costs associated with obtaining a customer contract were previously expensed in the period they were incurred. Under Topic 606, these payments have been capitalized on our consolidated balance sheets and amortized over the expected life of the customer. The impact to sales and marketing expense for the year ended December 31, 2018 was not material as a result of applying Topic 606. As of December 31, 2018, prepaid commissions were $1,467, with the short term portion of $870 included in prepaid expenses and other current assets, and the long term portion of $597 included in other assets.

For customers with contracts that contain minimum commitments (greater than monthly) billed ratably over the contract term, previously, we either accrued or deferred revenue based on actual usage. Under Topic 606, we are required to evaluate the impact of estimating variable consideration related to these types of contracts. We use the expected value method to estimate the total revenue of the contract, constrained by the probability that there would not be a significant revenue reversal in a future period, and recognize a pro-rata share of the total revenue of the contract each month. We continue to evaluate the expected revenue over the term of the contract and adjust revenue recognition as appropriate. The impact to revenues for the year ended December 31, 2018 was an increase of $665, as a result of applying Topic 606.

In August 2016, the FASB issued ASU No. 2016-15, which amends ASC 230, to clarify guidance on the classification of certain cash receipts and payments in the statement of cash flows. The FASB issued ASU 2016-15 with the intent of reducing diversity in practice with respect to eight types of cash flows. We have adopted this guidance effective January 1, 2018. The adoption of this new guidance did not have a material impact on our consolidated financial statements.

In May 2017, the FASB issued ASU 2017-09, which clarifies when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. ASU 2017-09 will reduce diversity in practice and result in fewer changes to the terms of an award being accounted for as modifications. Under ASU 2017-09, an entity will not apply modification accounting to a share-based payment award if the award's fair value, vesting conditions and classification as an equity or liability instrument are the same immediately before and after the change. ASU 2017-09 will be applied prospectively to awards modified on or after the adoption date. We have adopted this guidance effective January 1, 2018. The adoption of this new guidance did not have a material impact on our consolidated financial statements.

Recently Issued Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016-02, which establishes a right-of-use model that requires a lessee to record a right-of-use asset and a lease liability on the balance sheet for most leases. In July 2018, the FASB issued ASU No. 2018-11, which amends the guidance to add a method of adoption whereby the issuer may elect to recognize a cumulative-effect adjustment at the beginning of the period of adoption. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. ASU 2016-02 defines a lease as a contract, or part of a contract, that conveys the right to control the use of identified property, plant or equipment for a period of time in exchange for consideration. To determine whether a contract conveys the right to control the use of the identified asset for a period of time, the customer has to have both (1) the right to obtain substantially all of the economic benefits from the use of the identified asset and (2) the right to direct the use of the identified asset, a contract does not contain an identified asset if the supplier has a substantive right to substitute such asset ("the leasing criteria"). Upon review of our co-location and bandwidth arrangements, we have preliminarily determined that such arrangements did not meet the leasing criteria, and therefore, we will not include these commitments in our right-of-use asset and lease liability on our balance sheet. We have preliminarily determined that our real estate leases with terms in excess of one year and do not include an option to purchase the underlying asset, do meet the leasing criteria, and will be treated similar to current operating lease accounting.

We plan to adopt the standard effective January 1, 2019, applying the package of practical expedients to leases that commenced before the effective date whereby we will elect to not reassess the following: (i) whether any expired or existing contracts contain leases; (ii) the lease classification for any expired or existing leases; and (iii) initial direct costs for any existing leases. We expect to record lease right of use assets and related liabilities on our balance sheet of approximately $4 million related to our operating leases. We have no financing leases. We expect no change to our consolidated statements of operations or cash flows.

In January 2017, the FASB issued ASU 2017-04, which simplifies the accounting for goodwill impairment. The updated guidance eliminates Step 2 of the impairment test, which requires entities to calculate the implied fair value of goodwill to measure a goodwill impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value, determined in Step 1. This guidance will become effective for us in fiscal years beginning after December 15, 2019, including interim periods within that reporting period. We will adopt this guidance using a prospective approach.

In June 2018, the FASB issued ASU 2018-07, which simplifies several aspects of the accounting for nonemployee share-based payment transactions resulting from expanding the scope of Topic 718, Compensation-Stock Compensation, to include share-based payment transactions for acquiring goods and services from nonemployees. Some of the areas for simplification apply only to nonpublic entities. The amendments specify that Topic 718 applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. The amendments also clarify that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under Topic 606, Revenue from Contracts with Customers. The amendments in this updated guidance are effective for public business entities for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. We will adopt this guidance effective January 1, 2019. We do not expect the adoption of this guidance to have a material impact on our consolidated financial statements and related disclosures.

In August 2018, the FASB issued ASU 2018-13, which removes, modifies and adds to the disclosure requirements on fair value measurements in Topic 820. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. This guidance will become effective for us in fiscal years beginning after December 15, 2019, including interim periods within that reporting period. Early adoption is permitted upon issuance of this updated guidance. An entity is permitted to early adopt any removed or modified disclosures upon issuance of this updated guidance and delay adoption of the additional disclosures until their effective date. We do not plan to early adopt this ASU, and we are currently evaluating the impact of this guidance on our consolidated financial statements.

In August 2018, the FASB issued ASU 2018-15, to help entities evaluate the accounting for fees paid by a customer in a cloud computing arrangement (hosting arrangement) by providing guidance for determining when the arrangement includes a software license. The amendments align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected by the amendments. This guidance will become effective for us in fiscal years beginning after December 15, 2019. Early adoption is permitted, including adoption in any interim period. We do not plan to early adopt this ASU, and are currently evaluating the impact that this guidance will have upon our financial position and results of operations, if any.

Revenue Recognition

Revenues are recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services.

Our customers generally execute contracts with terms of one year or longer, which are referred to as recurring revenue contracts or long-term contracts. These contracts generally allow the customer access to our network and commit the customer to a minimum monthly level of usage with additional charges applicable for actual usage above the monthly minimum commitment, or are entirely usage based. We define usage as customer data sent or received using our content delivery service, or content that is hosted or cached by us at the request or direction of our customers. For contracts that contain minimum monthly commitments, we recognize revenue equal to the greater of the minimum monthly committed amount or actual usage, if actual usage exceeds the monthly committed amount pursuant to Topic 606.

For contracts that contain minimum commitments over the contractual term (greater than monthly), we evaluate the amount of variable consideration by using either the expected value method or the most likely amount method. Generally, we we believe the expected value method represents the most appropriate estimate of the amount of variable consideration. We include estimates of variable consideration in revenue only when we have a high degree of confidence that revenue will not be reversed in a subsequent reporting period. These customers have entered into contracts with contract terms generally from one to four years. We recognized revenue of approximately $8,300 during the year ended December 31, 2018, related to these types of contracts with our customers.

As of December 31, 2018, we have approximately $6,500 of fixed consideration related to remaining unsatisfied performance obligations. We expect to recognize approximately 80% of the remaining unsatisfied performance obligations in 2019, 20% in 2020 with an immaterial amount thereafter.

We may charge the customer an installation fee when services are first activated. We do not charge installation fees for contract renewals. Installation fees are not distinct within the context of the overall contractual commitment with the customer to perform our content delivery service and are therefore recognized initially as deferred revenue and recognized as revenue ratably over the estimated life of the customer.

We also derive revenue from services and events sold as discrete, non-recurring events or based solely on usage. For these services, we recognize revenue when control of promised goods or services is transferred to customers at an amount that reflects the consideration to which we expect to be entitled to in exchange for those goods or services.

At the inception of a customer contract for service, we make an assessment as to that customer’s ability to pay for the services provided. If we subsequently determine that collection from the customer is not probable, we record an allowance for doubtful accounts and bad debt expense or deferred revenue for that customer’s unpaid invoices and cease recognizing revenue for continued services provided until it is probable that revenue will not be reversed in a subsequent reporting period. Our standard payment terms vary by the type and location of our customer.

Arrangements with Multiple Performance Obligations

Certain of our revenue arrangements include multiple promises to our customers. Revenue arrangements with multiple promises are accounted for as separate performance obligations if each promise is distinct. Such arrangements may include a combination of some or all of the following: content delivery services, video content management services, performance services for website and web application acceleration and security, professional services, cloud storage, edge computing services, and sale of equipment.

Judgment may be required in determining whether products or services are considered distinct performance obligations that should be accounted for separately or as one combined performance obligation. Revenue is recognized over the period in which the performance obligations are satisfied, which is generally over the contract term. We have determined that generally most of our products and services do not constitute an individual service offering to our customers, as our promise to the customer is to provide a complete edge services platform, and therefore have concluded that it represents a single performance obligation. We have determined that professional services and hardware sales represent separate performance obligations from that of our edge services platform.

Consideration is allocated to the performance obligations using the relative standalone selling price method. Generally, arrangements with performance obligations are provided over the same contract period, and therefore, revenue is recognized over the same period.

We determine standalone selling price by evaluating the overall pricing objectives and market conditions. Consideration included our discounting practices, the size and volume of our transactions, the area where services are sold, price lists, historical sales and contract prices.

Deferred Revenue

Deferred revenue represents amounts billed to customers for which revenue has not been recognized. Deferred revenue primarily consists of the unearned portion of monthly billed service fees and prepayments made by customers for services to be rendered in future periods.

Cash and Cash Equivalents

We hold our cash and cash equivalents in checking, money market, and highly-liquid investments. We consider all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents are deposited in or managed by major financial institutions and at times exceed Federal Deposit Insurance Corporation insurance limits.

Investments in Marketable Securities

Management determines the appropriate classification of its marketable securities at the time of purchase and reevaluates such classification as of each balance sheet date. We have classified our investments, which are all debt securities, in marketable securities as available-for-sale and as current, as our marketable securities are available to fund current operations, and carry such investments at fair value. Available-for-sale investments are initially recorded at cost with changes in fair value recorded through comprehensive loss. Realized gains and losses and declines in value judged to be other than temporary are determined based on the specific identification method and are reported in the statements of operations. We periodically review our investments for other-than-temporary declines in fair value based on the specific identification method and would write down investments to their fair value if and when an other-than-temporary decline has occurred.

Accounts Receivable

Trade accounts receivable are recorded at the invoiced amounts and do not bear interest. We record reserves against our accounts receivable balance for service credits and for doubtful accounts. Estimates are used in determining both of these reserves. The allowance for doubtful accounts charges are included as a component of general and administrative expenses.

The allowance for doubtful accounts is based upon a calculation that uses our aging of accounts receivable and applies a reserve percentage to the specific age of the receivable to estimate the allowance for doubtful accounts. The reserve percentages are determined based on our historical write-off experience. These estimates could change significantly if our customers’ financial condition changes or if the economy in general deteriorates. In the event such conditions become known, we specifically identify balances for necessary reserves.

Our reserve for service credits relates to credits that are expected to be issued to customers during the ordinary course of business. These credits typically relate to customer disputes and billing adjustments and are estimated at the time the revenue is recognized and recorded as a reduction of revenues. Estimates for service credits are based on an analysis of credits issued in previous periods.

Property and Equipment

Property and equipment are carried at cost less accumulated depreciation or amortization. Depreciation and amortization are computed using the straight-line method over the assets’ estimated useful lives of the applicable asset.



Network equipment	3 years
Computer equipment and software	3 years
Furniture and fixtures	3-5 years
Other equipment	3-5 years

Leasehold improvements are amortized over the shorter of the asset’s estimated useful life or the respective lease term. Repairs and maintenance are charged to expense as incurred.

Goodwill and Other Intangible Assets

Goodwill represents costs in excess of fair values assigned to the underlying net assets of the acquired company. Goodwill is not amortized but instead is tested for impairment annually or more frequently if events or changes in circumstances indicate goodwill might be impaired. We have concluded that we have one reporting unit and assigned the entire balance of goodwill to this reporting unit. The estimated fair value of the reporting unit is determined using a market approach. Our market capitalization is adjusted for a control premium based on the estimated average and median control premiums of transactions involving companies comparable to us. As of our annual impairment testing date of October 31, 2018, management determined that goodwill was not impaired. Management determined that the estimated fair value of its reporting unit exceeded carrying value by approximately $443,083 or 271%, using our market capitalization plus an estimated control premium of 33% on October 31, 2018. We updated our analysis as of December 31, 2018, and there were no indicators of impairment at that time.

As of December 31, 2018, we have no other unamortized intangible assets. However, in prior years, our other intangible assets represented existing technologies and customer relationship intangibles. Other intangible assets are amortized over their respective estimated lives, ranging from less than one year to six years. In the event that facts and circumstances indicate intangibles or other long-lived assets may be impaired, we evaluate the recoverability and estimated useful lives of such assets. Other intangible assets are included in other assets in the accompanying consolidated balance sheets. Amortization of other intangible assets is included in depreciation and amortization in the accompanying consolidated statements of operations.

Contingencies

We record contingent liabilities resulting from asserted and unasserted claims when it is probable that a loss has been incurred and the amount of the loss is reasonably estimable. We disclose contingent liabilities when there is a reasonable possibility that the ultimate loss will exceed the recorded liability. Additionally, estimating the loss, or range of loss, associated with a contingency requires analysis of multiple factors, and changes in law or other developments may ultimately cause our judgments to change. Therefore, actual losses in any future period are inherently uncertain and may be materially different from our estimate.

Long-Lived Assets

We review our long-lived assets for impairment annually, or whenever events or circumstances indicate that the carrying amount of an asset may not be fully recoverable. We recognize an impairment loss if the sum of the expected long-term undiscounted cash flows that the long-lived asset is expected to generate is less than the carrying amount of the long-lived asset being evaluated. We treat any write-downs as permanent reductions in the carrying amounts of the assets. We concluded that the carrying amounts of our long-lived assets at December 31, 2018, and 2017, are fully realizable and have not recorded any impairment losses.

Deferred Rent and Lease Accounting

We lease office space in various locations. At the inception of each lease, we evaluate the lease terms to determine whether the lease will be accounted for as an operating or a capital lease. The term of the lease used for this evaluation includes renewal option periods only in instances where the exercise of the renewal option can be reasonably assured and failure to exercise the option would result in an economic penalty. We record tenant improvement allowances granted under the lease agreements as leasehold improvements within property and equipment and within deferred rent.

For leases that contain rent escalation provisions, we record the total rent payable during the lease term on a straight-line basis over the term of the lease (including any “rent free” period beginning upon possession of the premises), and record any difference between the actual rent paid and the straight-line rent expense recorded as increases or decreases in deferred rent.

Cost of Revenue

Cost of revenues consists primarily of fees paid to network providers for bandwidth and backbone, costs incurred for non-settlement free peering and connection to internet service provider networks and fees paid to data center operators for housing network equipment in third party network data centers, also known as co-location costs. Cost of revenues also includes leased warehouse space and utilities, depreciation of network equipment used to deliver our content delivery services, payroll and related costs, and share-based compensation for our network operations and professional services personnel.

We enter into contracts for bandwidth with third party network providers with terms typically ranging from several months to five years. These contracts generally commit us to pay minimum monthly fees plus additional fees for bandwidth usage above contracted minimums. A portion of the global computing platform traffic delivery is completed through direct connection to ISP networks, called peering.

Research and Development

Research and development costs consist primarily of payroll and related personnel costs for the design, development, deployment, testing, operation, and enhancement of our services, and network. Costs incurred in the development of our services are expensed as incurred.

Advertising Costs

Costs associated with advertising are expensed as incurred. Advertising expenses, which are comprised of internet, trade show, and publications advertising, were approximately $2,169, $2,001, and $1,411 for the years ended December 31, 2018, 2017, and 2016, respectively.

Income Taxes

We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

We record net deferred tax assets to the extent we believe these assets will more likely than not be realized. In making such determination, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies, and recent financial performance on a jurisdiction by jurisdiction basis. In the event we were to determine that we would be able to realize our deferred income tax assets in the future in excess of their net recorded amount, we would make an adjustment to the valuation allowance, which would reduce the provision for income taxes.

We recognize uncertain income tax positions in our financial statements when it is more-likely-than-not the position will be sustained upon examination.

On December 22, 2017, the Tax Cuts and Jobs Act (the Tax Act) significantly revised the U.S. corporate income tax law, by among other things, reducing the corporate income tax rate to 21% for tax years beginning in 2018, implementing a modified territorial system that includes a one-time transition tax on deemed repatriated earnings of foreign subsidiaries and creating new taxes on certain foreign sourced earnings.

Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents approximate fair value due to the nature and short maturity of those instruments. The respective fair values of marketable securities are determined based on quoted market prices or other readily available market information, which approximate fair values. The carrying amounts of accounts receivable, accounts payable, and accrued liabilities reported in the consolidated balance sheets approximate their respective fair values due to the immediate or short-term maturity of these financial instruments.

Share-Based Compensation

We measure all employee share-based compensation awards using the fair-value method. The grant date fair value was determined using the Black-Scholes-Merton pricing model. The Black-Scholes-Merton valuation calculation requires us to make key assumptions such as future stock price volatility, expected terms, risk-free rates, and dividend yield. Our expected volatility is derived from our own volatility rate as a publicly traded company over the expected term of the awards. The expected term is based on our historical experience. The risk-free interest factor is based on the United States Treasury yield curve in effect at the time of the grant for zero coupon United States Treasury notes with maturities of approximately equal to each grant’s expected term. We have never paid cash dividends and do not currently intend to pay cash dividends, and therefore, have assumed a 0% dividend yield. We develop an estimate of the number of share-based awards that will be forfeited due to employee turnover. We will continue to use judgment in evaluating the expected term, volatility, and forfeiture rate related to our own share-based awards on a prospective basis, and in incorporating these factors into the model.

We apply the straight-line attribution method to recognize compensation costs associated with awards that are not subject to graded vesting. For awards that are subject to graded vesting and performance based awards, we recognize compensation costs separately for each vesting tranche. We also estimate when and if performance-based awards will be earned. If an award is not considered probable of being earned, no amount of share-based compensation is recognized. If the award is deemed probable of being earned, related compensation expense is recorded over the estimated service period. To the extent our estimate of awards considered probable of being earned changes, the amount of share-based compensation recognized will also change.

Investments in Marketable Securities

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Investments in Marketable Securities

The following is a summary of marketable securities (designated as available-for-sale) at December 31, 2018:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Certificate of deposit	$	40	$	—	$	—	$	40
Corporate notes and bonds	25,115		—		32		25,083
Total marketable securities	$	25,155	$	—	$	32	$	25,123

At December 31, 2018, we evaluated our marketable securities and determined unrealized losses were due to fluctuations in interest rates. We do not believe any of the unrealized losses represented an other-than-temporary impairment based on our evaluation of available evidence as of December 31, 2018. Our intent is to hold these investments to such time as these assets are no longer impaired.

The amortized cost and estimated fair value of the marketable securities at December 31, 2018, by maturity, are shown below:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale securities
Due in one year or less	$	25,115	$	—	$	32	$	25,083
Due after one year and through five years	40		—		—		40
	$	25,155	$	—	$	32	$	25,123

The following is a summary of marketable securities (designated as available-for-sale) at December 31, 2017:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Certificate of deposit	$	40	$	—	$	—	$	40
Corporate notes and bonds	28,472		—		68		28,404
Total marketable securities	$	28,512	$	—	$	68	$	28,444

The amortized cost and estimated fair value of the marketable securities at December 31, 2017, by maturity, are shown below:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale securities
Due in one year or less	$	23,924	$	—	$	62	$	23,862
Due after one year and through five years	4,588		—		6		4,582
	$	28,512	$	—	$	68	$	28,444

Accounts Receivable

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Accounts Receivable

Accounts receivable include:



	December 31,
	2018			2017
Accounts receivable	$	27,040		$	33,519
Less: credit allowance	(250		)	(240		)
Less: allowance for doubtful accounts	(749		)	(898		)
Total accounts receivable, net	$	26,041		$	32,381

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2018

Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets include:



	December 31,
	2018		2017
Settlement and patent license receivable	$	5,960	$	—
Prepaid bandwidth and backbone	1,395		1,487
VAT receivable	2,022		1,454
Prepaid expenses and insurance	1,816		1,870
Vendor deposits and other	3,596		586
Total prepaid expenses and other current assets	$	14,789	$	5,397

Goodwill

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

We have recorded goodwill as a result of past business acquisitions. Goodwill is recorded when the purchase price paid for an acquisition exceeds the estimated fair value of the net identified tangible and intangible assets acquired. In each of our acquisitions, the objective of the acquisition was to expand our product offerings and customer base and to achieve synergies related to cross selling opportunities, all of which contributed to the recognition of goodwill.

The changes in the carrying amount of goodwill for the years ended December 31, 2018, and 2017, were as follows:



Balance, December 31, 2016	$	76,243
Foreign currency translation adjustment	811
Balance, December 31, 2017	77,054
Foreign currency translation adjustment	(647		)
Balance, December 31, 2018	$	76,407

Property and Equipment

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and equipment include:



	December 31,
	2018			2017
Network equipment	$	105,760		$	107,916
Computer equipment and software	8,711			9,801
Furniture and fixtures	703			2,432
Leasehold improvements	4,587			3,969
Other equipment	156			183
	119,917			124,301
Less: accumulated depreciation	(92,539		)	(95,310		)
Total property and equipment, net	$	27,378		$	28,991

Cost of revenue depreciation expense related to property and equipment was approximately $16,277, $18,138, and $18,032, respectively, for the years ended December 31, 2018, 2017, and 2016, respectively.

Operating expense depreciation and amortization expense related to property and equipment was approximately $2,313, $2,376, and $2,438, respectively, for the years ended December 31, 2018, 2017, and 2016, respectively.

Line of Credit	12 Months Ended
Line of Credit	Dec. 31, 2018
Debt Disclosure [Abstract]
Line of Credit	Line of Credit In February 2018, we entered into a Fourth Amendment (Fourth Amendment) to the Loan and Security Agreement (the Credit Agreement) with Silicon Valley Bank (SVB) originally entered into in November 2015. Under the Fourth Amendment, we increased the maximum principal commitment amount from $10,000 to $20,000. Our borrowing capacity is the lesser of the commitment amount or 80% of eligible accounts receivable. The Fourth Amendment extends the Credit Agreement one year. All outstanding borrowings owed under the Credit Agreement become due and payable no later than the final maturity date of November 2, 2020. As of December 31, 2018, we had no outstanding borrowings, and we had availability under the Credit Agreement of approximately $20,000. We had no outstanding borrowings at December 31, 2017, and had availability under the Credit Agreement of approximately $10,000. As of December 31, 2018, borrowings under the Credit Agreement bear interest at the current prime rate minus 0.25%. In the event of default, obligations shall bear interest at a rate per annum that is 3% above the then applicable rate. We incurred an amendment fee of $50 upon entering into the Fourth Amendment. The amendment fee and other commitment fees are included in interest expense. During the years ended December 31, 2018, 2017 and 2016, respectively, interest expense was $0, $0 and $205, respectively, and fees expense and related amortization was $86, $80 and $321, respectively. Any borrowings are secured by essentially all of our domestic personal property, with a negative pledge on intellectual property. SVB’s security interest in our foreign subsidiaries is limited to 65% of voting stock of each such foreign subsidiary. Under the Fourth Amendment, we are required to maintain a minimum liquidity of $10,000 at all times, measured quarterly, with a minimum of $5,000 of the $10,000 in cash at SVB. In addition, we are required to maintain an Adjusted Quick Ratio of at least 1.0 to 1.0. We are also subject to certain customary limitations on our ability to, among other things, incur debt, grant liens, make acquisitions and other investments, make certain restricted payments such as dividends, dispose of assets or undergo a change in control. As of December 31, 2018, we were in compliance with all covenants under the Credit Agreement.

Other Current Liabilities

12 Months Ended

Dec. 31, 2018

Other Liabilities, Current [Abstract]

Other Current Liabilities

Other current liabilities include:



	December 31,
	2018		2017
Accrued compensation and benefits	$	7,528	$	12,181
Accrued cost of revenue	2,361		3,170
Accrued legal fees	22		383
Deferred rent	145		434
Other accrued expenses	2,866		2,339
Total other current liabilities	$	12,922	$	18,507

Contingencies	12 Months Ended
Contingencies	Dec. 31, 2018
Loss Contingency, Information about Litigation Matters [Abstract]
Contingencies	Contingencies Legal Matters Akamai ‘703 Litigation In 2016, we entered into a settlement and license agreement with Akamai Technologies, Inc. (Akamai) with respect to U.S. Patent No. 6,108,703 (the ‘703 patent) and certain other related patents, which settled all asserted and unasserted claims with respect to the licensed patents. The terms of the agreement require us to pay $54,000 over twelve equal quarterly installments, which began on August 1, 2016. We took a charge in the quarter ended June 30, 2016 for the full, undiscounted amount of $54,000. As of December 31, 2018, there remained $9,000 due to Akamai under the terms of the settlement and license agreement. Other Akamai Litigation On April 9, 2018, we entered into a definitive settlement and patent license agreement with Akamai in a separate matter where the parties agreed to (i) license certain patents to the other party, (ii) a covenant not to sue for three years for certain patents related to the licensed patents, and (iii) settle all outstanding legal disputes between the parties. The terms of the agreement also require Akamai to pay to Limelight a total of $14,900, over five equal quarterly installments. As of December 31, 2018, there remained $5,960 due from Akamai. Legal and other expenses associated with litigation have been significant. We include these litigation expenses in general and administrative expenses as incurred, as reported in the consolidated statement of operations. Other Matters We are subject to various other legal proceedings and claims, either asserted or unasserted, arising in the ordinary course of business. While the outcome of these claims cannot be predicted with certainty, management does not believe the outcome of any of these matters will have a material adverse effect on our business, financial position, results of operations, or cash flows, and accordingly, no legal contingencies are accrued as of December 31, 2018. Litigation relating to the content delivery services industry is not uncommon, and we are, and from time to time have been, subject to such litigation. No assurances can be given with respect to the extent or outcome of any such litigation in the future. Taxes We are subject to indirect taxation in various states and foreign jurisdictions. Laws and regulations that apply to communications and commerce conducted over the internet are becoming more prevalent, both in the United States and internationally, and may impose additional burdens on us conducting business online or providing internet-related services. Increased regulation could negatively affect our business directly, as well as the businesses of our customers, which could reduce their demand for our services. For example, tax authorities in various states and abroad may impose taxes on the internet-related revenue we generate based on regulations currently being applied to similar but not directly comparable industries. There are many transactions and calculations where the ultimate tax determination is uncertain. In addition, domestic and international taxation laws are subject to change. In the future, we may come under audit, which could result in changes to our tax estimates. We believe we maintain adequate tax reserves, that are not material in amount, to offset potential liabilities that may arise upon audit. Although we believe our tax estimates and associated reserves are reasonable, the final determination of tax audits and any related litigation could be materially different than the amounts established for tax contingencies. To the extent these estimates ultimately prove to be inaccurate, the associated reserves would be adjusted, resulting in the recording of a benefit or expense in the period in which a change in estimate or a final determination is made.

Net Income (Loss) per Share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Net Income (Loss) per Share

We calculate basic and diluted net income (loss) per weighted average share. We use the weighted-average number of shares of common stock outstanding during the period for the computation of basic earnings per share. Diluted earnings per share include the dilutive effect of all potentially dilutive common stock, including awards granted under our equity incentive compensation plans in the weighted-average number of shares of common stock outstanding.

The following table sets forth the components used in the computation of basic and diluted net income (loss) per share for the periods indicated:



	Years Ended December 31,
	2018		2017			2016
Net income (loss)	$	9,842	$	(7,630	)	$	(73,925	)
Basic weighted average outstanding shares of common stock	112,114		108,814			104,350
Basic weighted average outstanding shares of common stock	112,114		108,814			104,350
Dilutive effect of stock options, restricted stock units, and other equity incentive plans	7,896		—			—
Diluted weighted average outstanding shares of common stock	120,010		108,814			104,350
Basic net income (loss) per share	$	0.09	$	(0.07	)	$	(0.71	)
Diluted net income (loss) per share	$	0.08	$	(0.07	)	$	(0.71	)

For the years ended December 31, 2018, 2017 and 2016, the following potentially dilutive common stock, including awards granted under our equity incentive compensation plans were excluded from the computation of diluted net income (loss) per share because including them would have been anti-dilutive.



	Years Ended December 31,
	2018	2017	2016
Employee stock purchase plan	—	80	114
Stock options	3,288	2,643	71
Restricted stock units	451	3,332	1,122
	3,739	6,055	1,307

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock On March 14, 2017, our board of directors authorized a $25,000 share repurchase program. Any shares repurchased under this program will be canceled and returned to authorized but unissued status. This share repurchase program replaces the $9,500 remaining from the previously announced $15,000 share repurchase program. During the year ended December 31, 2018, we purchased and canceled 1,000 shares for $3,800, including commissions and expenses. We did not purchase any shares during the years ended December 31, 2017 and 2016, respectively. All repurchased shares were canceled and returned to authorized but unissued status. Amended and Restated Equity Incentive Plan We established the 2007 Equity Incentive Plan, or the 2007 Plan, which allows for the grant of equity, including stock options and restricted stock unit awards. In June 2016, our stockholders approved the Amended and Restated Equity Incentive Plan, or the Restated 2007 Plan, which amended and restated the 2007 Plan. Approval of the Restated 2007 Plan replaced the terms and conditions of the 2007 Plan with the terms and conditions of the Restated 2007 Plan and extended the term of the plan to April 2026. There was no increase in the aggregate amount of shares available for issuance. The total number of shares authorized for issuance under the Restated 2007 Plan as of December 31, 2018 was approximately 8,336. Employee Stock Purchase Plan In June 2013, our stockholders approved our 2013 Employee Stock Purchase Plan (ESPP). The ESPP allows participants to purchase our common stock at a 15% discount of the lower of the beginning or end of the offering period using the closing price on that day. During the years ended December 31, 2018, 2017, and 2016, we issued 596, 687, and 1,324 shares, respectively, under the ESPP. Total cash proceeds from the purchase of shares under the ESPP were approximately $2,157, $1,574, and $1,498, respectively for the years ended December 31, 2018, 2017, and 2016. As of December 31, 2018, shares reserved for issuance to employees under this plan totaled 34 and we held employee contributions of approximately $293 (included in other current liabilities) for future purchases under the ESPP. Preferred Stock Our board of directors have authorized the issuance of up to 7,500 shares of preferred stock at December 31, 2018. The preferred stock may be issued in one or more series pursuant to a resolution or resolutions providing for such issuance duly adopted by the board of directors. As of December 31, 2018, the Board had not adopted any resolutions for the issuance of preferred stock.

Accumulated Other Comprehensive Loss

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Accumulated Other Comprehensive Loss

Changes in the components of accumulated other comprehensive loss, net of tax, for the year ended December 31, 2018, was as follows:



				Unrealized
				Gains (Losses) on
	Foreign			Available for
	Currency			Sale Securities			Total
Balance, December 31, 2017	$	(8,259	)	$	(69	)	$	(8,328	)
Other comprehensive gain (loss) before reclassifications	(1,733		)	28			(1,705		)
Amounts reclassified from accumulated other comprehensive loss	—			—			—
Net current period other comprehensive gain (loss)	(1,733		)	28			(1,705		)
Balance, December 31, 2018	$	(9,992	)	$	(41	)	$	(10,033	)

Share-Based Compensation

12 Months Ended

Dec. 31, 2018

Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]

Share-Based Compensation

Incentive Compensation Plans

We maintain Incentive Compensation Plans (the Plans) to attract, motivate, retain, and reward high quality executives and other employees, officers, directors, and consultants by enabling such persons to acquire or increase a proprietary interest in the Company. The Plans are intended to be qualified plans under the Internal Revenue Code.

The Plans allow us to award stock option grants and restricted stock units (RSUs) to employees, directors and consultants of the Company. During 2018, we granted awards to employees and directors. The exercise price of incentive stock options granted under the Plan may not be granted at less than 100% of the fair market value of our common stock on the date of the grant.

Data pertaining to stock option activity under the Plans are as follows:



	Number of Shares		Weighted Average Exercise Price
	(In thousands)
Balance at December 31, 2015	14,667		$	3.33
Granted	3,589		2.22
Exercised	(850	)	1.46
Cancelled/Forfeitures	(1,389	)	3.38
Balance at December 31, 2016	16,017		3.18
Granted	2,082		4.56
Exercised	(384	)	2.79
Cancelled/Forfeitures	(752	)	11.04
Balance at December 31, 2017	16,963		2.99
Granted	2,126		3.50
Exercised	(1,479	)	2.72
Cancelled/Forfeitures	(667	)	5.23
Balance at December 31, 2018	16,943		2.99

The following table summarizes the information about stock options outstanding and exercisable at December 31, 2018:



Options Outstanding					Options Exercisable
Exercise Price	Number of Options Outstanding	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price		Number of Options Exercisable	Weighted Average Exercise Price
	(In thousands)				(In thousands)
$ 0.00 — $ 1.50	—	—	$	—	—	$	—
$ 1.51 — $ 3.00	11,142	5.7	2.26		9,977	2.26
$ 3.01 — $ 4.50	3,379	7.6	3.59		1,268	3.77
$ 4.51 — $ 6.00	2,209	5.7	5.32		1,324	5.25
$ 6.01 — $ 7.50	28	1.8	6.24		28	6.24
$ 7.51 — $ 15.00	185	2.1	8.05		185	8.05
	16,943				12,782

The weighted-average grant-date fair value of options granted during the years ended December 31, 2018, 2017, and 2016 on a per-share basis was approximately $1.82, $2.38, and $1.22, respectively. The total intrinsic value of the options exercised during the years ended December 31, 2018, 2017, and 2016 was approximately $3,171, $594, and $411, respectively. The aggregate intrinsic value of options outstanding at December 31, 2018 is approximately $1,436. The weighted average remaining contractual term of options currently exercisable at December 31, 2018 was 5.0 years.

The fair value of options awarded were estimated on the grant date using the following weighted average assumptions:



	Years Ended December 31,
	2018		2017		2016
Expected volatility	51.05	%	53.94	%	58.30	%
Expected term, years	6.19		6.13		5.99
Risk-free interest	2.91	%	2.11	%	1.76	%
Expected dividends	—	%	—	%	—	%

Unrecognized share-based compensation related to stock options totaled $7,203 at December 31, 2018. We expect to amortize unvested stock compensation related to stock options over a weighted average period of approximately 2.3 years at December 31, 2018.

The following table summarizes the RSUs outstanding (in thousands):



	Years Ended December 31,
	2018	2017	2016
RSUs with service-based vesting conditions	4,248	5,809	6,673

Each RSU represents the right to receive one share of our common stock upon vesting. The fair value of these RSUs was calculated based upon our closing stock price on the date of grant.

Data pertaining to RSUs activity under the Plans is as follows:



	Number of Units		Weighted Average Fair Value
	(In thousands)
Balance at December 31, 2015	6,265		$	2.70
Granted	5,024		1.76
Vested	(3,753	)	2.49
Forfeitures	(863	)	2.29
Balance at December 31, 2016	6,673		2.16
Granted	3,435		3.05
Vested	(4,004	)	2.16
Forfeitures	(295	)	2.23
Balance at December 31, 2017	5,809		2.68
Granted	2,475		3.88
Vested	(3,501	)	2.49
Forfeitures	(535	)	3.39
Balance at December 31, 2018	4,248		3.45

The weighted-average grant-date fair value of RSUs granted during the years ended December 31, 2018, 2017, and 2016 was approximately $3.88, $3.05, and $1.76, respectively. The total intrinsic value of the units vested during the years ended December 31, 2018, 2017, and 2016 was approximately $14,659, $13,531, and $6,314, respectively. The aggregate intrinsic value of RSUs outstanding at December 31, 2018 is $9,939.

At December 31, 2018 there was approximately $12,061 of total unrecognized compensation costs related to RSUs. That cost is expected to be recognized over a weighted-average period of approximately 2.09 years as of December 31, 2018.

Total unrecognized aggregate share-based compensation expense totaled approximately $19,264 at December 31, 2018, which is expected to be recognized over a weighted average period of approximately 2.15 years.

The following table summarizes the components of share-based compensation expense included in our consolidated statement of operations:



	Years Ended December 31,
	2018		2017		2016
Share-based compensation expense by type:
Stock options	$	4,238	$	3,813	$	3,742
Restricted stock units	10,753		8,402		9,121
ESPP	839		529		596
Total share-based compensation expense	$	15,830	$	12,744	$	13,459
Share-based compensation expense included in the consolidated statements of operations:
Cost of services	$	1,815	$	1,450	$	1,493
General and administrative expense	8,458		6,502		7,070
Sales and marketing expense	2,837		2,470		2,792
Research and development expense	2,720		2,322		2,104
Total share-based compensation expense	$	15,830	$	12,744	$	13,459

On September 18, 2015, the compensation committee of our board of directors approved a stock for salary program and a stock for bonus program, wherein eligible participants elected to receive payment of his or her base salary and/or bonus in shares of our common stock beginning on January 1, 2016. The shares of common stock were issued under our 2007 Equity Incentive Plan. Eligible program participants include our Chief Executive Officer and his direct reports.

The stock for salary program permitted eligible participants to receive 0, 25, 50, 75, or 100% of his or her 2016 salary (including any increases that may occur during the year) in shares of our common stock. On the last trading day of each calendar month, each participant will received the number of shares of our common stock determined by dividing (i) 1/12th of his or her enrolled salary by (ii) the trailing 30-day closing average of our common stock, rounded up to the nearest whole share. Once an election is made, it runs for the full year 2016 and is irrevocable. Participation levels may not be changed after the close of the enrollment period. Once purchased, there is no vesting period for the shares. During 2016, our Chief Executive Officer and two of his direct reports participated in the program. Each of the three participants elected to receive 50% of their respective salary in stock. As a result of their participation in the program, we issued 335 shares of common stock and recorded $572 of stock based compensation expense.

In 2018, 50% of the annual corporate bonus will be awarded to eligible employees in the form of our common stock. This resulted in $2,037 of stock based compensation expense in 2018.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions In July 2006, an aggregate of 39,869,960 shares of Series B Preferred Stock was issued at a purchase price of $3.26 per share to certain accredited investors in a private placement transaction. As a result of this transaction, entities affiliated with Goldman, Sachs & Co., one of the lead underwriters of our initial public offering (IPO), became holders of more than 10% of our common stock. On June 14, 2007, upon the closing of our IPO, all outstanding shares of our Series B Preferred Stock automatically converted into shares of common stock on a 1-for-1 share basis. Between November 2017 and March 2018, investment partnerships affiliated with Goldman, Sachs & Co. sold 30,272,493 shares that they had acquired upon the conversion of their Series B Preferred Stock at the time of the Company's IPO in June 2007. As of December 31, 2018, 2017, and 2016 Goldman, Sachs & Co. owned approximately 1%, 14% and 28%, respectively, of our outstanding common stock. We had no material related party transactions during the years ended December 31, 2018, 2017, and 2016.

Leases and Purchase Commitments

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Leases and Purchase Commitments

Operating Leases

We are committed to various non-cancellable operating leases for office space and office equipment which expire through 2022. Certain leases contain provisions for renewal options and rent escalations upon expiration of the initial lease terms. Approximate future minimum lease payments over the remaining lease periods as of December 31, 2018 are as follows:



2019	$	2,266
2020	1,309
2021	730
2022	55
2023	—
Thereafter	—
Total minimum payments	$	4,360

Purchase Commitments

We have non-cancellable long-term commitments for bandwidth usage and co-location with various networks and internet service providers or ISPs.

The following summarizes minimum commitments as of December 31, 2018:



2019	$	22,078
2020	3,685
2021	904
2022	244
2023	—
Thereafter	—
Total minimum payments	$	26,911

Rent and operating expense relating to these operating lease agreements and bandwidth and co-location agreements was approximately $59,593, $56,785, and $59,415, respectively, for the years ended December 31, 2018, 2017, and 2016.

Concentrations	12 Months Ended
Concentrations	Dec. 31, 2018
Risks and Uncertainties [Abstract]
Concentrations	Concentrations During the years ended December 31, 2018 and 2017, Amazon represented approximately 30% and 17%, respectively, of our total revenue. During the years ended December 31, 2016, we had no customer who represented 10% or more of our total revenue. Revenue from customers located within the United States, our country of domicile, was approximately $113,102, $112,166, and $94,105, respectively, for the years ended December 31, 2018, 2017, and 2016. During the years ended December 31, 2018 and 2017, respectively, we had three countries Japan, the United Kingdom and the United States, which accounted for 10% or more of our total revenue. During the year ended December 31, 2016, we had two countries, Japan and the United States, which accounted for 10% or more of our total revenue.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

Our income (loss) before income taxes consists of the following:



	Years Ended December 31,
	2018		2017			2016
Income (loss) before income taxes:
United States	$	8,648	$	(8,963	)	$	(74,130	)
Foreign	1,732		1,759			808
	$	10,380	$	(7,204	)	$	(73,322	)

The components of the provision for income taxes are as follows:



	Years Ended December 31,
	2018		2017			2016
Current:
Federal	$	—	$	—		$	—
State	32		40			103
Foreign	489		711			330
Total current	521		751			433
Deferred:
Federal	8		(34		)	15
State	3		3			—
Foreign	6		(294		)	155
Total deferred	17		(325		)	170
Total provision	$	538	$	426		$	603

A reconciliation of the U.S. federal statutory rate to our effective income tax rate is shown in the table below:



	Years Ended December 31,
	2018					2017					2016
	Amount			Percent		Amount			Percent		Amount			Percent
U.S. federal statutory tax rate	$	2,180		21.0	%	$	(2,521	)	35.0	%	$	(25,663	)	35.0	%
Valuation allowance	(1,845		)	(17.8	)%	(30,938		)	429.5	%	23,184			(31.6	)%
Foreign income taxes	150			1.5	%	(179		)	2.5	%	338			(0.5	)%
State income taxes	51			0.5	%	90			(1.2	)%	100			(0.2	)%
Non-deductible expenses	85			0.8	%	149			(2.1	)%	323			(0.4	)%
Uncertain tax positions	—			—	%	(20		)	0.3	%	(136		)	0.2	%
Non-deductible officer compensation	688			6.6	%	638			(8.9	)%	—			—	%
Share-based compensation	(745		)	(7.2	)%	873			(12.1	)%	2,439			(3.3	)%
Federal rate change impact	—			—	%	32,415			(450.0	)%	—			—	%
Other	(26		)	(0.2	)%	(81		)	1.1	%	18			—	%
Provision for income taxes	$	538		5.2	%	$	426		(5.9	)%	$	603		(0.8	)%

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purpose. Significant components of our deferred tax assets and liabilities are as follows:



	December 31,
	2018			2017
Deferred tax assets:
Share-based compensation	$	6,552		$	6,047
Net operating loss and tax credit carry-forwards	46,569			43,543
Legal settlement	2,281			6,738
Deferred revenue	418			1,084
Accounts receivable reserves	188			224
Fixed assets	2,687			2,222
Other	177			311
Total deferred tax assets	58,872			60,169
Deferred tax liabilities:
Prepaid expenses	(306		)	(81		)
Other	(107		)	(8		)
Total deferred tax liabilities	(413		)	(89		)
Valuation allowance	(57,149		)	(58,718		)
Net deferred tax assets	$	1,310		$	1,362

The federal and state net operating loss (NOL) carryforwards relate to prior years’ NOLs, which may be used to reduce tax liabilities in future years. At December 31, 2018, we had $186,100 federal and $126,400 state NOL carryforwards. Our federal NOL will begin to expire in 2027 and the state NOL carryforwards will begin to expire in 2019. Pursuant to Sections 382 and 383 of the Internal Revenue Code, the utilization of NOLs and other tax attributes may be subject to substantial limitations if certain ownership changes occur during a three-year testing period (as defined by the Internal Revenue Code). We did not have any state tax credit carryforwards as of December 31, 2018.

We reduce the carrying amounts of deferred tax assets by a valuation allowance if, based on the evidence available, it is more-likely-than-not that such assets will not be realized. In making the assessment under the more-likely-than-not standard, appropriate consideration must be given to all positive and negative evidence related to the realization of the deferred tax assets. This assessment considers, among other matters, the nature, frequency and severity of current and cumulative losses, forecasts of future profitability, the duration of statutory carry-forward periods by jurisdiction, unitary versus stand-alone state tax filings, our experience with loss carryforwards not expiring unutilized, and all tax planning alternatives that may be available.

A valuation allowance has been recorded against our deferred tax assets, with the exception of deferred tax assets at certain foreign subsidiaries as management cannot conclude that it is more-likely-than-not that these assets will be realized. As of December 31, 2018, no valuation allowance was provided on $1,600 of deferred tax assets associated with certain NOLs because we would use them to offset our liabilities relating to our uncertain tax benefits.

Estimated liabilities for unrecognized tax benefits are included in “other liabilities” on the consolidated balance sheet. These contingent liabilities relate to various tax matters that result from uncertainties in the application of complex income tax regulations in the numerous jurisdictions in which we operate. As of December 31, 2018, unrecognized tax benefits were $1,800, of which approximately $203, if recognized, would favorably impact the effective tax rate and the remaining balance would be substantially offset by valuation allowances.

A summary of the activities associated with our reserve for unrecognized tax benefits, interest and penalties follow:



	Unrecognized Tax Benefits
Balance at January 1, 2017	$	1,830
Additions for tax positions related to current year	—
Additions for tax positions related to prior years	26
Settlements	—
Adjustment related to foreign currency translation	3
Reductions related to the lapse of applicable statute of limitations	(42		)
Reduction for tax positions of prior years	—
Balance at December 31, 2017	1,817
Additions for tax positions related to current year	—
Additions for tax positions related to prior years	20
Settlements	(34		)
Adjustment related to foreign currency translation	—
Reductions related to the lapse of applicable statute of limitations	(3		)
Reduction for tax positions of prior years	—
Balance at December 31, 2018	$	1,800

We recognize interest and penalties related to unrecognized tax benefits in our tax provision. As of December 31, 2018, we had an interest and penalties accrual related to unrecognized tax benefits of $7, which decreased during 2018 by $5. We anticipate our unrecognized tax benefits may increase or decrease within twelve months of the reporting date, as audits or reviews are initiated or settled and as a result of settled potential tax liabilities in certain foreign jurisdictions. It is not currently reasonably possible to estimate the range of change.

We file income tax returns in jurisdictions with varying statues of limitations. Tax years 2015 through 2017 remain subject to examination by federal tax authorities. Tax years 2014 through 2017 generally remain subject to examination by state tax authorities. As of December 31, 2018, we are not under any federal or state income tax examinations.

Also on December 22, 2017, The Securities and Exchange Commission staff issued Staff Accounting Bulletin (SAB) 118 to provide guidance for companies that are not able to complete their accounting for the income tax effects of the Tax Act in the period of enactment. SAB 118 provides for a measurement period of up to one year from the date of enactment. During the measurement period, companies need to reflect adjustments to any provisional amounts if it obtains, prepares or analyzes additional information about facts and circumstances that existed as of the enactment date that, if known, would have affected the income tax effects initially reported as provisional amounts.

At December 31, 2018 we have completed our analysis of the Tax Act.

Income tax expense for the year ending December 31, 2017 includes a $41 tax benefit related to the re-measurement of a deferred tax liability on a long-lived asset. The remaining impact from the re-measurement of our net U.S. deferred tax asset at the lower 21% rate was offset by the valuation allowance. During 2018, this amount was finalized and no additional adjustment was required to be made.

The one-time transition tax is based on our total post-1986 earnings and profits (E&P) that we previously deferred from U.S. income taxes. In 2017 we recorded a provisional amount for our one-time transition tax liability for all of our foreign subsidiaries. In 2018 the transition tax calculation was completed. The transition tax that we calculated resulted in an immaterial amount of additional federal taxable income. The additional taxable income from the transition tax was offset by NOLs and did not result in cash taxes payable.

No additional income taxes have been provided for any remaining undistributed foreign earnings not subject to the transition tax, or any additional outside basis differences inherent in these entities, as these amounts continue to be indefinitely reinvested in foreign operations. Determining the amount of unrecognized deferred tax liability related to any remaining undistributed earnings not subject to the transition tax and additional outside basis difference in these entities (i.e. basis difference in excess of that subject to the one-time transition tax) is not practicable.

The Tax Act contains several base broadening provisions that became effective on January 1, 2018 that did not have a material impact on future earnings due to our NOL and valuation allowance position. Also effective for 2018 is a new Global Intangible Low-Taxed Income inclusion (GILTI). The GILTI did not have a material impact on our 2018 earnings due to our NOL and valuation allowance position.

401(k) Plan	12 Months Ended
401(k) Plan	Dec. 31, 2018
Retirement Benefits, Description [Abstract]
401(k) Plan	401(k) Plan We manage the Limelight Networks 401(k) Plan covering effectively all of our employees. The plan is a 401(k) profit sharing plan in which participating employees are fully vested in any contributions they make. We will match employee deferrals as follows: a dollar-for-dollar match on eligible employee’s deferral that does not exceed 3% of compensation for the year and a 50% match on the next 2% of the employee deferrals. Our employees may elect to reduce their current compensation up to the statutory limit. We made matching contributions of approximately $1,423, $1,327, and $1,345 during the years ended December 31, 2018, 2017, and 2016, respectively.

Segment Reporting and Geographic Information

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Segment Reporting and Geographic Information

Our chief operating decision maker (whom is our Chief Executive Officer) reviews the financial information presented on a consolidated basis for purposes of allocating resources and evaluating our financial performance. We operate in one industry segment — content delivery and related services and we operate in three geographic areas — Americas, Europe, Middle East and Africa (EMEA) and Asia Pacific.

Revenue by geography is based on the location of the customer from which the revenue is earned. The following table sets forth revenue by geographic area:



	Years Ended December 31,
	2018				2017				2016
Americas	$	118,462	61	%	$	116,112	63	%	$	100,421	60	%
EMEA	38,015		19	%	37,212		20	%	31,326		18	%
Asia Pacific	39,193		20	%	31,036		17	%	36,487		22	%
Total revenue	$	195,670	100	%	$	184,360	100	%	$	168,234	100	%

The following table sets forth the individual countries and their respective revenue for those countries whose revenue exceeded 10% of our total revenue:



	Years Ended December 31,
	2018		2017		2016
Country / Region
United States / Americas	$	113,102	$	112,166	$	94,105
United Kingdom / EMEA	$	26,672	$	22,456	$	15,290
Japan / Asia Pacific	$	20,452	$	18,585	$	19,967

The following table sets forth long-lived assets by geographic area:



	Years Ended December 31,
	2018		2017		2016
Long-lived Assets
Americas	$	18,349	$	17,119	$	18,665
International	9,029		11,872		11,687
Total long-lived assets	$	27,378	$	28,991	$	30,352

Fair Value Measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

We evaluate our financial instruments within the three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include:

Level 1 - defined as observable inputs such as quoted prices in active markets;

Level 2 - defined as other than quoted prices in active markets that are either directly or indirectly observable; and

Level 3 - defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.

As of December 31, 2018, and 2017, we held certain assets and liabilities that were required to be measured at fair value on a recurring basis. The following is a summary of fair value measurements at December 31, 2018:



			Fair Value Measurements at Reporting Date Using
Description	Total		Quoted Prices In Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (2)	$	752	$	752	$	—	$	—
Certificate of deposit (1)	40		—		40		—
Corporate notes and bonds (1)	25,083		—		25,083		—
Total assets measured at fair value	$	25,875	$	752	$	25,123	$	—

___________


(1)	Classified in marketable securities


(2)	Classified in cash and cash equivalents

The following is a summary of fair value measurements at December 31, 2017:



			Fair Value Measurements at Reporting Date Using
Description	Total		Quoted Prices In Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (2)	$	6,789	$	6,789	$	—	$	—
Certificate of deposit (1)	40		—		40		—
Corporate notes and bonds (1)	28,404		—		28,404		—
Total assets measured at fair value	$	35,233	$	6,789	$	28,444	$	—

____________


(1)	Classified in marketable securities


(2)	Classified in cash and cash equivalents

The carrying amount of cash equivalents approximates fair value because their maturity is less than three months. The carrying amount of short-term and long-term marketable securities approximates fair value as the securities are marked to market as of each balance sheet date with any unrealized gains and losses reported in stockholders’ equity. The carrying amount of accounts receivable, accounts payable and accrued liabilities approximates fair value due to the short-term maturity of the amounts.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Quarterly Financial Results (unaudited)

Quarterly Financial Results (unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Data [Abstract]

The following tables sets forth certain unaudited quarterly results of operations for the years ended December 31, 2018 and 2017. Amounts may not foot due to rounding.

In the opinion of management, this information has been prepared on the same basis as the audited consolidated financial statements and all necessary adjustments, consisting only of normal recurring adjustments, have been included in the amounts below for a fair statement of the quarterly information when read in conjunction with the audited consolidated financial statements and related notes included elsewhere in this annual report on Form 10-K:



	For the Three Months Ended
	March 31, 2018		June 30, 2018 (a)		Sept. 30, 2018			Dec. 31, 2018
Revenue	$	52,114	$	50,249	$	49,315		$	43,992
Gross profit	$	26,680	$	24,847	$	24,035		$	17,910
Net income (loss)	$	149	$	15,159	$	(272	)	$	(5,193	)
Basic net income (loss) per share	$	—	$	0.14	$	—		$	(0.05	)
Diluted net income (loss) per share	$	—	$	0.13	$	—		$	(0.05	)
Basic weighted average common shares outstanding	110,761		111,356		112,760			113,578
Diluted weighted average common shares outstanding	118,909		120,033		112,760			113,578



	For the Three Months Ended
	March 31, 2017			June 30, 2017			Sept. 30, 2017			Dec. 31, 2017
Revenue	$	44,735		$	45,370		$	46,069		$	48,186
Gross profit	$	21,171		$	21,375		$	22,276		$	22,977
Net loss	$	(3,337	)	$	(1,625	)	$	(1,756	)	$	(912	)
Basic and diluted net loss per share	$	(0.03	)	$	(0.01	)	$	(0.02	)	$	(0.01	)
Basic and diluted weighted average common shares outstanding	107,363			108,422			109,342			110,128

(a) During the quarter ended June 30, 2018, we recorded $14,900 of settlement and patent license income related to the definitive settlement and patent license agreement entered into with Akamai.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2018

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS

(In thousands)



			Additions				Deductions
Description	Balance at Beginning of Period		Charged to Costs and Expenses		Charged Against Revenue		Write-Offs Net of Recoveries	Balance at End of Period
Year ended December 31, 2016:
Allowances deducted from asset accounts:
Reserves for accounts receivable	$	1,804	137		(234	)	864	$	843
Deferred tax asset valuation allowance	$	59,241	24,985		—		—	$	84,226
Year ended December 31, 2017:
Allowances deducted from asset accounts:
Reserves for accounts receivable	$	843	949		14		668	$	1,138
Deferred tax asset valuation allowance	$	84,226	(25,508	)	—		—	$	58,718
Year ended December 31, 2018:
Allowances deducted from asset accounts:
Reserves for accounts receivable	$	1,138	902		10		1,051	$	999
Deferred tax asset valuation allowance	$	58,718	(1,569	)	—		—	$	57,149

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Foreign Currency Translation

Recent Accounting Standards

Adopted Accounting Pronouncements

Recently Issued Accounting Pronouncements

Revenue Recognition

Arrangements with Multiple Performance Obligations

Deferred Revenue

Cash and Cash Equivalents

Investments in Marketable Securities

Accounts Receivable

Property and Equipment



Network equipment	3 years
Computer equipment and software	3 years
Furniture and fixtures	3-5 years
Other equipment	3-5 years

Leasehold improvements are amortized over the shorter of the asset’s estimated useful life or the respective lease term. Repairs and maintenance are charged to expense as incurred.

Goodwill and Other Intangible Assets

Contingencies

Long-Lived Assets

Deferred Rent and Lease Accounting

Cost of Revenue

Research and Development

Advertising Costs

Costs associated with advertising are expensed as incurred.

Income Taxes

We recognize uncertain income tax positions in our financial statements when it is more-likely-than-not the position will be sustained upon examination.

Fair Value of Financial Instruments

Share-Based Compensation

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Estimated useful lives of assets

Depreciation and amortization are computed using the straight-line method over the assets’ estimated useful lives of the applicable asset.



Network equipment	3 years
Computer equipment and software	3 years
Furniture and fixtures	3-5 years
Other equipment	3-5 years

Investments in Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of marketable securities

The following is a summary of marketable securities (designated as available-for-sale) at December 31, 2017:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Certificate of deposit	$	40	$	—	$	—	$	40
Corporate notes and bonds	28,472		—		68		28,404
Total marketable securities	$	28,512	$	—	$	68	$	28,444

The following is a summary of marketable securities (designated as available-for-sale) at December 31, 2018:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Certificate of deposit	$	40	$	—	$	—	$	40
Corporate notes and bonds	25,115		—		32		25,083
Total marketable securities	$	25,155	$	—	$	32	$	25,123

Amortized cost and estimated fair value of marketable securities (designated as available-for-sale) by maturity

The amortized cost and estimated fair value of the marketable securities at December 31, 2017, by maturity, are shown below:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale securities
Due in one year or less	$	23,924	$	—	$	62	$	23,862
Due after one year and through five years	4,588		—		6		4,582
	$	28,512	$	—	$	68	$	28,444

The amortized cost and estimated fair value of the marketable securities at December 31, 2018, by maturity, are shown below:



	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available-for-sale securities
Due in one year or less	$	25,115	$	—	$	32	$	25,083
Due after one year and through five years	40		—		—		40
	$	25,155	$	—	$	32	$	25,123

Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Summary of accounts receivable, net

Accounts receivable include:



	December 31,
	2018			2017
Accounts receivable	$	27,040		$	33,519
Less: credit allowance	(250		)	(240		)
Less: allowance for doubtful accounts	(749		)	(898		)
Total accounts receivable, net	$	26,041		$	32,381

Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2018

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Schedule of prepaid expenses and other current assets

Prepaid expenses and other current assets include:



	December 31,
	2018		2017
Settlement and patent license receivable	$	5,960	$	—
Prepaid bandwidth and backbone	1,395		1,487
VAT receivable	2,022		1,454
Prepaid expenses and insurance	1,816		1,870
Vendor deposits and other	3,596		586
Total prepaid expenses and other current assets	$	14,789	$	5,397

Goodwill (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of changes in the carrying amount of goodwill

The changes in the carrying amount of goodwill for the years ended December 31, 2018, and 2017, were as follows:



Balance, December 31, 2016	$	76,243
Foreign currency translation adjustment	811
Balance, December 31, 2017	77,054
Foreign currency translation adjustment	(647		)
Balance, December 31, 2018	$	76,407

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property and equipment, net

Property and equipment include:



	December 31,
	2018			2017
Network equipment	$	105,760		$	107,916
Computer equipment and software	8,711			9,801
Furniture and fixtures	703			2,432
Leasehold improvements	4,587			3,969
Other equipment	156			183
	119,917			124,301
Less: accumulated depreciation	(92,539		)	(95,310		)
Total property and equipment, net	$	27,378		$	28,991

Other Current Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Other Liabilities, Current [Abstract]

Other current liabilities

Other current liabilities include:



	December 31,
	2018		2017
Accrued compensation and benefits	$	7,528	$	12,181
Accrued cost of revenue	2,361		3,170
Accrued legal fees	22		383
Deferred rent	145		434
Other accrued expenses	2,866		2,339
Total other current liabilities	$	12,922	$	18,507

Net Income (Loss) per Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Computation of basic and diluted net income (loss) per share

The following table sets forth the components used in the computation of basic and diluted net income (loss) per share for the periods indicated:



	Years Ended December 31,
	2018		2017			2016
Net income (loss)	$	9,842	$	(7,630	)	$	(73,925	)
Basic weighted average outstanding shares of common stock	112,114		108,814			104,350
Basic weighted average outstanding shares of common stock	112,114		108,814			104,350
Dilutive effect of stock options, restricted stock units, and other equity incentive plans	7,896		—			—
Diluted weighted average outstanding shares of common stock	120,010		108,814			104,350
Basic net income (loss) per share	$	0.09	$	(0.07	)	$	(0.71	)
Diluted net income (loss) per share	$	0.08	$	(0.07	)	$	(0.71	)

Schedule of antidilutive securities excluded from computation of earnings per share



	Years Ended December 31,
	2018	2017	2016
Employee stock purchase plan	—	80	114
Stock options	3,288	2,643	71
Restricted stock units	451	3,332	1,122
	3,739	6,055	1,307

Accumulated Other Comprehensive Loss (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Schedule of accumulated other comprehensive loss

Changes in the components of accumulated other comprehensive loss, net of tax, for the year ended December 31, 2018, was as follows:



				Unrealized
				Gains (Losses) on
	Foreign			Available for
	Currency			Sale Securities			Total
Balance, December 31, 2017	$	(8,259	)	$	(69	)	$	(8,328	)
Other comprehensive gain (loss) before reclassifications	(1,733		)	28			(1,705		)
Amounts reclassified from accumulated other comprehensive loss	—			—			—
Net current period other comprehensive gain (loss)	(1,733		)	28			(1,705		)
Balance, December 31, 2018	$	(9,992	)	$	(41	)	$	(10,033	)

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]

Stock option activity

Data pertaining to stock option activity under the Plans are as follows:



	Number of Shares		Weighted Average Exercise Price
	(In thousands)
Balance at December 31, 2015	14,667		$	3.33
Granted	3,589		2.22
Exercised	(850	)	1.46
Cancelled/Forfeitures	(1,389	)	3.38
Balance at December 31, 2016	16,017		3.18
Granted	2,082		4.56
Exercised	(384	)	2.79
Cancelled/Forfeitures	(752	)	11.04
Balance at December 31, 2017	16,963		2.99
Granted	2,126		3.50
Exercised	(1,479	)	2.72
Cancelled/Forfeitures	(667	)	5.23
Balance at December 31, 2018	16,943		2.99

Outstanding stock options

The following table summarizes the information about stock options outstanding and exercisable at December 31, 2018:



Options Outstanding					Options Exercisable
Exercise Price	Number of Options Outstanding	Weighted Average Remaining Contractual Life (Years)	Weighted Average Exercise Price		Number of Options Exercisable	Weighted Average Exercise Price
	(In thousands)				(In thousands)
$ 0.00 — $ 1.50	—	—	$	—	—	$	—
$ 1.51 — $ 3.00	11,142	5.7	2.26		9,977	2.26
$ 3.01 — $ 4.50	3,379	7.6	3.59		1,268	3.77
$ 4.51 — $ 6.00	2,209	5.7	5.32		1,324	5.25
$ 6.01 — $ 7.50	28	1.8	6.24		28	6.24
$ 7.51 — $ 15.00	185	2.1	8.05		185	8.05
	16,943				12,782

Grant date fair value of option

The fair value of options awarded were estimated on the grant date using the following weighted average assumptions:



	Years Ended December 31,
	2018		2017		2016
Expected volatility	51.05	%	53.94	%	58.30	%
Expected term, years	6.19		6.13		5.99
Risk-free interest	2.91	%	2.11	%	1.76	%
Expected dividends	—	%	—	%	—	%

Different types of restricted stock units (RSUs) outstanding

The following table summarizes the RSUs outstanding (in thousands):



	Years Ended December 31,
	2018	2017	2016
RSUs with service-based vesting conditions	4,248	5,809	6,673

Restricted stock units activity

Data pertaining to RSUs activity under the Plans is as follows:



	Number of Units		Weighted Average Fair Value
	(In thousands)
Balance at December 31, 2015	6,265		$	2.70
Granted	5,024		1.76
Vested	(3,753	)	2.49
Forfeitures	(863	)	2.29
Balance at December 31, 2016	6,673		2.16
Granted	3,435		3.05
Vested	(4,004	)	2.16
Forfeitures	(295	)	2.23
Balance at December 31, 2017	5,809		2.68
Granted	2,475		3.88
Vested	(3,501	)	2.49
Forfeitures	(535	)	3.39
Balance at December 31, 2018	4,248		3.45

Components of share-based compensation expense

The following table summarizes the components of share-based compensation expense included in our consolidated statement of operations:



	Years Ended December 31,
	2018		2017		2016
Share-based compensation expense by type:
Stock options	$	4,238	$	3,813	$	3,742
Restricted stock units	10,753		8,402		9,121
ESPP	839		529		596
Total share-based compensation expense	$	15,830	$	12,744	$	13,459
Share-based compensation expense included in the consolidated statements of operations:
Cost of services	$	1,815	$	1,450	$	1,493
General and administrative expense	8,458		6,502		7,070
Sales and marketing expense	2,837		2,470		2,792
Research and development expense	2,720		2,322		2,104
Total share-based compensation expense	$	15,830	$	12,744	$	13,459

Leases and Purchase Commitments (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Future minimum lease payments over remaining lease periods

Approximate future minimum lease payments over the remaining lease periods as of December 31, 2018 are as follows:



2019	$	2,266
2020	1,309
2021	730
2022	55
2023	—
Thereafter	—
Total minimum payments	$	4,360

Minimum purchase commitments

The following summarizes minimum commitments as of December 31, 2018:



2019	$	22,078
2020	3,685
2021	904
2022	244
2023	—
Thereafter	—
Total minimum payments	$	26,911

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Loss before income taxes

Our income (loss) before income taxes consists of the following:



	Years Ended December 31,
	2018		2017			2016
Income (loss) before income taxes:
United States	$	8,648	$	(8,963	)	$	(74,130	)
Foreign	1,732		1,759			808
	$	10,380	$	(7,204	)	$	(73,322	)

Components of provision (benefit) for income taxes

The components of the provision for income taxes are as follows:



	Years Ended December 31,
	2018		2017			2016
Current:
Federal	$	—	$	—		$	—
State	32		40			103
Foreign	489		711			330
Total current	521		751			433
Deferred:
Federal	8		(34		)	15
State	3		3			—
Foreign	6		(294		)	155
Total deferred	17		(325		)	170
Total provision	$	538	$	426		$	603

Reconciliation of the U.S. federal statutory rate to the Company's effective income tax rate

A reconciliation of the U.S. federal statutory rate to our effective income tax rate is shown in the table below:



	Years Ended December 31,
	2018					2017					2016
	Amount			Percent		Amount			Percent		Amount			Percent
U.S. federal statutory tax rate	$	2,180		21.0	%	$	(2,521	)	35.0	%	$	(25,663	)	35.0	%
Valuation allowance	(1,845		)	(17.8	)%	(30,938		)	429.5	%	23,184			(31.6	)%
Foreign income taxes	150			1.5	%	(179		)	2.5	%	338			(0.5	)%
State income taxes	51			0.5	%	90			(1.2	)%	100			(0.2	)%
Non-deductible expenses	85			0.8	%	149			(2.1	)%	323			(0.4	)%
Uncertain tax positions	—			—	%	(20		)	0.3	%	(136		)	0.2	%
Non-deductible officer compensation	688			6.6	%	638			(8.9	)%	—			—	%
Share-based compensation	(745		)	(7.2	)%	873			(12.1	)%	2,439			(3.3	)%
Federal rate change impact	—			—	%	32,415			(450.0	)%	—			—	%
Other	(26		)	(0.2	)%	(81		)	1.1	%	18			—	%
Provision for income taxes	$	538		5.2	%	$	426		(5.9	)%	$	603		(0.8	)%

Components of Company's deferred tax assets and liabilities



	December 31,
	2018			2017
Deferred tax assets:
Share-based compensation	$	6,552		$	6,047
Net operating loss and tax credit carry-forwards	46,569			43,543
Legal settlement	2,281			6,738
Deferred revenue	418			1,084
Accounts receivable reserves	188			224
Fixed assets	2,687			2,222
Other	177			311
Total deferred tax assets	58,872			60,169
Deferred tax liabilities:
Prepaid expenses	(306		)	(81		)
Other	(107		)	(8		)
Total deferred tax liabilities	(413		)	(89		)
Valuation allowance	(57,149		)	(58,718		)
Net deferred tax assets	$	1,310		$	1,362

Summary of activities associated with Company's reserve for unrecognized tax benefits interest and penalties

A summary of the activities associated with our reserve for unrecognized tax benefits, interest and penalties follow:



	Unrecognized Tax Benefits
Balance at January 1, 2017	$	1,830
Additions for tax positions related to current year	—
Additions for tax positions related to prior years	26
Settlements	—
Adjustment related to foreign currency translation	3
Reductions related to the lapse of applicable statute of limitations	(42		)
Reduction for tax positions of prior years	—
Balance at December 31, 2017	1,817
Additions for tax positions related to current year	—
Additions for tax positions related to prior years	20
Settlements	(34		)
Adjustment related to foreign currency translation	—
Reductions related to the lapse of applicable statute of limitations	(3		)
Reduction for tax positions of prior years	—
Balance at December 31, 2018	$	1,800

Segment Reporting and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Revenue by geography

Revenue by geography is based on the location of the customer from which the revenue is earned. The following table sets forth revenue by geographic area:



	Years Ended December 31,
	2018				2017				2016
Americas	$	118,462	61	%	$	116,112	63	%	$	100,421	60	%
EMEA	38,015		19	%	37,212		20	%	31,326		18	%
Asia Pacific	39,193		20	%	31,036		17	%	36,487		22	%
Total revenue	$	195,670	100	%	$	184,360	100	%	$	168,234	100	%

The following table sets forth the individual countries and their respective revenue for those countries whose revenue exceeded 10% of our total revenue:



	Years Ended December 31,
	2018		2017		2016
Country / Region
United States / Americas	$	113,102	$	112,166	$	94,105
United Kingdom / EMEA	$	26,672	$	22,456	$	15,290
Japan / Asia Pacific	$	20,452	$	18,585	$	19,967

Long-lived assets by geography

The following table sets forth long-lived assets by geographic area:



	Years Ended December 31,
	2018		2017		2016
Long-lived Assets
Americas	$	18,349	$	17,119	$	18,665
International	9,029		11,872		11,687
Total long-lived assets	$	27,378	$	28,991	$	30,352

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Summary of money market funds, marketable securities, other investment-related assets and current liabilities

The following is a summary of fair value measurements at December 31, 2018:



			Fair Value Measurements at Reporting Date Using
Description	Total		Quoted Prices In Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (2)	$	752	$	752	$	—	$	—
Certificate of deposit (1)	40		—		40		—
Corporate notes and bonds (1)	25,083		—		25,083		—
Total assets measured at fair value	$	25,875	$	752	$	25,123	$	—

___________


(1)	Classified in marketable securities


(2)	Classified in cash and cash equivalents

The following is a summary of fair value measurements at December 31, 2017:



			Fair Value Measurements at Reporting Date Using
Description	Total		Quoted Prices In Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Money market funds (2)	$	6,789	$	6,789	$	—	$	—
Certificate of deposit (1)	40		—		40		—
Corporate notes and bonds (1)	28,404		—		28,404		—
Total assets measured at fair value	$	35,233	$	6,789	$	28,444	$	—

____________


(1)	Classified in marketable securities


(2)	Classified in cash and cash equivalents

Quarterly Financial Results (unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Data [Abstract]

Quarterly results of operations (unaudited)

Quarterly Financial Results (unaudited)

The following tables sets forth certain unaudited quarterly results of operations for the years ended December 31, 2018 and 2017. Amounts may not foot due to rounding.



	For the Three Months Ended
	March 31, 2018		June 30, 2018 (a)		Sept. 30, 2018			Dec. 31, 2018
Revenue	$	52,114	$	50,249	$	49,315		$	43,992
Gross profit	$	26,680	$	24,847	$	24,035		$	17,910
Net income (loss)	$	149	$	15,159	$	(272	)	$	(5,193	)
Basic net income (loss) per share	$	—	$	0.14	$	—		$	(0.05	)
Diluted net income (loss) per share	$	—	$	0.13	$	—		$	(0.05	)
Basic weighted average common shares outstanding	110,761		111,356		112,760			113,578
Diluted weighted average common shares outstanding	118,909		120,033		112,760			113,578



	For the Three Months Ended
	March 31, 2017			June 30, 2017			Sept. 30, 2017			Dec. 31, 2017
Revenue	$	44,735		$	45,370		$	46,069		$	48,186
Gross profit	$	21,171		$	21,375		$	22,276		$	22,977
Net loss	$	(3,337	)	$	(1,625	)	$	(1,756	)	$	(912	)
Basic and diluted net loss per share	$	(0.03	)	$	(0.01	)	$	(0.02	)	$	(0.01	)
Basic and diluted weighted average common shares outstanding	107,363			108,422			109,342			110,128

(a) During the quarter ended June 30, 2018, we recorded $14,900 of settlement and patent license income related to the definitive settlement and patent license agreement entered into with Akamai.

Summary of Significant Accounting Policies - Additional Information (Details)

3 Months Ended

12 Months Ended

Jan. 01, 2018

USD ($)

Oct. 31, 2016

USD ($)

Dec. 31, 2018

USD ($)

Sep. 30, 2018

USD ($)

Jun. 30, 2018

USD ($)

^[1]

Mar. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Sep. 30, 2017

USD ($)

Jun. 30, 2017

USD ($)

Mar. 31, 2017

USD ($)

Dec. 31, 2018

USD ($)

reporting_unit

Dec. 31, 2017

USD ($)

Dec. 31, 2016

USD ($)

Jan. 01, 2019

USD ($)

Foreign Currency Translation:

Foreign exchange translation (loss) gain

$ (1,733,000)

$ 2,651,000

$ (142,000)

Foreign currency re-measurement gain (loss)

(405,000)

41,000

(982,000)

Decrease in accumulated deficit

$ (338,612,000)

$ (349,950,000)

(338,612,000)

(349,950,000)

Capitalized contract cost

1,467,000

Capitalized contract cost, current

43,992,000

$ 49,315,000

$ 50,249,000

$ 52,114,000

$ 48,186,000

$ 46,069,000

$ 45,370,000

$ 44,735,000

195,670,000

184,360,000

168,234,000

870,000

Capitalized contract cost, noncurrent

$ 597,000

Goodwill and Other Intangible Assets:

Number of reporting units | reporting_unit

Estimated fair value in excess of carrying value of goodwill

$ 443,083,000

Percentage of estimated fair value of goodwill exceeding carrying value

271.00%

Control premium used to determine fair value of goodwill

33.00%

Long-Lived Assets:

Impairment of long-lived assets

$ 0

Advertising Costs:

Advertising expenses

2,169,000

$ 2,001,000

$ 1,411,000

Income Taxes:

$ 41,000

Share-based Compensation:

Expected dividend rate

0.00%

Minimum

Goodwill and Other Intangible Assets:

Estimated lives of other intangible assets (less than one year)

1 year

Maximum

Goodwill and Other Intangible Assets:

Estimated lives of other intangible assets (less than one year)

6 years

Cost of Revenue:

Term of contract with third party

5 years

Subsequent Event | ASU 2018-11

Difference between Revenue Guidance in Effect before and after Topic 606 | ASU 2014-09

Lease liability

$ 4,000,000

Lease asset

$ 4,000,000

Decrease in accumulated deficit

$ 1,496,000

Capitalized contract cost

1,129,000

Transferred over Time

Transferred over Time | Difference between Revenue Guidance in Effect before and after Topic 606 | ASU 2014-09

$ 665,000

Computation of basic and diluted net income (loss) per share

$ 367,000

[1]	During the quarter ended June 30, 2018, we recorded $14,900 of settlement and patent license income related to the definitive settlement and patent license agreement entered into with Akamai.

Summary of Significant Accounting Policies - Revenue Performance Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018
Accounting Policies [Abstract]
Timing of performance obligation	These customers have entered into contracts with contract terms generally from one to four years.
Unsatisfied performance obligations	$ 6,500
Revenue recognized upon completion of performance obligation	$ 8,300
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Percent of remaining performance obligations	80.00%
Period of fulfillment of remaining performance obligations		3 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Percent of remaining performance obligations	20.00%
Period of fulfillment of remaining performance obligations		1 year

Summary of Significant Accounting Policies - Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Network equipment
Estimated useful lives of assets
Estimated useful lives of assets	3 years
Computer equipment and software
Estimated useful lives of assets
Estimated useful lives of assets	3 years
Furniture and fixtures \| Minimum
Estimated useful lives of assets
Estimated useful lives of assets	3 years
Furniture and fixtures \| Maximum
Estimated useful lives of assets
Estimated useful lives of assets	5 years
Other equipment \| Minimum
Estimated useful lives of assets
Estimated useful lives of assets	3 years
Other equipment \| Maximum
Estimated useful lives of assets
Estimated useful lives of assets	5 years

Investments in Marketable Securities - Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Summary of marketable securities (designated as available-for-sale)
Amortized Cost	$ 25,155	$ 28,512
Gross Unrealized Gains	0	0
Gross Unrealized Losses	32	68
Estimated Fair Value	25,123	28,444
Certificate of deposit
Summary of marketable securities (designated as available-for-sale)
Amortized Cost	40	40
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	40	40
Corporate notes and bonds
Summary of marketable securities (designated as available-for-sale)
Amortized Cost	25,115	28,472
Gross Unrealized Gains	0	0
Gross Unrealized Losses	32	68
Estimated Fair Value	$ 25,083	$ 28,404

Investments in Marketable Securities - Amortized cost and Estimated Fair Value of Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Amortized Cost	$ 25,115	$ 23,924
Due after one year and through five years, Amortized Cost	40	4,588
Amortized Cost	25,155	28,512
Due in one year or less, Gross Unrealized Gains	0	0
Due after one year and through five years, Gross Unrealized Gains	0	0
Gross Unrealized Gains	0	0
Due in one year or less, Gross Unrealized Losses	32	62
Due after one year and through five years, Gross Unrealized Losses	0	6
Gross Unrealized Losses	32	68
Due in one year or less, Estimated Fair Value	25,083	23,862
Due after one year and through five years, Estimated Fair Value	40	4,582
Estimated Fair Value	$ 25,123	$ 28,444

Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Summary of Accounts receivable, net
Accounts receivable	$ 27,040	$ 33,519
Less: credit allowance	(250)	(240)
Less: allowance for doubtful accounts	(749)	(898)
Total accounts receivable, net	$ 26,041	$ 32,381

Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Settlement and patent license receivable	$ 5,960	$ 0
Prepaid bandwidth and backbone	1,395	1,487
VAT receivable	2,022	1,454
Prepaid expenses and insurance	1,816	1,870
Vendor deposits and other	3,596	586
Total prepaid expenses and other current assets	$ 14,789	$ 5,397

Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
Goodwill (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of changes in the carrying amount of goodwill
Beginning Balance	$ 77,054	$ 76,243
Foreign currency translation adjustment	(647)	811
Ending Balance	$ 76,407	$ 77,054

Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property and equipment, net
Property and equipment, gross	$ 119,917	$ 124,301
Less: accumulated depreciation	(92,539)	(95,310)
Total property and equipment, net	27,378	28,991
Network equipment
Property and equipment, net
Property and equipment, gross	105,760	107,916
Computer equipment and software
Property and equipment, net
Property and equipment, gross	8,711	9,801
Furniture and fixtures
Property and equipment, net
Property and equipment, gross	703	2,432
Leasehold improvements
Property and equipment, net
Property and equipment, gross	4,587	3,969
Other equipment
Property and equipment, net
Property and equipment, gross	$ 156	$ 183

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation — network	$ 16,277	$ 18,138	$ 18,032
Operating expense depreciation	$ 2,313	$ 2,376	$ 2,438

Line of Credit (Details) - Revolving Credit Facility - Credit Agreement		12 Months Ended
	Nov. 02, 2015	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Feb. 28, 2018 USD ($)	Jan. 31, 2018 USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing amount					$ 20,000,000	$ 10,000,000
Borrowing capacity limit, percent of accounts receivable		80.00%
Debt term		1 year
Proceeds from line of credit		$ 0	$ 0
Current borrowing capacity		$ 20,000,000	10,000,000
Debt default basis spread on variable rate		3.00%
Commitment fee percentage paid at closing		5000000.00%
Interest expense, line of credit		$ 0	0	$ 205,000
Commitment fees amortization		86,000	$ 80,000	$ 321,000
Voting stock percentage in foreign subsidiaries	65.00%
Minimum cash and revolver availability		10,000,000
Minimum cash at lender		$ 5,000,000
Adjusted quick ratio		1.0
Prime Rate
Line of Credit Facility [Line Items]
Variable rate		0.25%

Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other current liabilities
Accrued compensation and benefits	$ 7,528	$ 12,181
Accrued cost of revenue	2,361	3,170
Accrued legal fees	22	383
Deferred rent	145	434
Other accrued expenses	2,866	2,339
Total other current liabilities	$ 12,922	$ 18,507

Contingencies (Details) $ in Thousands	Apr. 09, 2018 USD ($) installment_payment	Aug. 01, 2016 USD ($) installment_payment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Settlement receivable			$ 5,960	$ 0
Settled Litigation \| Akamai '703 Litigation
Loss Contingencies [Line Items]
Provision for litigation		$ 54,000
Number of quarterly installment payments for litigation settlement \| installment_payment		12
Litigation reserve, remaining amount due			9,000
Settled Litigation \| Akamai Litigation
Loss Contingencies [Line Items]
Number of quarterly installment payments for litigation settlement \| installment_payment	5
Period of agreement to not sue	3 years
Amount awarded from other party	$ 14,900
Settlement receivable			$ 5,960

Net Income (Loss) per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

^[1]

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Net income (loss)

$ (5,193)

$ (272)

$ 15,159

$ 149

$ (912)

$ (1,756)

$ (1,625)

$ (3,337)

$ 9,842

$ (7,630)

$ (73,925)

Basic weighted average outstanding shares of common stock (in shares)

113,578

112,760

111,356

110,761

112,114

108,814

104,350

Dilutive effect of stock options, restricted stock units, and other equity incentive plans (in shares)

7,896

Diluted weighted average outstanding shares of common stock (in shares)

113,578

112,760

120,033

118,909

120,010

108,814

104,350

Basic net income (loss) per share (in dollars per share)

$ (0.05)

$ 0.00

$ 0.14

$ 0.00

$ 0.09

$ (0.07)

$ (0.71)

Diluted net income (loss) per share (in dollars per share)

$ (0.05)

$ 0.00

$ 0.13

$ 0.00

$ 0.08

$ (0.07)

$ (0.71)

[1]	During the quarter ended June 30, 2018, we recorded $14,900 of settlement and patent license income related to the definitive settlement and patent license agreement entered into with Akamai.

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

Net Income (Loss) per Share - Dilutive Common Stock (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded outstanding options and restricted stock units	3,739	6,055	1,307
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded outstanding options and restricted stock units	0	80	114
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded outstanding options and restricted stock units	3,288	2,643	71
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Excluded outstanding options and restricted stock units	451	3,332	1,122

Stockholders' Equity (Details) - USD ($)	12 Months Ended
Stockholders' Equity (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 14, 2017	Feb. 12, 2014
Equity, Class of Treasury Stock [Line Items]
Stock repurchased and retired during period (shares)	1,000,000	0	0
Payments for repurchase of common stock	$ 3,800,000	$ 0	$ 0
Issuance of preferred stock authorized (shares)	7,500,000	7,500,000
Employee stock
Equity, Class of Treasury Stock [Line Items]
Discount from market price for employees (percent)	15.00%
Issuance of common stock under employee stock purchase plan (in shares)	596,000	687,000	1,324,000
Proceeds received for stock issued	$ 2,157,000	$ 1,574,000	$ 1,498,000
Common Stock reserved for future options and restricted stock awards (shares)	34,000
Employee funds held by Company for future purchase of shares	$ 293,000
2007 Equity Incentive Plan
Equity, Class of Treasury Stock [Line Items]
Shares authorized for issuance under Restated 2007 Plan (in shares)	8,336,000
2017 Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program authorized amount				$ 25,000,000
2012 Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program authorized amount					$ 15,000,000
Remaining authorized repurchase amount				$ 9,500,000

Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 144,145	$ 137,568	$ 198,097
Other comprehensive gain (loss) before reclassifications	(1,705)
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive (loss) gain, net of tax	(1,705)	2,710	(226)
Ending balance	165,151	144,145	137,568
Foreign Currency
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(8,259)
Other comprehensive gain (loss) before reclassifications	(1,733)
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive (loss) gain, net of tax	(1,733)
Ending balance	(9,992)	(8,259)
Unrealized Gains (Losses) on Available for Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(69)
Other comprehensive gain (loss) before reclassifications	28
Amounts reclassified from accumulated other comprehensive loss	0
Other comprehensive (loss) gain, net of tax	28
Ending balance	(41)	(69)
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(8,328)	(11,038)	(10,812)
Ending balance	$ (10,033)	$ (8,328)	$ (11,038)

Share-Based Compensation - Stock Option Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock option activity
Number of shares, beginning balance	16,963	16,017	14,667
Number of shares, granted	2,126	2,082	3,589
Number of shares, exercised	(1,479)	(384)	(850)
Number of shares, cancelled	(667)	(752)	(1,389)
Number of shares, ending balance	16,943	16,963	16,017
Weighted Average Exercise Price
Weighted average exercise price, beginning balance (in dollars per share)	$ 2.99	$ 3.18	$ 3.33
Weighted average exercise price, granted (in dollars per share)	3.50	4.56	2.22
Weighted average exercise price, exercised (in dollars per share)	2.72	2.79	1.46
Weighted average exercise price, canceled (in dollars per share)	5.23	11.04	3.38
Weighted average exercise price, ending balance (in dollars per share)	$ 2.99	$ 2.99	$ 3.18

Share-Based Compensation - Outstanding Stock Options (Details) - Stock Options shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Outstanding stock options
Options outstanding, number of options outstanding \| shares	16,943
Options exercisable, number of options exercisable \| shares	12,782
$ 0.00 — $ 1.50
Outstanding stock options
Exercise price range, lower range limit (in dollars per share)	$ 0
Exercise price range, upper range limit (in dollars per share)	$ 1.50
Options outstanding, number of options outstanding \| shares	0
Options outstanding, weighted average remaining contractual life	0 years
Options outstanding, weighted average exercise price (in dollars per share)	$ 0.00
Options exercisable, number of options exercisable \| shares	0
Options exercisable, weighted average exercise price (in dollars per share)	$ 0.00
$ 1.51 — $ 3.00
Outstanding stock options
Exercise price range, lower range limit (in dollars per share)	1.51
Exercise price range, upper range limit (in dollars per share)	$ 3.00
Options outstanding, number of options outstanding \| shares	11,142
Options outstanding, weighted average remaining contractual life	5 years 8 months
Options outstanding, weighted average exercise price (in dollars per share)	$ 2.26
Options exercisable, number of options exercisable \| shares	9,977
Options exercisable, weighted average exercise price (in dollars per share)	$ 2.26
$ 3.01 — $ 4.50
Outstanding stock options
Exercise price range, lower range limit (in dollars per share)	3.01
Exercise price range, upper range limit (in dollars per share)	$ 4.50
Options outstanding, number of options outstanding \| shares	3,379
Options outstanding, weighted average remaining contractual life	7 years 7 months
Options outstanding, weighted average exercise price (in dollars per share)	$ 3.59
Options exercisable, number of options exercisable \| shares	1,268
Options exercisable, weighted average exercise price (in dollars per share)	$ 3.77
$ 4.51 — $ 6.00
Outstanding stock options
Exercise price range, lower range limit (in dollars per share)	4.51
Exercise price range, upper range limit (in dollars per share)	$ 6.00
Options outstanding, number of options outstanding \| shares	2,209
Options outstanding, weighted average remaining contractual life	5 years 8 months
Options outstanding, weighted average exercise price (in dollars per share)	$ 5.32
Options exercisable, number of options exercisable \| shares	1,324
Options exercisable, weighted average exercise price (in dollars per share)	$ 5.25
$ 6.01 — $ 7.50
Outstanding stock options
Exercise price range, lower range limit (in dollars per share)	6.01
Exercise price range, upper range limit (in dollars per share)	$ 7.50
Options outstanding, number of options outstanding \| shares	28
Options outstanding, weighted average remaining contractual life	1 year 9 months
Options outstanding, weighted average exercise price (in dollars per share)	$ 6.24
Options exercisable, number of options exercisable \| shares	28
Options exercisable, weighted average exercise price (in dollars per share)	$ 6.24
$ 7.51 — $ 15.00
Outstanding stock options
Exercise price range, lower range limit (in dollars per share)	7.51
Exercise price range, upper range limit (in dollars per share)	$ 15
Options outstanding, number of options outstanding \| shares	185
Options outstanding, weighted average remaining contractual life	2 years 1 month
Options outstanding, weighted average exercise price (in dollars per share)	$ 8.05
Options exercisable, number of options exercisable \| shares	185
Options exercisable, weighted average exercise price (in dollars per share)	$ 8.05

Share-Based Compensation - Fair Value of Options Awarded (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Grant date fair value of option
Expected volatility	51.05%	53.94%	58.30%
Expected term, years	6 years 1 month 40 days	6 years 1 month 17 days	5 years 11 months 27 days
Risk-free interest	2.91%	2.11%	1.76%
Expected dividends	0.00%	0.00%	0.00%

Share-Based Compensation - RSUs Outstanding (Details) - shares shares in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
RSUs with service-based vesting conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units outstanding	4,248	5,809	6,673

Share-Based Compensation - RSU Activity (Details) - Restricted stock units - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted stock units (RSUs) outstanding
Number of units, beginning balance	5,809	6,673	6,265
Number of units, granted	2,475	3,435	5,024
Number of units, vested	(3,501)	(4,004)	(3,753)
Number of units, forfeitures	(535)	(295)	(863)
Number of units, ending balance	4,248	5,809	6,673
Weighted Average Fair Value
Weighted average fair value, beginning balance (in dollars per share)	$ 2.68	$ 2.16	$ 2.70
Weighted average fair value, granted (in dollars per share)	3.88	3.05	1.76
Weighted average fair value, vested (in dollars per share)	2.49	2.16	2.49
Weighted average fair value, canceled (in dollars per share)	3.39	2.23	2.29
Weighted average fair value, ending balance (in dollars per share)	$ 3.45	$ 2.68	$ 2.16

Share-Based Compensation - Allocation of Share-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of share-based compensation expense
Share-based compensation	$ 15,830	$ 12,744	$ 13,459
Cost of services
Components of share-based compensation expense
Share-based compensation	1,815	1,450	1,493
General and administrative expense
Components of share-based compensation expense
Share-based compensation	8,458	6,502	7,070
Sales and marketing expense
Components of share-based compensation expense
Share-based compensation	2,837	2,470	2,792
Research and development expense
Components of share-based compensation expense
Share-based compensation	2,720	2,322	2,104
Stock options
Components of share-based compensation expense
Share-based compensation	4,238	3,813	3,742
Restricted stock units
Components of share-based compensation expense
Share-based compensation	10,753	8,402	9,121
ESPP
Components of share-based compensation expense
Share-based compensation	$ 839	$ 529	$ 596

Share-Based Compensation - Additional Information (Details) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
	Sep. 18, 2015	Dec. 31, 2018 USD ($) Participant $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Exercise price of incentive stock options granted under the Plan may not be granted		100.00%
Weighted average period of unvested stock compensation		2 years 1 month 25 days
Unrecognized share-based compensation expense total		$ 19,264
Number of shares issued to program participants \| shares		2,126	2,082	3,589
Stock for Compensation Program
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock for compensation program, percentage of compensation, election option one	0.00%
Stock for compensation program, percentage of compensation, election option two	25.00%
Stock for compensation program, percentage of compensation, election option three	50.00%	50.00%
Stock for compensation program, percentage of compensation, election option four	75.00%
Stock for compensation program, percentage of compensation, election option five	100.00%
Stock for Bonus Program
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock for compensation program, percentage of compensation, election option three		50.00%
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Weighted-average grant-date fair value of options granted (in dollars per share) \| $ / shares		$ 1.82	$ 2.38	$ 1.22
Total intrinsic value of the options exercised		$ 3,171	$ 594	$ 411
Aggregate intrinsic value of options outstanding		$ 1,436
Weighted average remaining contractual options period exercisable		5 years
Unrecognized share-based compensation expense related to stock options		$ 7,203
Weighted average period of unvested stock compensation		2 years 4 months 4 days
Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Weighted average period of unvested stock compensation		2 years 1 month 1 day
Weighted-average grant-date fair value of RSUs granted \| $ / shares		$ 3.88	$ 3.05	$ 1.76
Total intrinsic value of the units vested		$ 14,659	$ 13,531	$ 6,314
Aggregate intrinsic value of restricted stock units outstanding		9,939
Unrecognized share-based compensation expense related to restricted stock awards		$ 12,061
Chief Executive Officer And Direct Reports \| Stock for Compensation Program
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock for compensation program, number of participants \| Participant		3
Number of shares issued to program participants \| shares		335
Stock issued during period, share-based compensation		$ 572
Chief Executive Officer And Direct Reports \| Stock for Bonus Program
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock issued during period, share-based compensation		$ 2,037

Related Party Transactions (Details) - Goldman, Sachs & Co. Affiliates		1 Months Ended	5 Months Ended	12 Months Ended
	Jun. 14, 2007	Jul. 31, 2006 $ / shares shares	Mar. 31, 2018 shares	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Ownership percentage				1.00%	14.00%	28.00%
Series B Preferred Stock
Related Party Transaction [Line Items]
Aggregate issuance of Series B Preferred Stock (in shares)		39,869,960
Aggregate issuance of Series B Preferred Stock, purchase price (in dollars per share) \| $ / shares		$ 3.26
Basis of conversion of Series B Convertible Preferred Stock into shares of common stock				on a 1-for-1 share basis
Common Stock
Related Party Transaction [Line Items]
Number of shares sold by related party			30,272,493
Preferred Stock conversion ratio	1

Leases and Purchase Commitments - Operating Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Future minimum lease payments over remaining lease periods
2019	$ 2,266
2020	1,309
2021	730
2022	55
2023	0
Thereafter	0
Total minimum payments	$ 4,360

Leases and Purchase Commitments - Purchase Commitments (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Minimum purchase commitments
2019	$ 22,078
2020	3,685
2021	904
2022	244
2023	0
Thereafter	0
Total minimum payments	$ 26,911

Leases and Purchase Commitments - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Rent and operating expense relating to operating lease agreements and bandwidth and co-location agreements	$ 59,593	$ 56,785	$ 59,415

Concentrations (Details)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2018

USD ($)

Sep. 30, 2018

USD ($)

Jun. 30, 2018

USD ($)

^[1]

Mar. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Sep. 30, 2017

USD ($)

Jun. 30, 2017

USD ($)

Mar. 31, 2017

USD ($)

Dec. 31, 2018

USD ($)

country

Dec. 31, 2017

USD ($)

country

Dec. 31, 2016

USD ($)

country

Geographic concentration | Total revenue

$ 43,992

$ 49,315

$ 50,249

$ 52,114

$ 48,186

$ 46,069

$ 45,370

$ 44,735

$ 195,670

$ 184,360

$ 168,234

Number of countries accounting for 10% or more of revenue | country

100.00%

United States / Americas | Geographic concentration | Total revenue

Amazon | Customer concentration | Total revenue

$ 113,102

$ 112,166

$ 94,105

Revenues from External Customers and Long-Lived Assets [Line Items]

30.00%

17.00%

[1]	During the quarter ended June 30, 2018, we recorded $14,900 of settlement and patent license income related to the definitive settlement and patent license agreement entered into with Akamai.

Income Taxes - Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income (loss) before income taxes:
United States	$ 8,648	$ (8,963)	$ (74,130)
Foreign	1,732	1,759	808
Income (loss) before income taxes	$ 10,380	$ (7,204)	$ (73,322)

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 0	$ 0	$ 0
State	32	40	103
Foreign	489	711	330
Total current	521	751	433
Deferred:
Federal	8	(34)	15
State	3	3	0
Foreign	6	(294)	155
Total deferred	17	(325)	170
Total provision	$ 538	$ 426	$ 603

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. federal statutory tax rate	$ 2,180	$ (2,521)	$ (25,663)
Valuation allowance	(1,845)	(30,938)	23,184
Foreign income taxes	150	(179)	338
State income taxes	51	90	100
Non-deductible expenses	85	149	323
Uncertain tax positions	0	(20)	(136)
Non-deductible officer compensation	688	638	0
Share-based compensation	(745)	873	2,439
Federal rate change impact	0	32,415	0
Other	(26)	(81)	18
Total provision	$ 538	$ 426	$ 603
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. federal statutory tax rate	21.00%	35.00%	35.00%
Valuation allowance rate	(17.80%)	429.50%	(31.60%)
Foreign income taxes rate	1.50%	2.50%	(0.50%)
State income taxes rate	0.50%	(1.20%)	(0.20%)
Non-deductible expenses rate	0.80%	(2.10%)	(0.40%)
Uncertain tax positions rate	0.00%	0.30%	0.20%
Non-deductible officer compensation rate	6.60%	(8.90%)	0.00%
Share-based compensation rate	(7.20%)	(12.10%)	(3.30%)
Federal rate change rate	0.00%	(450.00%)	0.00%
Other rate	(0.20%)	1.10%	0.00%
Provision for income taxes rate	5.20%	(5.90%)	(0.80%)

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Share-based compensation	$ 6,552	$ 6,047
Net operating loss and tax credit carry-forwards	46,569	43,543
Legal settlement	2,281	6,738
Deferred revenue	418	1,084
Accounts receivable reserves	188	224
Fixed assets	2,687	2,222
Other	177	311
Total deferred tax assets	58,872	60,169
Deferred tax liabilities:
Prepaid expenses	(306)	(81)
Other	(107)	(8)
Total deferred tax liabilities	(413)	(89)
Valuation allowance	(57,149)	(58,718)
Net deferred tax assets	$ 1,310	$ 1,362

- Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 1,817	$ 1,830
Additions for tax positions related to current year	0	0
Additions for tax positions related to prior years	20	26
Settlements	(34)	0
Adjustment related to foreign currency translation	0	3
Reductions related to the lapse of applicable statute of limitations	(3)	(42)
Reduction for tax positions of prior years	0	0
Ending balance	$ 1,800	$ 1,817

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred tax assets with no valuation allowance	$ 1,600,000
Unrecognized tax benefits	1,800,000	$ 1,817,000	$ 1,830,000
Unrecognized tax benefits that would impact effective tax rate	203,000
Interest and penalties accrual related to unrecognized tax benefits	7,000
Decrease in unrecognized tax benefits	5,000
Tax benefit related to the re-measurement of a deferred tax liability on a long-lived asset	41,000
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	186,100,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	126,400,000
State tax credit carryforward	$ 0

401(k) Plan (Details) - USD ($) $ in Thousands	12 Months Ended
401(k) Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
401(k) Plan (Textual) [Abstract]
Percentage of compensation for dollar-for-dollar match on eligible employee's deferral	3.00%
Percentage of match on next 2% of employee deferrals	50.00%
Percentage of employee compensation for 50% match on employees deferral	2.00%
Matching contributions	$ 1,423	$ 1,327	$ 1,345

Segment Reporting and Geographic Information - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018 Segment Location
Segment Reporting [Abstract]
Number of industry segment \| Segment	1
Number of geographic areas \| Location	3

Segment Reporting and Geographic Information - Revenue by Geography (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

^[1]

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Revenues from External Customers and Long-Lived Assets [Line Items]

$ 43,992

$ 49,315

$ 50,249

$ 52,114

$ 48,186

$ 46,069

$ 45,370

$ 44,735

$ 195,670

$ 184,360

$ 168,234

Americas

Revenues from External Customers and Long-Lived Assets [Line Items]

118,462

116,112

100,421

EMEA

Revenues from External Customers and Long-Lived Assets [Line Items]

38,015

37,212

31,326

Asia Pacific

Sales Revenue, Net | Geographic Concentration Risk

$ 39,193

$ 31,036

$ 36,487

Revenues from External Customers and Long-Lived Assets [Line Items]

Sales Revenue, Net | Geographic Concentration Risk | Americas

100.00%

Revenues from External Customers and Long-Lived Assets [Line Items]

Sales Revenue, Net | Geographic Concentration Risk | EMEA

61.00%

63.00%

60.00%

Revenues from External Customers and Long-Lived Assets [Line Items]

Sales Revenue, Net | Geographic Concentration Risk | Asia Pacific

19.00%

20.00%

18.00%

Revenues from External Customers and Long-Lived Assets [Line Items]

Sales Revenue, Net | Geographic Concentration Risk | United States / Americas

20.00%

17.00%

22.00%

Revenues from External Customers and Long-Lived Assets [Line Items]

Sales Revenue, Net | Geographic Concentration Risk | United Kingdom / EMEA

$ 113,102

$ 112,166

$ 94,105

Revenues from External Customers and Long-Lived Assets [Line Items]

Sales Revenue, Net | Geographic Concentration Risk | Japan / Asia Pacific

26,672

22,456

15,290

Revenues from External Customers and Long-Lived Assets [Line Items]

$ 20,452

$ 18,585

$ 19,967

[1]	During the quarter ended June 30, 2018, we recorded $14,900 of settlement and patent license income related to the definitive settlement and patent license agreement entered into with Akamai.

Segment Reporting and Geographic Information - Assets by Geography (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Asset Reconciling Item [Line Items]
Long-lived Assets	$ 27,378	$ 28,991	$ 30,352
Americas
Segment Reporting, Asset Reconciling Item [Line Items]
Long-lived Assets	18,349	17,119	18,665
International
Segment Reporting, Asset Reconciling Item [Line Items]
Long-lived Assets	$ 9,029	$ 11,872	$ 11,687

Fair Value Measurements - Schedule of Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Total assets measured at fair value	$ 25,875	$ 35,233
Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	752	6,789
Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	25,123	28,444
Significant Unobservable Inputs (Level 3)
Assets:
Total assets measured at fair value	0	0
Money market funds
Assets:
Total assets measured at fair value	752	6,789
Money market funds \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	752	6,789
Money market funds \| Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	0	0
Money market funds \| Significant Unobservable Inputs (Level 3)
Assets:
Total assets measured at fair value	0	0
Certificate of deposit
Assets:
Total assets measured at fair value	40	40
Certificate of deposit \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	0	0
Certificate of deposit \| Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	40	40
Certificate of deposit \| Significant Unobservable Inputs (Level 3)
Assets:
Total assets measured at fair value	0	0
Corporate notes and bonds
Assets:
Total assets measured at fair value	25,083	28,404
Corporate notes and bonds \| Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	0	0
Corporate notes and bonds \| Significant Other Observable Inputs (Level 2)
Assets:
Total assets measured at fair value	25,083	28,404
Corporate notes and bonds \| Significant Unobservable Inputs (Level 3)
Assets:
Total assets measured at fair value	$ 0	$ 0

Fair Value Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Cash equivalent maturity date	3 months

Quarterly Financial Results (unaudited) (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Quarterly results of operations