PROS (PRO) 10-K 15 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 11, 2019	Jun. 30, 2018
Entity Information [Line Items]
Entity Registrant Name	PROS HOLDINGS, INC.
Entity Central Index Key	1,392,972
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		37,475,474
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 842,462,432

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 295,476	$ 160,505
Trade and other receivables, net of allowance of $978 and $760, respectively	41,822	32,484
Deferred Costs, Current	4,089	3,137
Prepaid and other current assets	4,756	5,930
Total current assets	346,143	202,056
Property and equipment, net	14,676	14,007
Deferred Costs, Noncurrent	13,373	3,194
Intangible Assets, Net (Excluding Goodwill)	19,354	26,929
Goodwill	38,231	38,458
Other Assets, Noncurrent	5,190	4,039
Total assets	436,967	288,683
Current liabilities:
Accounts payable	6,934	2,976
Accrued liabilities	9,506	6,733
Accrued payroll and other employee benefits	22,519	16,712
Deferred Revenue, Current	99,262	75,604
Convertible Debt, Current	136,529	0
Total current liabilities	274,750	102,025
Deferred Revenue, Noncurrent	17,903	19,591
Convertible Debt, Noncurrent	88,661	213,203
Other Liabilities, Noncurrent	754	843
Total liabilities	382,068	335,662
Commitments and contingencies (Note 17)
Stockholders' equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized none issued	0	0
Common stock, $0.001 par value, 75,000,000 shares authorized; 41,573,491 and 36,356,760 shares issued, respectively; 37,155,906 and 31,939,175 shares outstanding, respectively	42	36
Additional paid-in capital	364,877	207,924
Treasury stock, 4,417,585 common shares, at cost	(13,938)	(13,938)
Retained Earnings (Accumulated Deficit)	(292,708)	(238,185)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(3,374)	(2,816)
Total stockholders' equity	54,899	(46,979)
Total liabilities and stockholders' equity	$ 436,967	$ 288,683

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for bad debts	$ 978,000	$ 760,000
Preferred stock - par value	$ 0.001	$ 0.001
Preferred stock - shares authorized	5,000,000	5,000,000
Preferred stock - shares issued	0	0
Common stock - par value	$ 0.001	$ 0.001
Common stock - shares authorized	75,000,000	75,000,000
Common stock - shares issued	41,573,491	36,356,760
Common stock - shares outstanding	37,155,906	31,939,175
Treasury stock - shares	4,417,585	4,417,585

Condensed Consolidated Statemen

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Subscription	$ 95,192	$ 60,539	$ 38,158
Maintenance and support	64,760	69,408	68,565
Total subscription, maintenance and support revenue	159,952	129,947	106,723
License	3,516	5,562	11,814
Services	33,556	33,307	34,739
Total revenue	197,024	168,816	153,276
Cost of revenue:
Cost of Subscription	35,368	27,858	17,379
Cost of Maintenance and support	11,602	11,693	13,681
Cost of subscription, maintenance and support	46,970	39,551	31,060
Cost of License	251	282	246
Cost of Services	29,958	28,733	32,047
Cost of Revenue	77,179	68,566	63,353
Gross profit	119,845	100,250	89,923
Operating Expenses
Selling and Marketing Expense	72,006	68,116	63,980
General and Administrative Expense	41,302	40,336	38,537
Research and development	55,657	56,021	52,804
Business Combination, Acquisition Related Costs	95	720	0
Income from operations	(49,215)	(64,943)	(65,398)
Other income (expense):
Convertible debt interest and amortization	(16,986)	(13,218)	(9,319)
Other Nonoperating Income (Expense)	2,155	384	(38)
Income (loss) before income tax provision	(64,046)	(77,777)	(74,755)
Income Tax Expense (Benefit)	200	149	470
Net Income (Loss) Attributable to Parent	$ (64,246)	$ (77,926)	$ (75,225)
Net earnings (loss) per share:
Earnings Per Share, Basic and Diluted	$ (1.86)	$ (2.46)	$ (2.47)
Weighted average number of shares:
Weighted Average Number of Shares Outstanding, Basic and Diluted	34,465	31,627	30,395
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	$ (558)	$ 2,107	$ (594)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0	(13)	6
Other Comprehensive Income (Loss), Net of Tax	(558)	2,094	(588)
Other comprehensive income, net of tax:
Comprehensive income (loss)	$ (64,804)	$ (75,832)	$ (75,813)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net Income (Loss) Attributable to Parent	$ (64,246)	$ (77,926)	$ (75,225)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, Depletion and Amortization	13,055	10,531	9,507
Amortization of Financing Costs and Discounts	12,027	9,264	6,439
Share-based compensation	21,453	22,796	20,466
Deferred income tax	(463)	(520)	40
Provision for doubtful accounts	212	0	174
Gain (Loss) on Disposition of Assets	37	59	19
Changes in operating assets and liabilities:
Accounts and unbilled receivables	(9,550)	2,022	5,671
Increase (Decrease) in Other Operating Assets	(4,086)	0	0
Prepaid expenses and other assets	87	(3,715)	(915)
Accounts payable	3,931	700	(2,905)
Accrued liabilities	2,764	(1,055)	2,801
Accrued payroll and other employee benefits	5,830	(2,344)	5,195
Deferred revenue	24,652	14,875	14,388
Net cash (used in) provided by operating activities	5,703	(25,313)	(14,345)
Investing activities:
Purchases of property and equipment	(1,475)	(1,286)	(7,241)
Payments to Acquire Other Investments	(45)	0	(2,000)
Payments to Acquire Businesses, Net of Cash Acquired	0	(34,130)	0
Capitalized Software Development Costs for Software Sold to Customers	(4,613)	(2,797)	(1,048)
Payments to Acquire Intangible Assets	(125)	(125)	(1,625)
Payments to Acquire Short-term Investments	0	0	(154,990)
Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities	0	15,992	141,500
Net cash (used in) provided by investing activities	(6,258)	(22,346)	(25,404)
Financing activities:
Exercise of stock options	1,142	6,331	889
Proceeds from Stock Plans	1,720	1,535	1,090
Tax withholding related to net share settlement of restricted stock units	(9,410)	(7,375)	(5,467)
Proceeds from Issuance of Common Stock	141,954	0	0
Repayments of Notes Payable	(54)	(209)	(196)
Proceeds from Convertible Debt	0	93,500	0
Net cash (used in) provided by financing activities	135,352	90,654	(3,684)
Effect of Exchange Rate on Cash and Cash Equivalents	174	(529)	(298)
Net change in cash and cash equivalents	134,971	42,466	(43,731)
Cash and cash equivalents:
Beginning of period	160,505	118,039	161,770
End of period	295,476	160,505	118,039
Income Taxes Paid, Net	(262)	(271)	968
Interest Paid	(5,252)	(4,013)	(3,182)
Capital Expenditures Incurred but Not yet Paid	247	38	378
Convertible Debt [Member]
Financing activities:
Payments of Debt Issuance Costs	0	(2,978)	0
Revolving Credit Facility [Member]
Financing activities:
Payments of Debt Issuance Costs	$ 0	$ (150)	$ 0

Consolidated Statement of Share

Consolidated Statement of Shareholders Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income, net of tax [Member]
Common stock - shares outstanding, beginning balance at Dec. 31, 2015		29,738,976
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	$ 55,414	$ 34	$ 158,674	$ (13,938)	$ (85,034)	$ (4,322)
Treasury stock - shares, beginning balance at Dec. 31, 2015				4,417,585
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues		96,870
Proceeds from Stock Options Exercised	889		889
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		682,112
Stock Issued During Period, Value, Restricted Stock Award, Gross	(5,466)	$ 1	(5,467)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		65,693
Proceeds from Stock Plans	1,090		1,090
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	20,492		20,492
Share-based Compensation	20,466
Other Comprehensive Income (Loss), Net of Tax	(588)					(588)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(594)
Net Income (Loss) Attributable to Parent	(75,225)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest					(75,225)
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	(3,394)	$ 35	175,678	$ (13,938)	(160,259)	(4,910)
Treasury stock - shares, ending balance at Dec. 31, 2016				4,417,585
Common stock - shares outstanding, ending balance at Dec. 31, 2016		30,583,651
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues		651,607
Exercise of stock options		$ 1
Proceeds from Stock Options Exercised	6,331		6,330
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		611,708
Stock Issued During Period, Value, Restricted Stock Award, Gross	(7,375)		(7,375)
Stock Issued During Period, Shares, Employee Stock Purchase Plans		92,209
Proceeds from Stock Plans	1,535		1,535
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	22,910		22,910
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	8,846		8,846
Share-based Compensation	22,796
Other Comprehensive Income (Loss), Net of Tax	2,094					2,094
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	2,107
Net Income (Loss) Attributable to Parent	(77,926)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest					(77,926)
Stockholders' Equity Attributable to Parent at Dec. 31, 2017	$ (46,979)	$ 36	207,924	$ (13,938)	(238,185)	(2,816)
Treasury stock - shares, ending balance at Dec. 31, 2017	4,417,585			4,417,585
Common stock - shares outstanding, ending balance at Dec. 31, 2017	31,939,175	31,939,175
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues		161,997
Exercise of stock options		$ 1
Proceeds from Stock Options Exercised	$ 1,142		1,141
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		609,188
Stock Issued During Period, Value, Restricted Stock Award, Gross	$ (9,410)	$ 1	(9,411)
Stock Issued During Period, Shares, Employee Stock Purchase Plans	75,546	75,546
Proceeds from Stock Plans	$ 1,720		1,720
Stock Issued During Period, Shares, Secondary Offering		4,370,000
Stock Issued During Period, Value, Secondary Offering		$ 4	141,950
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	21,553		21,553
Cumulative effect of adoption of section 606	9,723				9,723
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt	141,954
Share-based Compensation	21,453
Other Comprehensive Income (Loss), Net of Tax	(558)					(558)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(558)
Net Income (Loss) Attributable to Parent	(64,246)				(64,246)
Stockholders' Equity Attributable to Parent at Dec. 31, 2018	$ 54,899	$ 42	$ 364,877	$ (13,938)	$ (292,708)	$ (3,374)
Treasury stock - shares, ending balance at Dec. 31, 2018	4,417,585			4,417,585
Common stock - shares outstanding, ending balance at Dec. 31, 2018	37,155,906	37,155,906

Organization and Nature of Oper

Organization and Nature of Operations	12 Months Ended
	Dec. 31, 2018
Organization and Nature of Operations [Abstract]
Organization and nature of operations	Organization and Nature of Operations PROS Holdings, Inc., a Delaware corporation, through its operating subsidiaries (collectively, the "Company"), provides artificial intelligence ("AI") solutions that power commerce in the digital economy by providing fast, frictionless and personalized buying experiences. PROS solutions enable dynamic buying experiences for both business-to-business ("B2B") and business-to-consumer ("B2C") companies across industry verticals. Companies can use the Company's dynamic pricing optimization, sales effectiveness, revenue management and commerce solutions to assess their market environments in real time to deliver customized prices and offers. The Company's solutions enable buyers to move fluidly across its customers’ direct sales, online, mobile and partner channels with personalized experiences regardless of which channel those customers choose. The Company's decades of data science and AI expertise are infused into its solutions and are designed to reduce time and complexity through actionable intelligence. The Company provides standard configurations of its software based on the industries it serves and offers professional services to configure these solutions to meet the specific needs of each customer.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies Principles of Consolidation and Basis of Presentation These Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances have been eliminated in consolidation. The Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP"). Changes in Accounting Policies The Company has consistently applied the accounting policies described in this Note 2 to all periods presented in these Consolidated Financial Statements, except for the Company's adoption of certain accounting standards described in more detail under " Recently adopted accounting pronouncements " in this Note 2 below. Dollar Amounts The dollar amounts presented in the tabular data within these footnote disclosures are stated in thousands of dollars, except per share amounts, or as noted within the context of each footnote disclosure. Use of Estimates The preparation of these Consolidated Financial Statements in conformity with GAAP requires the Company to make certain estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenues, costs and expenses during the reporting period. These estimates include, but are not limited to, unbilled receivables and deferred revenue, the determination of the period of benefit for deferred commissions, receivables, allowance for doubtful accounts, useful lives of assets, depreciation and amortization, the fair value of assets acquired and liabilities assumed for business combinations, income taxes and deferred tax asset valuation, valuation of stock options, other current liabilities and accrued liabilities. Actual results could differ from those estimates and such differences could be material to the Company's consolidated financial position and results of operations. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase, or the ability to be settled in cash within a period of three months, to be cash equivalents, except for commercial paper which is classified as short-term investments, if any. The Company has a cash management program that provides for the investment of excess cash balances, primarily in short-term money market instruments. Trade and Other Receivables Trade and other receivables are primarily comprised of trade receivables, net of allowance for doubtful accounts, contract assets and unbilled receivables. The Company's standard billing terms require payment within thirty to sixty days from the date of invoice. The carrying value of such receivables, net of the allowance for doubtful accounts, represents their estimated net realizable value. The Company estimates its allowance for doubtful accounts for specific trade receivable balances based on historical collection trends, the age of outstanding trade receivables, existing economic conditions, and any financial security associated with the receivables. Contract assets represent conditional rights to consideration that have been recognized as revenue in advance of billing the customer. Unbilled receivables represent unconditional rights to consideration arising from contingent revenue, that have been recognized as revenue in advance of billing the customer. Equity Investments Investments in equity securities of privately held companies without readily determinable fair value, where the Company does not exercise significant influence over the investee, are recorded at cost, less impairment and adjusted for subsequent observable price changes obtained from orderly transactions for identical or similar investments issued by the same investee. Adjustments resulting from impairment, fair value, or observable price changes are accounted for in the Consolidated Statements of Comprehensive Income (Loss). Financial Instruments The carrying amount of the Company’s financial instruments, which include cash equivalents, receivables and accounts payable, and cost method investment approximates their fair values at December 31, 2018 and 2017 . For additional information on the Company’s fair value measurements, see Note 9 to the Consolidated Financial Statements. Prepaid Expenses and Other Assets Prepaid expenses and other assets consist primarily of prepaid third-party cloud infrastructure costs and license fees, deferred project costs and prepaid income taxes. Property and Equipment, Net Property and equipment are recorded at cost, less accumulated depreciation. Maintenance, repairs and minor replacements are charged to expense as incurred. Significant renewals and betterments are capitalized. Depreciation on property and equipment, with the exception of leasehold improvements, is recorded using the straight-line method over the estimated useful lives of the assets. Depreciation on leasehold improvements is recorded using the shorter of the lease term or useful life. When property is retired or disposed of, the cost and related accumulated depreciation are removed from the accounts and any resulting gains or losses are reflected in the Consolidated Statements of Comprehensive Income (Loss) in the period of disposal. Internal-Use Software Costs incurred to develop internal-use software during the application development stage are capitalized, stated at cost, and depreciated using the straight-line method over the estimated useful lives of the assets. Application development stage costs generally include salaries and personnel costs and third-party contractor expenses associated with internal-use software development, configuration and coding. Capitalization of such costs begins when the preliminary project stage is complete and ceases at the point in which the project is substantially complete and is ready for its intended purpose. Capitalized internal-use software is included in property and equipment, net in the Consolidated Balance Sheets. Deferred Costs Sales commissions earned by the Company's sales representatives are considered incremental and recoverable costs of obtaining a customer contract. Sales commissions are deferred and amortized on a straight-line basis over the period of benefit, which the Company has determined to be five to eight years. The Company determined the period of benefit by taking into consideration its customer contracts, expected renewals of those customer contracts (as the Company currently does not pay an incremental sales commission), the Company's technology and other factors. The Company also defers amounts earned by employees other than sales representatives who earn incentive payments under compensation plans that are also tied to the value of customer contracts acquired. Deferred Implementation Costs The Company capitalizes certain contract fulfillment costs, including personnel and other costs (such as hosting, employee salaries, benefits and payroll taxes), that are associated with arrangements where professional services are not distinct from other undelivered obligations in its customer contracts. The Company analyzes implementation costs and capitalizes those costs that are directly related to customer contracts, that are expected to be recoverable, and that enhance the resources which will be used to satisfy the undelivered performance obligations in those contracts. Deferred implementation costs are amortized ratably over the remaining contract term once the revenue recognition criteria for the respective performance obligation has been met and revenue recognition commences. Deferred implementation costs are included in prepaid and other current assets and other assets, noncurrent in the Consolidated Balance Sheets. Amortization of deferred implementation costs is included in cost of subscription and cost of services revenues in the Consolidated Statements of Comprehensive Income (Loss). Deferred Revenue Deferred revenue primarily consists of customer invoicing in advance of revenues being recognized. The Company generally invoices its customers annually in advance for subscription services and maintenance and support services. Deferred revenue that is anticipated to be recognized during the next twelve-month period is recorded as current deferred revenue and the remaining portion is recorded as noncurrent deferred revenue. Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever an event or change in circumstances indicates that the carrying amount of an asset or group of assets may not be recoverable. The impairment review includes comparison of future cash flows expected to be generated by the asset or group of assets with the associated assets’ carrying value. If the carrying value of the asset or group of assets exceeds its expected future cash flows (undiscounted and without interest charges), an impairment loss is recognized to the extent that the carrying amount of the asset exceeds its fair value. The Company recorded no impairment charges in the year ended December 31, 2018 , 2017 and 2016 . Intangible Assets and Goodwill Intangible assets that have finite lives are amortized over their useful lives and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. During this review, the Company reevaluates the significant assumptions used in determining the original cost and estimated lives of long-lived assets. Although the assumptions may vary from asset to asset, they generally include operating results, changes in the use of the asset, cash flows and other indicators of value. Management then determines whether the remaining useful life continues to be appropriate or whether there has been an impairment of long-lived assets based primarily upon whether expected future undiscounted cash flows are sufficient to support the assets’ recovery. If impairment exists, the Company would adjust the carrying value of the asset to fair value, generally determined by a discounted cash flow analysis. Goodwill represents the excess of the purchase consideration over the net of the acquisition-date fair value of identifiable assets acquired, including identifiable intangible assets, and liabilities assumed in connection with business combinations. Goodwill is not amortized, but is assessed for impairment as of November 30 of each fiscal year, or more frequently if events or changes in circumstances indicate that the fair value of the Company’s sole reporting unit has been reduced below its carrying value. When conducting the annual goodwill impairment assessment, a three step process is used. The first step is to perform an optional qualitative evaluation as to whether it is more likely than not that the fair value of the Company’s sole reporting unit is less than its carrying value, using an assessment of relevant events and circumstances. In performing this assessment, the Company is required to make assumptions and judgments including but not limited to an evaluation of macroeconomic conditions as they relate to the business, industry and market trends, as well as the overall future financial performance of the reporting unit and future opportunities in the markets in which it operates. If it is determined that it is not more likely than not that the fair value of the reporting unit is less than its carrying value, no additional tests are required to be performed in assessing goodwill for impairment. However, if the Company concludes otherwise or elects not to perform the qualitative assessment, the Company performs a second step, consisting of a quantitative assessment of goodwill impairment. This quantitative assessment requires us to estimate the fair value of the reporting unit and compare the estimated fair value to its respective carrying value (including goodwill) as of the date of the impairment test. The third step, employed for the reporting unit failing the second step, is used to measure the amount of any potential impairment and compares the implied fair value of the reporting unit with the carrying amount of goodwill. Based on the results of the qualitative review of goodwill performed as of November 30, 2018, the Company did not identify any indicators of impairment. As such, the second and third steps described above were not necessary. Research and Development Research and development costs for software sold to customers are expensed as incurred. These costs include salaries and personnel costs, including employee benefits, third-party contractor expenses, software development tools, an allocation of facilities and depreciation expenses and other expenses in developing new solutions and upgrading and enhancing existing solutions. Software Development Costs Capitalization of software development costs for software to be sold, leased, or otherwise marketed begins upon the establishment of technological feasibility, which is generally the completion of a working prototype that has been certified as having no critical bugs and is a release candidate. Amortization begins once the software is ready for its intended use, generally based on the pattern in which the economic benefits will be consumed. To date, software development costs incurred between completion of a working prototype and general availability of the related product have not been material. Treasury Stock The Company is authorized to make treasury stock purchases in the open market pursuant to the share repurchase program, which was approved by its Board of Directors on August 28, 2008. The Company accounts for the purchase of treasury stock under the cost method. For additional information on the Company’s stock repurchase program, see Note 11 to the Consolidated Financial Statements. There were no treasury stock repurchases for the years ended December 31, 2018 , 2017 and 2016 . Revenue Recognition The Company derives its revenues primarily from subscription services, professional services, perpetual licensing of its software products and associated software maintenance and support services. The Company determines revenue recognition through the following steps: • Identification of the contract, or contracts, with a customer; • Identification of the performance obligations in the customer contract(s); • Determination of the transaction price; • Allocation of the transaction price to each performance obligation in the customer contract(s); and • Recognition of revenue when, or as, the Company satisfies a performance obligation. Subscription services revenue Subscription services primarily include customer access to one or more of the Company's cloud applications and associated customer support. Subscription services revenue is generally recognized ratably over the contractual subscription term, beginning on the date that the Company's subscription service is made available to the customer. The Company's subscription contracts do not provide customers with the right to take possession of the software supporting the service and, as a result, are accounted for as service contracts. The Company's subscription contracts are generally two to five years in length, billed annually in advance, and non-cancelable. Maintenance and support revenue Maintenance and support revenue includes post-implementation customer support for on-premise licenses and the right to unspecified software updates and enhancements. The Company recognizes revenue from maintenance and support arrangements ratably over the period in which the services are provided. The Company's maintenance and support contracts are generally one to three years in length, billed annually in advance, and non-cancelable. License revenue Licenses to on-premise software provide the customer with a right to use, in the customer's environment, the Company's software as it exists when made available to the customer. License revenue from customer contracts with distinct on-premises licenses is recognized at the point in time when the software is made available to the customer. For customer contracts that contain license and professional services that are not considered distinct, both the license and professional services are determined to be a single performance obligation and the revenue is recognized over time based upon the Company's efforts to satisfy the performance obligation. Professional services revenue Professional services revenue primarily consists of fees for deployment and configuration services, as well as training services. Professional services revenues are generally recognized as the services are rendered for time and material contracts, or on a proportional performance basis for fixed fee contracts. The majority of the Company's professional services contracts are on a fixed fee basis. Training revenues are recognized as the services are rendered. Significant judgment is required in determining whether professional services contained in a customer subscription services contract are capable of being distinct and are separately identifiable in the customer contract. Professional services determined to be distinct are accounted for as a separate performance obligation and revenue is recognized as the services are performed. If the professional services are not determined to be distinct, the professional services and the subscription services are accounted for as a single performance obligation and revenue is recognized over the contractual term of the subscription beginning on the date that subscription services are made available to the customer. Customer contracts with multiple performance obligations A portion of the Company's customer contracts contain multiple performance obligations. Significant judgment is required in determining whether multiple performance obligations contained in a single customer contract are capable of being distinct and are separately identifiable. An obligation determined to be distinct is accounted for as a separate performance obligation and revenue for that separate performance obligation is recognized when, or as, the Company satisfies the performance obligation. If obligations are not determined to be distinct, those obligations are accounted for as a single, combined performance obligation. The transaction price is allocated to each performance obligation on a relative standalone selling price basis. Disaggregation of revenue The Company categorizes revenue from external customers by geographic area based on the location of the customer's headquarters. For additional information regarding the Company's revenue by geography, see Note 18 to the Consolidated Financial Statements. Foreign Currency The Company has contracts denominated in foreign currencies and therefore a portion of the Company’s revenue is subject to foreign currency risks. Gains and losses from foreign currency transactions, such as those resulting from the settlement of receivables, are classified in other income (expense), net included in the accompanying Consolidated Statements of Comprehensive Income (Loss). The functional currency of PROS France SAS ("PROS France") is the Euro. The financial statements of this subsidiary are translated into U.S. dollars using period-end rates of exchange for assets and liabilities, historical rates of exchange for equity, and average rates of exchange for the period for revenue and expenses. Translation gains (losses) are recorded in accumulated other comprehensive income (loss) as a component of stockholders’ equity. Noncash Share-Based Compensation The Company has two noncash share-based compensation plans, the 2007 Equity Incentive Plan ("2007 Stock Plan") and the 2017 Equity Incentive Plan ("2017 Stock Plan"), which authorize the discretionary granting of various types of stock awards to key employees, officers, directors and consultants. The 2007 Stock Plan expired in March 2017. The 2017 Stock Plan serves as the successor to the 2007 Stock Plan and was adopted in May 2017. The Company may provide noncash share-based compensation through the grant of: (i) restricted stock awards; (ii) restricted stock unit awards - time and market-based ("RSUs"); (iii) stock options; (iv) stock appreciation rights ("SARs"); (v) phantom stock; and (vi) performance awards, such as market stock units ("MSUs"). To date, the Company has granted stock options, SARs, RSUs, time-based and market-based, and MSUs. The Company issues common stock from its pool of authorized stock upon exercise of stock options, settlement of SARs and MSUs or upon vesting of RSUs. The following table presents the number of awards outstanding for each award type as of December 31, 2018 and 2017 (in thousands): Year Ended December 31, Award type 2018 2017 Stock options — 135 Restricted stock units (time-based) 1,969 2,133 Restricted stock units (market-based) 215 345 Stock appreciation rights 287 356 Market stock units 419 387 Stock options. The Company did not grant stock options during 2018 and 2017 . The fair value of each stock option was estimated on the date of grant using the Black-Scholes option pricing model. Restricted stock units. The fair value of the RSUs (time-based and performance-based) is based on the closing price of the Company’s stock on the date of grant and is amortized over the vesting period. RSUs include (i) time-based awards, and (ii) market-based awards in which the number of shares that vest are based upon attainment of target average per share closing price over a requisite trading period. Market-based RSUs vest if the average trailing closing price of the Company's common stock meets certain minimum performance hurdles for at least 105 calendar days prior to September 9, 2020, with 25% vesting at $27 , an additional 25% vesting at $33 , and the remaining 50% vesting at $41 . The Company estimates the fair value and the derived service period of the market-based RSUs on the date of grant using a Monte Carlo simulation model. The model requires the use of a number of assumptions including the expected volatility of the Company's stock, its risk-free interest rate and expected dividends. The Company's expected volatility at the date of grant is based on the historical volatility of the Company over the performance period. Stock appreciation rights. SARs will be settled in stock at the time of exercise and vest over four years from the date of grant. The Company used the Black-Scholes option pricing model to estimate the fair value of its SARs. The determination of the fair value of SARs utilizing the Black-Scholes model is affected by the Company’s stock price and a number of assumptions, including expected volatility, expected life, delivery of risk-free interest rate and expected dividends. The Company estimates the expected volatility of common stock at the date of grant based on a combination of its historical volatility and the average volatility of comparable companies. The expected life of the SARs noncash share-based payment awards is a historical weighted average of the expected lives of similar securities of comparable public companies. The risk-free interest rate assumption is based on observed interest rates appropriate for the terms of the Company’s awards. The dividend yield assumption is based on the Company's expectation of paying no dividends. Market stock units. MSUs are performance-based awards that vest based upon the Company’s relative shareholder return. The actual number of MSUs that will be eligible to vest is based on the total shareholder return of the Company relative to the total shareholder return of the Russell 2000 Index ("Index") over a three year period ending December 31, 2017, March 2, 2018, February 28, 2019, February 28, 2020, October 9, 2020 and December 31, 2020 ("Performance Period"), respectively. The MSUs vested on January 1, 2018 and March 3, 2018, and will vest on March 1, 2019, March 1, 2020, October 9, 2020 and January 10, 2021, respectively. The maximum number of shares issuable upon vesting is 200% of the MSUs initially granted based on the average price of the Company's common stock relative to the Index during the Performance Period. The Company estimates the fair value of MSUs on the date of grant using a Monte Carlo simulation model. The determination of fair value of the MSUs is affected by the Company’s stock price and a number of assumptions including the expected volatility of the Company’s stock and the Index, its risk-free interest rate and expected dividends. The Company’s expected volatility at the date of grant was based on the historical volatilities of the Company and the Index over the Performance Period. As the Company issues stock options and SARs, it evaluates the assumptions used to value its stock option awards and SARs. If factors change and the Company employs different assumptions, noncash share-based compensation expense may differ significantly from what has been recorded in the past. If there are any modifications or cancellations of the underlying unvested securities, the Company may be required to accelerate, increase or cancel any remaining unearned noncash share-based compensation expense. Future noncash share-based compensation expense and unearned noncash share-based compensation will increase to the extent that the Company grants additional equity awards to employees. At December 31, 2018 , there were an estimated $33.3 million of total unrecognized compensation costs related to noncash share-based compensation arrangements. These costs will be recognized over a weighted average period of 2.4 years. For further discussion of the Company’s noncash share-based compensation plans, see Note 13 to the Consolidated Financial Statements. Product Warranties For software-as-a-service application subscriptions, the Company generally issues a product warranty for the subscription term, depending on the contract. For on-premise software licenses, the Company generally issues a product warranty for 90 days following the first use of the software in a production environment, depending on the contract. In the Company’s experience, warranty costs have been insignificant. Income Taxes The Company uses the asset and liability method to account for income taxes, including recognition of deferred tax assets and liabilities for the anticipated future tax consequences attributable to differences between financial statement amounts and their respective tax basis. The Company reviews its deferred tax assets for recovery. A valuation allowance is established when the Company believes that it is more-likely than not that some portion of its deferred tax assets will not be realized. Changes in the valuation allowance from period to period are included in the Company’s tax provision in the period of change. The Company accounts for uncertain income tax positions recognized in an enterprise’s financial statements in accordance with the income tax topic of the ASC issued by the FASB. This interpretation requires companies to use a prescribed model for assessing the financial recognition and measurement of all tax positions taken or expected to be taken in its tax returns. This guidance provides clarification on recognition, classification, interest and penalties, accounting in interim periods, disclosures and transition. The Company recognized accrued interest and penalties related to income taxes as a component of income tax expense. For additional information regarding the Company’s income taxes, see Note 14 to the Consolidated Financial Statements. Segment Reporting The Company reports as one operating segment with the Chief Executive Officer ("CEO") acting as the Company’s chief operating decision maker. The Company’s CEO reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company has a single reporting unit, and there are no segment managers who are held accountable for operations, operating results or components below the consolidated unit level. Earnings Per Share The Company computes basic earnings (loss) per share by dividing net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding. Diluted earnings (loss) per share is computed by dividing net income (loss) attributable to common stockholders by the weighted average number of common shares and dilutive potential common shares then outstanding. Diluted earnings per share reflect the assumed conversion of all dilutive securities, using the treasury stock method. Dilutive potential common shares consist of shares issuable upon the exercise of stock options, shares of unvested RSUs, and settlement of SARs. When the Company incurs a net loss, the effect of the Company’s outstanding stock options, SARs, RSUs and MSUs are not included in the calculation of diluted earnings (loss) per share as the effect would be anti-dilutive. Accordingly, basic and diluted net loss per share are identical. Recently Adopted Accounting Pronouncements Topic 606 In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, " Revenue from Contracts with Customers (Topic 606) " ("Topic 606"). Topic 606 replaces the prior revenue recognition requirements in ASC 605, "Revenue Recognition" ("Topic 605" or "Prior Guidance") with a comprehensive revenue measurement and recognition standard, and expanded disclosure requirements. The new standard also provides guidance on the recognition of costs related to obtaining customer contracts. Topic 606 took effect in the first quarter of 2018, including interim periods within that reporting period. The Company adopted Topic 606 and applied Topic 606 to those contracts which were not complete as of January 1, 2018 using the modified retrospective method by recognizing the cumulative effect of initially applying the new standard as an adjustment to the opening balance of accumulated deficit, while prior period amounts are not adjusted and continue to be reported in accordance with the Company's historic accounting under the Prior Guidance. The most significant impact of Topic 606 relates to the Company's accounting for arrangements that include term-based software licenses bundled with maintenance and support, the deferral of incremental costs of obtaining a contract with a customer (including the period of amortization of such costs), and additional disclosures. Under the Prior Guidance, revenue attributable to term-based software licenses was recognized ratably over the term of the arrangement when vendor-specific objective evidence ("VSOE") did not exist for the undelivered maintenance and support element because it was not sold separately. Topic 606 does not require VSOE for undelivered elements to separate revenue for the delivered software licenses. Accordingly, under the new standard, the Company is required to recognize as revenue a portion of the arrangement fee upon delivery of the software license. As a result of applying Topic 606, the adjustment to the Company's opening balance sheet of the accumulated deficit for all revenue-related items was a decrease of approximately $2.7 million . Topic 606 also requires the Company to capitalize and amortize the costs to obtain a contract over the expected period of customer benefit. The Company previously capitalized and amortized only direct and incremental commission costs over the term of the related contract. The expected period of customer benefit determined under Topic 606 is longer than the typical two to five year term of the Company's contracts as required under the Prior Guidance. As a result of applying Topic 606, the Company recorded a decrease to the opening balance sheet of the accumulated deficit for costs to obtain a contract of approximately $7.0 million . Impact to previous reported results The Company applied Topic 606 using the modified retrospective method by recognizing the cumulative effect of initially applying Topic 606 as an adjustment to the opening balance sheet at January 1, 2018. Therefore, the comparative information has not been adjusted and continues to be reported under Topic 605. The differences between amounts reported under Topic 606 and what would have been reported Topic 605 are detailed below: December 31, 2018 (in thousands) As Reported Adjustments Balances Under Topic 605 Balance Sheets Trade and other receivables, net of allowance $ 41,822 $ (232 ) $ 41,590 Deferred costs, current 4,089 (30 ) 4,059 Deferred costs, noncurrent 13,373 (8,278 ) 5,095 Deferred revenue, current 99,262 2,120 101,382 Deferred revenue, noncurrent 17,903 1,088 18,99

Business Combination

Business Combination	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Business Combination On August 3, 2017, the Company acquired 100% of the issued and outstanding stock of Vayant Travel Technologies, Inc. ("Vayant"), a privately held company based in Sofia, Bulgaria, for total cash consideration, net of cash acquired, of approximately $34.1 million . Vayant is a cloud software company that provides advanced shopping, merchandising and inspirational travel solutions. The acquisition of Vayant strengthens the Company's modern commerce solutions for the travel industry and positions it to deliver greater value to its travel customers through an end-to-end offer optimization solution designed to help travel companies deliver personalized offers and expanded choices that drive loyalty and growth. For the year ended December 31, 2018 , the Company included $9.5 million of revenue and $4.8 million of net loss related to Vayant in its Consolidated Statement of Comprehensive Income (Loss). During the years ended December 31, 2018 and 2017 , the Company incurred acquisition-related costs of $0.1 million and $0.7 million , respectively, primarily related to advisory and legal fees, accounting and professional fees, and retention of key employees. All of the assets acquired and the liabilities assumed in the transaction have been recognized at their acquisition date fair values at August 3, 2017. The final allocation of the total purchase price for Vayant is as follows (in thousands): Cash $ 1,822 Other current assets 1,235 Noncurrent assets 86 Intangibles 18,600 Goodwill 17,052 Accounts payable and accrued liabilities (1,668 ) Deferred revenue (600 ) Deferred tax liability (526 ) Noncurrent liabilities (49 ) Net assets acquired $ 35,952 The following are the identifiable intangible assets acquired (in thousands) and their respective useful lives: Useful Life Amount (years) Developed technology $ 11,600 7 Customer relationships 7,000 5 Total $ 18,600 In performing the Vayant purchase price allocation, the Company considered, among other factors, its anticipated future use of the acquired assets, analysis of historical financial performance, and estimates of future cash flows from Vayant's products and services. The allocation resulted in acquired intangible assets of $18.6 million . The acquired intangible assets consisted of developed technology and customer relationships and were valued using the income approach in which the after-tax cash flows are discounted to present value. The cash flows are based on estimates used to price the transaction, and the discount rates applied were benchmarked with reference to the implied rate of return from the transaction model as well as the weighted average cost of capital. Additionally, the Company assumed certain liabilities in the Vayant acquisition, including deferred revenue to which a fair value of $0.6 million was ascribed using a cost-plus profit approach. The Company made a preliminary determination that $0.5 million of net deferred tax liabilities were assumed on the Vayant acquisition date. During the year ended December 31, 2018 , the Company made a final determination upon filing of the pre-acquisition period tax return that $0.8 million of net deferred tax liabilities were assumed on the Vayant acquisition date. The measurement period adjustment of $0.3 million to the deferred tax liabilities recorded during the year ended December 31, 2018 resulted in an increase to the goodwill, a release of additional valuation allowance and a benefit to the income tax provision. The excess of the purchase price over the estimated amounts of net assets as of the effective date of the acquisition was allocated to goodwill. The factors contributing to the recognition of the amount of goodwill are based on several strategic and synergistic benefits that are expected to be realized from the Vayant acquisition. These benefits include the expectation that the combined company’s complementary products will strengthen the Company's modern commerce solutions for the travel industry. The Company believes the combined company will benefit from a broader global presence and, with the Company’s direct sales force and larger channel coverage, significant cross-selling opportunities. None of the goodwill is expected to be currently deductible for tax purposes. In accordance with applicable accounting standards, goodwill will not be amortized but instead will be tested for impairment at least annually, or more frequently if certain indicators are present. In the event that the management of the combined company determines that the value of goodwill has become impaired, the combined company will incur a charge for the amount of the impairment during the fiscal quarter in which the impairment occurs. Pro Forma Financial Information The unaudited financial information in the table below summarizes the combined results of operations of the Company and Vayant, on a pro forma basis, as though the Company had acquired Vayant on January 1, 2016. The pro forma information for all periods presented also includes the effect of business combination accounting resulting from the acquisition, including amortization charges from acquired intangible assets. Year Ended December 31, (in thousands, except earnings per share) 2017 2016 Total revenue $ 173,866 $ 160,696 Net loss (81,476 ) (81,652 ) Earnings per share - basic and diluted $ (2.58 ) $ (2.69 )

Trade and Other Receivables, Ne

Trade and Other Receivables, Net	12 Months Ended
	Dec. 31, 2018
Accounts Receivable and Contracts in Progress [Abstract]
Loans, Notes, Trade and Other Receivables Disclosure [Text Block]	Receivables, Net Accounts receivable at December 31, 2018 and 2017 , consists of the following (in thousands): December 31, 2018 2017 Accounts receivable $ 38,876 $ 30,689 Unbilled receivables and contract assets 3,924 2,555 Total receivables 42,800 33,244 Less: Allowance for doubtful accounts (978 ) (760 ) Trade and other receivables, net $ 41,822 $ 32,484 The bad debt expense reflected in general and administrative expenses in the accompanying Consolidated Statements of Comprehensive Income (Loss) for the years ended December 31, 2018 , 2017 and 2016 , totaled approximately $0.2 million , zero and $0.2 million , respectively.

Deferred Costs (Notes)

Deferred Costs (Notes)	12 Months Ended
	Dec. 31, 2018
Deferred Costs [Abstract]
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block]	Deferred Costs Deferred costs, which primarily consist of deferred sales commissions, were $17.5 million and $6.3 million as of December 31, 2018 and December 31, 2017 , respectively. Amortization expense for the deferred costs was $3.0 million and $2.5 million for the year ended December 31, 2018 and 2017 , respectively. There was no impairment loss in relation to the costs capitalized for the periods presented.

Deferred Implementation costs (

Deferred Implementation costs (Notes)	12 Months Ended
	Dec. 31, 2018
Deferred Implementation Costs [Abstract]
Deferred Implementation Costs [Text Block]	Deferred Implementation Costs Deferred implementation costs, which related to certain customer contract fulfillment costs, were $3.9 million and $2.2 million as of December 31, 2018 and December 31, 2017 , respectively. Amortization expense for the deferred implementation costs was $0.6 million and $0.3 million for the year ended December 31, 2018 and 2017 , respectively. Deferred implementation costs are included in prepaid and other current assets and other assets, noncurrent in the Consolidated Balance Sheets. Amortization of deferred implementation costs is included in cost of subscription and cost of services revenues in the Consolidated Statements of Comprehensive Income (Loss). There was no impairment loss in relation to the costs capitalized for the periods presented.

Property and Equipment, net

Property and Equipment, net	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	Property and Equipment, Net Property and equipment, net as of December 31, 2018 and 2017 consists of the following: December 31, Estimated useful life 2018 2017 Furniture and fixtures 5-10 years $ 3,208 $ 2,958 Computers and equipment 3-5 years 19,644 18,950 Software 3-6 years 5,432 5,430 Capitalized internal-use software development costs 3 years 8,775 4,102 Leasehold improvements Shorter of lease term or useful life 5,587 5,650 Construction in progress 20 19 Property and equipment, gross 42,666 37,109 Less: Accumulated depreciation and amortization (27,990 ) (23,102 ) Property and equipment, net $ 14,676 $ 14,007 Depreciation and amortization was approximately $5.5 million , $5.4 million and $6.4 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. During the years ended December 31, 2018 , 2017 and 2016 , the Company disposed of approximately $0.5 million , $1.8 million and $2.3 million , respectively, of fully depreciated assets. During the years ended December 31, 2018 , 2017 and 2016 , the Company recognized immaterial amounts of loss on disposal of certain non-fully depreciated assets, respectively. As of December 31, 2018 and 2017 , the Company had approximately $14.0 million and $11.1 million , respectively, of fully depreciated assets in use. During the years ended December 31, 2018 and 2017 , the Company capitalized internal-use software development costs of approximately $4.7 million and $3.0 million , respectively, related to its subscription solutions. As of December 31, 2018 and 2017 , $2.8 million and $1.0 million , respectively, of capitalized internal-use software development costs were subject to amortization and $1.1 million and $0.1 million , respectively, of capitalized internal-use software development costs were included in accumulated depreciation and amortization for the years ended December 31, 2018 and 2017 . No impairment was recorded for the years ended December 31, 2018 , 2017 and 2016 .

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets [Abstract]
Goodwill and Intangible Assets Disclosure [Text Block]	Goodwill and Intangible Assets The change in the carrying amount of goodwill for the years ended December 31, 2018 and 2017 , was as follows (in thousands): Balance as of December 31, 2016 $ 20,096 Goodwill acquired 17,052 Foreign currency translation adjustments 1,310 Balance as of December 31, 2017 38,458 Purchase accounting adjustments 252 Foreign currency translation adjustments (479 ) Balance as of December 31, 2018 $ 38,231 The goodwill balance related to PROS France is denominated in Euro and the goodwill balance related to Vayant is denominated in the U.S. dollar. Intangible assets consisted of the following as of December 31, (in thousands): December 31, 2018 Weighted average useful life (years) Gross Carrying Amount Accumulated Amortization* Net Carrying Amount Developed technology 7 $ 25,584 $ 13,890 $ 11,694 Maintenance relationships 8 3,485 2,488 997 Customer relationships 6 11,802 6,884 4,918 Acquired technology 2 1,925 180 1,745 Total $ 42,796 $ 23,442 $ 19,354 *Cumulative foreign currency translation adjustments, reflecting movement in the currencies of the underlying entities, decreased total intangible assets by approximately $0.2 million as of December 31, 2018 . December 31, 2017 Weighted average useful life (years) Gross Carrying Amount Accumulated Amortization* Net Carrying Amount Developed technology 7 $ 26,023 $ 9,560 $ 16,463 Maintenance relationships 8 3,565 2,207 1,358 Customer relationships 6 11,840 4,482 7,358 Acquired technology 3 1,750 — 1,750 Total $ 43,178 $ 16,249 $ 26,929 *Cumulative foreign currency translation adjustments, reflecting movement in the currencies of the underlying entities, increased total intangible assets by approximately $0.7 million as of December 31, 2017 . Customer relationships are amortized over five or eight years. In December 2016, the Company purchased a technology-based intangible asset in connection with the equity securities investment made during the same period. The Company estimates that the intangible will be amortized over approximately a 2-year period. During the second half of 2017 and 2018, the Company purchased an additional technology-based intangible asset which is expected to be amortized over approximately a 1-year period. Intangible asset amortization expense for the years ended December 31, 2018 , 2017 and 2016 was $7.6 million , $5.2 million and $3.0 million , respectively. As of December 31, 2018 , the expected future amortization expense for the acquired intangible assets for each of the five succeeding years and thereafter was as follows (in thousands): Year Ending December 31, Amount 2019 $ 6,575 2020 5,791 2021 3,021 2022 1,921 2023 1,292 2024 and thereafter 754 Total amortization expense $ 19,354

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	Fair Value Measurements The Company adopted fair value measurements guidance for financial and nonfinancial assets and liabilities. The guidance defines fair value, establishes a framework for measuring fair value in GAAP and expands disclosures about fair value measurements. The guidance defines fair value as the price that would be received to sell an asset, or paid to transfer a liability, in an orderly transaction between market participants. The guidance establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows: Level 1 : Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 : Quoted prices for similar assets or liabilities in markets that are not active or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; and Level 3 : Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). A portion of the Company’s existing cash and cash equivalents are invested in short-term interest bearing obligations with original maturities less than 90 days, principally various types of money market funds. The Company does not enter into investments for trading or speculative purposes. At December 31, 2018 and 2017 , the Company had approximately $268.6 million and $131.4 million invested in treasury money market funds. The fair value of the treasury money market funds is determined based on quoted market prices, which represents level 1 in the fair value hierarchy as defined by Accounting Standard Codification ("ASC") 820, " Fair Value Measurement and Disclosure ." The fair value of the Company's Notes is classified in the level 2 hierarchy. See Note 15 for further detail regarding the Notes. In December 2016, the Company purchased $2.0 million equity securities in a privately held company. This investment is accounted for at cost, less impairment and adjusted for subsequent observable price changes obtained from orderly transactions for identical or similar investments issued by the same investee. The Company estimates fair value of its equity investment considering available information such as pricing in recent rounds of financing, current cash positions, earnings and cash flow forecasts, recent operational performance and any other readily available market data, which represents level 3 in the fair value hierarchy. An impairment charge to current earnings is recorded when the cost of the investment exceeds its fair value and this condition is determined to be other-than-temporary. As of December 31, 2018 and 2017 , the Company determined there were no other-than-temporary impairments on its equity investment.

Deferred Revenue and Performanc

Deferred Revenue and Performance Obligation (Notes)	12 Months Ended
	Dec. 31, 2018
Deferred Revenue and Performance Obligation [Abstract]
Deferred revenue and performance obligation [Text Block]	Deferred Revenue and Performance Obligations Deferred Revenue For the year ended December 31, 2018 and 2017 , the Company recognized approximately $74.6 million and $65.6 million , respectively, in each case of revenue that was included in the deferred revenue balances at the beginning of the respective periods and primarily related to subscription services, maintenance and support, and other services. Performance Obligations As of December 31, 2018 , the Company expects to recognize approximately $336.5 million of revenue from remaining performance obligations. The Company expects to recognize revenue on approximately $162.2 million of these performance obligations over the next 12 months, with the balance recognized thereafter.

Stockholders Equity

Stockholders Equity	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Attributable to Parent [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	Stockholders’ equity Equity Offering In August 2018, the Company completed a follow-on public offering of 3,800,000 shares of the Company's common stock at an offering price of $34 per share (the "Secondary Offering"). Additionally, as part of the Secondary Offering the underwriters exercised, in full, their over-allotment option to purchase an additional 570,000 shares of the Company's common stock at the offering price of $34 per share. The aggregate gross proceeds from the Secondary Offering, including the exercise of the over-allotment, were $148.6 million , and net proceeds received after underwriting fees and offering expenses were approximately $142.0 million . Stock Repurchase On August 25, 2008, the Company’s Board of Directors approved a stock repurchase program that authorized the Company to purchase up to $15.0 million of the Company’s outstanding shares of common stock. Under the board-approved repurchase program, share purchases may be made from time to time in the open market or through privately negotiated transactions depending on market conditions, share price, trading volume and other factors, and such purchases, if any, will be made in accordance with applicable insider trading and other securities laws and regulations. These repurchases may be commenced or suspended at any time or from time to time without prior notice. The Company did not repurchase any shares under this plan for the years ended December 31, 2018 and 2017 . The remaining amount available to purchase common stock under this plan was $10.0 million as of December 31, 2018 .

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings per Share	Earnings Per Share The following table sets forth the computation of basic and diluted earnings per share: For the Year Ended December 31, 2018 2017 2016 Numerator: Net loss $ (64,246 ) $ (77,926 ) $ (75,225 ) Denominator: Weighted average shares (basic) 34,465 31,627 30,395 Dilutive effect of stock options, restricted stock units and stock appreciation rights — — — Weighted average shares (diluted) 34,465 31,627 30,395 Basic earnings per share $ (1.86 ) $ (2.46 ) $ (2.47 ) Diluted earnings per share $ (1.86 ) $ (2.46 ) $ (2.47 ) Dilutive potential common shares consist of shares issuable upon the exercise of stock options, settlement of SARs, and the vesting of RSUs and MSUs. Potential common shares determined to be antidilutive and excluded from diluted weighted average shares outstanding were approximately 2.1 million , 2.0 million and 1.8 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Since the Company has the intention and ability to settle the principal amount of its Notes ( see Note 15 ) in cash, the treasury stock method is expected to be used for calculating any potential dilutive effect of the conversion spread on diluted net income per share, if applicable. The conversion spread will have a dilutive impact on diluted net income per share of common stock when the average market price of common stock for a given period exceeds the conversion price of $33.79 and $48.63 per share, for the 2019 Notes and 2047 Notes, respectively, and when the Company has net income.

Noncash Share-based Compensatio

Noncash Share-based Compensation	12 Months Ended
	Dec. 31, 2018
Noncash Share-based Compensation [Abstract]
Noncash Share-based Compensation	Noncash Share-Based Compensation Employee Noncash Share-based Compensation Plans The Company has two noncash share-based compensation plans, the 2007 Stock Plan and the 2017 Stock Plan (collectively the "Stock Plans"). These plans authorize the discretionary granting of various types of stock awards to key employees, officers, directors and consultants. The discretionary issuance of stock awards generally contains vesting provisions ranging from one to four years. 2007 Stock Plan. The Company’s 2007 Stock Plan expired in March 2017 for purposes of granting future equity awards. As of December 31, 2018 , the Company had outstanding equity awards to acquire 1,908,003 shares of its common stock held by the Company’s employees, directors and consultants under the 2007 Stock Plan (assuming MSU performance at 100% of the MSUs initially granted), and inclusive of zero stock options, 1,358,819 RSUs, 286,584 SARs and 262,600 MSUs. 2017 Stock Plan. The Company’s 2017 Stock Plan provides for the issuance of awards to employees, officers, directors and certain other individuals providing services to the Company are eligible to receive awards. The 2017 Stock Plan reserved an aggregate amount of 2,500,000 shares for issuance. The Company may provide these incentives through the grant of: (i) restricted stock awards; (ii) RSUs; (iii) stock options; (iv) SARs; (v) phantom stock; and (vi) performance awards, such as MSUs. As of December 31, 2018 , the Company had outstanding equity awards to acquire 981,746 shares of its common stock held by the Company’s employees, directors and consultants under the 2017 Stock Plan (assuming MSU performance at 100% of the MSUs initially granted), and inclusive of 825,178 RSUs and 156,568 MSUs. As of December 31, 2018 , 1,347,240 shares remain available for grant under the 2017 Stock Plan. As of December 31, 2018 , there were no options, SARs, restricted stock awards or phantom stock issued under the 2017 Stock Plan. Noncash share-based compensation expense for all noncash share-based payment awards granted is determined based on the grant date fair value of the award. The Company recognizes compensation expense, net of estimated forfeitures, which represents noncash share-based awards expected to vest on a straight-line basis over the requisite service period of the award, which is generally the vesting term. Noncash share-based awards typically vest over four years. Stock options are generally granted for a ten-year term. The Company estimates forfeiture rates based on its historical experience for grant years where the majority of the vesting terms have been satisfied. Changes in estimated forfeiture rates are recognized through a cumulative catch-up adjustment in the period of change and thus impact the amount of noncash share-based compensation expense to be recognized in future periods. Noncash share-based compensation expense is allocated to expense categories on the Consolidated Statements of Comprehensive Income (Loss). The following table summarizes noncash share-based compensation expense, net of amounts capitalized, for the years ended December 31, 2018 , 2017 and 2016 (in thousands). For the Year Ended December 31, 2018 2017 2016 Share-based compensation: Cost of revenue $ 1,721 $ 1,971 $ 2,267 Operating expenses: Selling and marketing 4,396 4,348 3,824 General and administrative 10,717 11,163 9,040 Research and development 4,619 5,314 5,335 Total included in operating expenses 19,732 20,825 18,199 Total share-based compensation expense $ 21,453 $ 22,796 $ 20,466 At December 31, 2018 , there was an estimated $33.3 million of total unrecognized compensation costs related to noncash share-based compensation arrangements. These costs will be recognized over a weighted average period of 2.4 years. Stock Options The following table summarizes the Company’s stock option activity for the year ended December 31, 2018 (number of shares and intrinsic value in thousands): Number of shares under option Weighted average exercise price Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Outstanding, December 31, 2017 135 $ 12.52 Granted — — Exercised (135) 12.52 Forfeited — — Expired — — Outstanding, December 31, 2018 — $ — 0 $ — Vested and exercisable at December 31, 2018 — $ — 0 $ — (1) The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the grant date fair value. For the years ended December 31, 2018 and 2017 , respectively, the Company did not grant any stock options. The total intrinsic value of stock options exercised for the years ended December 31, 2018 , 2017 and 2016 was $2.5 million , $7.2 million and $1.0 million , respectively. RSUs (time-based) The Company has granted RSUs under the Stock Plans. Time-based RSUs granted to employees, directors and consultants vest in equal annual installments over a one to four year period from the grant date. The following table summarizes the Company's unvested time-based RSUs as of December 31, 2018 , and changes during the year then ended (number of shares and intrinsic value in thousands): Number of shares Weighted average grant date fair value Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Unvested at December 31, 2017 2,133 $ 18.90 Granted 829 27.61 Vested (792 ) 20.49 Forfeited (201 ) 20.45 Unvested at December 31, 2018 1,969 $ 21.77 2.02 $ 61,827 Expected to vest at December 31, 2018 1,902 $ 21.65 2.00 $ 59,731 (1) The aggregate intrinsic value was calculated based on the fair value of the Company’s common stock on December 31, 2018 of $31.40 . The weighted average grant-date fair value of the time-based RSUs granted during the years ended December 31, 2018 , 2017 and 2016 was $27.61 , $21.63 and $11.69 , respectively. RSUs (market-based) During 2016, under the 2007 Stock Plan, the Company granted 460,000 RSUs with a market-based vesting condition to certain executive employees. These market-based RSUs will vest if the average trailing closing price of the Company's Common Stock meets certain minimum performance hurdles for at least 105 calendar days prior to September 9, 2020, with 25% vesting at $27 , an additional 25% vesting at $33 , and the remaining 50% vesting at $41 . The following table summarizes the Company's unvested market-based RSUs as of December 31, 2018 , and changes during the year then ended (number of shares and intrinsic value in thousands): Number of Weighted Weighted Aggregate Unvested at December 31, 2017 345 $ 10.86 Granted — — Vested (115 ) 12.61 Forfeited (15 ) 9.98 Unvested at December 31, 2018 215 $ 9.98 1.69 $ 6,751 Expected to vest at December 31, 2018 211 $ 9.98 1.69 $ 6,611 (1) The aggregate intrinsic value was calculated based on the fair value of the Company’s common stock on December 31, 2018 of $31.40 . The Company estimates the fair value and the derived service period of the market-based RSUs on the date of grant using a Monte Carlo simulation model. The model requires the use of a number of assumptions including the expected volatility of the Company's stock, its risk-free interest rate and expected dividends. The Company's expected volatility at the date of grant was based on the historical volatility of the Company over the performance period. The assumptions used to value the market-based RSUs granted in 2016 were as follows: December 31, 2016 Volatility 44.98% Risk-free interest rate 1.08% Dividend yield — The fair value of the market-based RSUs is expensed over the derived service period for each separate vesting tranche. The derived service period for the vesting tranches of the market-based RSUs ranges between 1.01 and 1.98 years. SARs The Company has granted SARs under the 2007 Stock Plan. The SARs will be settled in stock at the time of exercise and vest four years from the date of grant subject to the recipient’s continued employment with the Company. The number of shares issued upon the exercise of the SARs is calculated as the difference between the share price of the Company’s stock on the date of exercise and the date of grant multiplied by the number of SARs divided by the share price on the exercise date. The following table summarizes the Company's SARs activity for the year ended December 31, 2018 (number of shares and intrinsic value in thousands): Stock appreciation rights Weighted average exercise price Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Outstanding, December 31, 2017 356 $ 10.97 Granted — — Exercised (69 ) 11.17 Forfeited — — Expired — — Outstanding, December 31, 2018 287 $ 10.92 1.86 $ 5,869 Exercisable at December 31, 2018 287 $ 10.92 1.86 $ 5,869 Vested and expected to vest at December 31, 2018 287 $ 10.92 1.86 $ 5,869 (1) The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the exercise price of the underlying SARs. The Company did not grant SARs in 2018 , 2017 and 2016 . MSUs I n 2018 , 2017 and 2016 , the Company granted MSUs to certain executive employees under the Stock Plans. The MSUs are performance-based awards that vest based upon the Company’s relative shareholder return. The actual number of MSUs that will be eligible to vest is based on the total shareholder return of the Company relative to the total shareholder return of the Index over the three year Performance Period. The MSUs vested on January 1, 2018 and March 3, 2018, and will vest on March 1, 2019, March 1, 2020, October 9, 2020 and January 10, 2021, respectively. The MSUs maximum number of shares issuable upon vesting is 200% of the MSUs initially granted. The following table summarizes the Company's MSUs activity for the year ended December 31, 2018 (number of shares and intrinsic value in thousands): Number of unvested awards Weighted average grant date fair value Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Unvested at December 31, 2017 387 $ 23.48 Granted 117 38.18 Exercised (85 ) 31.83 Forfeited — — Expired — — Unvested at December 31, 2018 419 $ 25.90 1.10 $ 13,162 (1) The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the grant date fair value of the underlying MSUs. The Company estimates the fair value of MSUs on the date of grant using a Monte Carlo simulation model. The determination of fair value of the MSUs is affected by the Company's stock price and a number of assumptions including the expected volatilities of the Company's stock and the Index, its risk-free interest rate and expected dividends. The Company's expected volatility at the date of grant was based on the historical volatilities of the Company and the Index over the Performance Period. The Company did not estimate a forfeiture rate for the MSUs due to the limited size, the vesting period and nature of the grantee population and the lack of history of granting this type of award. Significant assumptions used in the Monte Carlo simulation model for MSUs granted during the years ended December 31, 2018 , 2017 and 2016 are as follows: For the Year Ended December 31, 2018 2017 2016 Volatility 43.67% 45.38% 44.06% Risk-free interest rate 2.12% 1.56% 1.04% Expected option life in years 2.97 3.07 2.93 Dividend yield — — — The assumptions related to fiscal year 2017 are presented on a weighted average basis for the various awards granted throughout the period. Employee Stock Purchase Plan In June 2013, the Board of Directors authorized an Employee Stock Purchase Plan ("ESPP") which provides for eligible employees to purchase shares on an after-tax basis in an amount between 1% and 10% of their annual pay: (i) on June 30 of each year at a 5% discount of the fair market value of the Company's common stock on January 1 or June 30, whichever is lower, and (ii) on December 31 of each year at a 5% discount of the fair market value of the Company's common stock on July 1 or December 31, whichever is lower. An employee may not purchase more than $5,000 in either of the six-month measurement periods described above or more than $10,000 annually. In November 2015, the Board of Directors amended the ESPP plan to increase the discount to 15% of the fair market value of the Company's common stock effective January 1, 2016. The amendment did not change the accounting treatment of the ESPP plan. During the year ended December 31, 2018 , the Company issued 75,546 shares under the ESPP. As of December 31, 2018 , 215,555 shares remain authorized and available for issuance under the ESPP. As of December 31, 2018 , the Company held approximately $0.9 million on behalf of employees for future purchases under the ESPP and this amount was recorded in accrued liabilities in the Company's Consolidated Balance Sheet.

Income Tax Disclosure

Income Tax Disclosure	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes The income tax provision consisted of the following for the years ended December 31, 2018 , 2017 and 2016 (in thousands): Year Ended December 31, 2018 2017 2016 Current: Federal $ (252 ) $ — $ 19 State and Foreign 663 669 402 411 669 421 Deferred: Federal (211 ) (488 ) 51 State — (32 ) (2 ) Income tax provision $ 200 $ 149 $ 470 The differences between the effective tax rates reflected in the total provision for income taxes and the U.S. federal statutory rate of 34% for the years ended December 31, 2018 , 2017 and 2016 , respectively, were as follows (in thousands): Year Ended December 31, 2018 2017 2016 Provision at the U.S. federal statutory rate $ (13,464 ) $ (26,443 ) $ (25,338 ) Increase (decrease) resulting from: State income taxes, net of federal taxes 46 18 3 Nondeductible expenses 414 373 457 Acquisition-related expense — 245 (4 ) Statutory to GAAP income adjustment (221 ) (77 ) (274 ) Foreign Tax Expense — — 2 Noncash share-based compensation (394 ) (3,405 ) 604 Other (153 ) — 49 Incremental benefits for tax credits (1,656 ) (1,711 ) (1,663 ) Change in tax rate/income subject to lower tax rates (1,824 ) 2,625 — Change related to prior tax years (4,800 ) (2,331 ) (856 ) Change related to US tax reform 1,835 31,359 — Change in valuation allowance 20,417 (504 ) 27,490 Income tax provision $ 200 $ 149 $ 470 The Company’s effective tax rate was 0% , 0% and (1)% for the years ended December 31, 2018 , 2017 and 2016 , respectively. During the year ended December 31, 2018 , the Company's effective tax rate was impacted primarily by changes in valuation allowance, foreign income taxes and other nondeductible expenses. On December 22, 2017, the Tax Cuts and Jobs Act ("TCJA") was signed into law in the U.S. and included a broad range of tax reform proposals affecting businesses, including corporate tax rates, business deductions, and international tax provisions. The Tax Cuts and Jobs Act reduced the U.S. corporate income tax rate to 21% effective January 1, 2018. The TCJA imposes a repatriation tax on any accumulated offshore earnings and profit. As of December 31, 2018 , the Company has reviewed the offshore earnings and profits and has no additional earnings to repatriate and has provided for no tax. . Based on the current accumulated loss in the foreign jurisdictions, the Company has no global intangible low-taxed income (“GILTI”) to report for December 31, 2018. The Company is under the revenue requirements to be subject to the base erosion and avoidance tax (“BEAT”), however, it has reviewed the transactions with foreign affiliates and does not believe there are payments that qualify under BEAT. The TCJA created the foreign derived intangible income (“FDII”) which allows for a deduction for certain types of foreign income. However, since the Company is in a current net operating loss position, no deduction is allowable for the current year. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), which allowed the Company to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. As a result, the Company previously provided a provisional estimate of the effect of the TCJA in the Consolidated Financial Statements. Upon filing of the 2017 income tax returns in the fourth quarter of 2018, the Company completed its analysis to determine the final effect of the TCJA on year end 2017. The Company recorded a final SAB 118 adjustment on the remeasurement of deferred taxes of approximately $1.8 million . This amount was fully offset by a change in valuation allowance. The tax effects of temporary differences and other tax attributes that give rise to significant portions of the deferred tax assets and liabilities as of December 31, 2018 and 2017 are as follows (in thousands): Year Ended December 31, 2018 2017 Noncurrent deferred taxes: Property and equipment $ (528 ) $ (847 ) Noncash share-based compensation 6,922 6,373 Disallowed interest expense 4,574 — Capitalized software (1,533 ) (1,397 ) Amortization (4,110 ) (5,096 ) R&E tax credit carryforwards 10,603 9,340 Deferred revenue 2,680 2,996 Federal Net Operating Losses ("NOLs") 58,601 46,907 State NOLs 2,319 1,050 State Credits 2,005 1,613 Foreign NOLs 8,945 9,057 Foreign tax credit carryforward 2,462 2,521 Other 1,291 1,425 Total noncurrent deferred tax assets 94,231 73,942 Less: Valuation allowance (94,231 ) (74,153 ) Total noncurrent deferred tax liability — (211 ) Total net deferred tax liability $ — $ (211 ) The net deferred tax liability is classified as other liabilities, noncurrent in the accompanying Consolidated Balance Sheets. The Company has federal and state net operating loss carryforwards related to current and prior year operations and acquisitions. Internal Revenue Code Section 382 ("Section 382") places certain limitations on the annual amount of U.S. net operating loss carryforwards that can be utilized when a change of ownership occurs. The Company believes the past acquisitions were changes in ownership pursuant to Section 382, subjecting federal acquired net operating losses to limitations. According to French tax law the net operating loss carryforwards are not subject to ownership change limitations. The U.S. federal and foreign net operating loss and R&E tax credit carryforward amount available to be used in future periods, taking into account the Section 382 annual limitation and current year losses, is approximately $310.0 million and $12.6 million , respectively. The Company’s net operating losses will begin to expire in 2024, R&E credits will begin to expire in 2031, and foreign tax credits will begin to expire in 2022. The U.S. net operating losses generated in 2018 have no expiration. Also included in net operating losses are $35.8 million of French carryforwards which have no expiration. As of December 31, 2014, the Company determined it was more likely than not that it would be unable to fully utilize the majority of its U.S. and state deferred tax assets. As a result, the Company had recorded a valuation allowance against those assets to the extent that they cannot be realized through net operating loss carrybacks to prior years. This valuation allowance is evaluated periodically and will be reversed partially or in whole if business results and the economic environment have sufficiently improved to support realization of some or all of the Company's deferred tax assets. In performing the analysis throughout 2018 , the Company determined that there was no sufficient positive evidence to outweigh the current and historic negative evidence to determine that it was more likely than not that the deferred assets would not be realized. Therefore, the Company continues to have a valuation allowance against net deferred tax assets as of December 31, 2018 and 2017 . During the year ended December 31, 2018 , the Company finalized the deferred tax liabilities assumed upon the acquisition of Vayant. An additional release of valuation allowance was recorded in that period. Undistributed earnings of the Company’s foreign subsidiaries are considered permanently reinvested and, accordingly, no provision for U.S. federal or state income taxes or non-U.S. withholding taxes has been provided thereon. The cumulative amount of positive undistributed earnings of the Company’s non-U.S. subsidiaries, if any, was minimal for the years ended December 31, 2018 and 2017 . The determination of the related deferred tax liability, which requires complex analysis of international tax situations related to repatriation, is not practical at this time. The Company is presently investing in international operations located in Europe, North America, and Australia. The Company is funding the working capital needs of its foreign operations through its U.S. operations. In the future, the Company plans to utilize its foreign undistributed earnings, as well as continued funding from its U.S. operations, to support its continued foreign investment. For each of the years ended December 31, 2018 , 2017 and 2016 , the Company had approximately $0.2 million of net unrecognized tax benefits which, if recognized, would impact the Company's effective tax rate. The Company recorded immaterial amounts for interest and penalties to tax expense as of December 31, 2018 , 2017 and 2016 , respectively. The Company believes that it is reasonably possible that there will be no change in the unrecognized tax benefits within the next twelve months. The Company is not subject to or aware of any forth-coming income tax examinations at this time. The Company has received a notice of a transfer pricing review by the Bulgarian tax authorities. At this time, there is no adjustment expected. The Company files tax returns in the U.S. and various foreign jurisdictions. The Company is subject to U.S. federal income tax examination for the calendar tax years 2016, 2015, 2014 and, 2013 and state and foreign income tax examination for various years depending on the statutes of limitation of those jurisdictions. The following table sets forth the changes to the Company's unrecognized tax benefit for the year ended December 31, 2018 , 2017 and 2016 (in thousands): Year Ended December 31, 2018 2017 2016 Beginning balance $ 183 $ 192 $ 192 Changes based on tax positions related to prior year — — — Changes due to settlement — (9 ) — Ending balance $ 183 $ 183 $ 192 The table above has been updated to reflect gross tax liability, exclusive of interest and penalties and other offsetting amounts.

Convertible debt (Notes)

Convertible debt (Notes)	12 Months Ended
	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term Debt [Text Block]	Convertible Senior Notes The Company issued $143.8 million principal amount of convertible senior notes in December 2014 (the "2019 Notes") and $106.3 million principal amount of convertible senior notes in June 2017 (the "2047 Notes" and collectively with the 2019 Notes, the "Notes"). The interest rates for the Notes are fixed at 2.0% per annum. Interest is payable semi-annually in arrears on June 1 and December 1 of each year, commencing on June 1, 2015 for the 2019 Notes, and on December 1, 2017 for the 2047 Notes. The 2019 Notes mature on December 1, 2019, unless redeemed or converted in accordance with their terms prior to such date. The 2047 Notes mature on June 1, 2047, unless repurchased, redeemed or converted in accordance with their terms prior to such date. Each $1,000 of principal of the 2019 Notes will initially be convertible into 29.5972 shares of the Company’s common stock, which is equivalent to an initial conversion price of approximately $33.79 per share. Each $1,000 of principal amount at maturity of the 2047 Notes had an issue price of $880 , and will initially be convertible into 20.5624 shares of the Company’s common stock, which is equivalent to an initial conversion price of approximately $48.63 per share. The initial conversion price for each of the Notes is subject to adjustment upon the occurrence of certain specified events. An amount equal to the difference between the issue price and the principal amount at maturity will accrete to the 2047 Notes in accordance with the schedule set forth in the 2047 Notes. The issue price plus such accreted amount of the 2047 Notes is referred to herein as the “accreted principal amount.” On June 1, 2022, the accreted principal amount will accrete to 100% of the principal amount at maturity. The Notes are each general unsecured obligations and rank senior in right of payment to all of the Company's indebtedness that is expressly subordinated in right of payment to the Notes, rank equally in right of payment with all of the Company's existing and future liabilities that are not so subordinated, are effectively junior to any of the Company's secured indebtedness to the extent of the value of the assets securing such indebtedness and are structurally subordinated to all indebtedness and other liabilities (including trade payables but excluding intercompany obligations owed to the Company or its subsidiaries). On or after September 1, 2019 to the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their 2019 Notes regardless of the contingent conversion conditions described herein. Upon conversion, the Company will pay or deliver cash, shares of its common stock or a combination of cash and shares of its common stock, at its election, as described in the indenture governing the 2019 Notes. On or before June 1, 2021, and subject to the satisfaction of certain conditions, the Company is entitled to elect to redeem all or any portion of the 2047 Notes at a redemption price equal to 100% of the accreted principal amount of the 2047 Notes, plus accrued and unpaid interest to, but excluding, the redemption date, if the daily volume weighted average price of the Company’s common stock is greater than or equal to 130% of the conversion price for at least 20 trading days during any 30 consecutive trading day period. After June 1, 2021, the Company will be entitled to elect to redeem all or any portion of the 2047 Notes (without regard to the price of the Company’s common stock) at a redemption price equal to the then current accreted principal amount of the 2047 Notes, plus accrued and unpaid interest to, but excluding, the redemption date. Holders may convert their 2019 Notes at their option at any time prior to the close of business on the business day immediately preceding September 1, 2019 only under the following circumstances: • during any calendar quarter commencing after the calendar quarter ending on March 31, 2015, if the last reported sale price of the common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; • during the five consecutive business day period immediately following any five consecutive trading day period in which the trading price per $1,000 principal amount of 2019 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company's common stock and the conversion rate on each such trading day; or • upon the occurrence of specified corporate events. Holders may convert their 2047 Notes at their option on any day prior to the close of business on the business day immediately preceding March 1, 2047 under the following circumstances: • during any calendar quarter commencing after the calendar quarter ending September 30, 2017, if the last reported sale price of the Company's common stock for 20 or more trading days (whether or not consecutive) in a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter exceeds 130% of the applicable conversion price in effect on each such trading day; • during the five consecutive business day period immediately following any five consecutive trading day period (the "Measurement Period") in which the trading price per 2047 Note for each day of that Measurement Period was less than 98% of the product of the last reported sale price of the Company's common stock and the conversion rate on each such day; or • upon the occurrence of specified corporate events. The 2047 Notes will also be convertible, regardless of the foregoing circumstances, at any time from, and including, March 1, 2047 until the close of business on the second scheduled trading day immediately preceding the applicable maturity date. Each holder of the 2047 Notes has the right to require the Company to repurchase for cash all or any portion of such holder's 2047 Notes on June 1, 2022 at a price per $1,000 principal amount of the 2047 Notes equal to the accreted principal amount at maturity plus accrued and unpaid interest to, but excluding, the repurchase date. If a fundamental change (as defined in the relevant indenture governing the applicable series of Notes) occurs prior to the maturity date, holders of each of the 2019 Notes and 2047 Notes may require the Company to repurchase all or a portion of their notes for cash at a repurchase price equal to 100% of the principal amount at maturity of the Notes, plus any accrued and unpaid interest to, but excluding, the repurchase date. If such a fundamental change occurs prior to June 1, 2022, holders of the 2047 Notes may also require the Company to repurchase all or a portion of their notes for cash at a repurchase price equal to the then current accreted principal amount of the Notes, plus any accrued and unpaid interest to, but excluding, the repurchase date. In addition, if specific corporate events occur prior to the applicable maturity date, the Company will be required to increase the conversion rate for holders who elect to convert their notes in certain circumstances. Holders who convert their 2047 Notes in connection with a Make-Whole Fundamental Change (as defined in the indenture governing the 2047 Notes) or in connection with a redemption of such 2047 Notes on or prior to June 1, 2021 will, under certain circumstances, be entitled to a make-whole premium in the form of an increase in the conversion rate determined by reference to a make-whole table set forth in such indenture. As of December 31, 2018 , the 2019 Notes and the 2047 Notes are not yet convertible. In accordance with accounting guidance on embedded conversion features, the Company valued and bifurcated the conversion options associated with each of the 2019 Notes and 2047 Notes from the respective host debt instrument, which is referred to as debt discount and recorded the conversion option of each of the Notes in stockholders’ equity. The equity component for each Note is not remeasured as long as such Note continues to meet the conditions for equity classification. In accounting for the transaction costs for each of the Notes issuances, the Company allocated the costs incurred to the liability and equity components in proportion to the allocation of the proceeds from issuance to the liability and equity components. Issuance costs attributable to the liability component, totaling $4.3 million for the 2019 Notes and $2.7 million for the 2047 Notes, are being amortized to expense over the expected life of each Note using the effective interest method. Issuance costs attributable to the equity component related to the conversion option, totaling $1.2 million for the 2019 Notes and $0.3 million for the 2047 Notes, were netted with the equity component in stockholders' equity. The Notes consist of the following (in thousands): December 31, 2018 December 31, 2017 Liability component: Principal $ 250,000 $ 250,000 Less: debt discount, net of amortization (24,810 ) (36,797 ) Net carrying amount $ 225,190 $ 213,203 Equity component (1) $ 37,560 $ 37,560 (1) Recorded within additional paid-in capital in the Consolidated Balance Sheet. As of December 31, 2018 , it included $28.7 million and $8.8 million related to the 2019 Notes and the 2047 Notes, respectively, net of $1.2 million and $0.3 million issuance cost in equity, respectively. The following table sets forth total interest expense recognized related to the Notes (in thousands): Year Ended December 31, 2018 2017 2.0% coupon $ 5,000 $ 3,991 Amortization of debt issuance costs 1,419 1,127 Amortization of debt discount 10,567 8,100 Total $ 16,986 $ 13,218 As of December 31, 2018 and December 31, 2017 , the fair value of the principal amount of the Notes was $251.5 million and $246.6 million , respectively. The estimated fair value was determined based on inputs that are observable in the market or that could be derived from, or corroborated with, observable market data, including the Company's stock price and interest rates, which represents level 2 in the fair value hierarchy. As of December 31, 2018 , the remaining life of the 2019 Notes and the 2047 Notes is approximately 11 months and 41 months, respectively. Note Hedge and Warrant Transactions Concurrently with the offering of the 2019 Notes, the Company entered into separate convertible note hedge (the "Note Hedge") and warrant (the "Warrant") transactions. Taken together, the purchase of the Note Hedge and the sale of the Warrant are intended to offset any actual dilution from the conversion of the 2019 Notes and to effectively increase the overall conversion price of the 2019 Notes from $33.79 to $45.48 per share. The total cost of the Note Hedge transaction was $29.4 million . The Company received $17.1 million in cash proceeds from the sale of the Warrant. Pursuant to the Warrants, if the average market value per share of the Company's common stock for the reporting period, as measured under the Warrant, exceeds the strike price of the Warrant, the Warrant will have a dilutive effect on the Company's earnings per share. Holders of the 2019 Notes and Note Hedge will not have any rights with respect to the Warrant, as the Note Hedge is not part of the 2019 Notes or the Warrant. The Warrant is not part of the 2019 Notes or Note Hedge. Both the Note Hedge and Warrant have been accounted for as part of additional paid-in capital.

Credit Facility

Credit Facility	12 Months Ended
	Dec. 31, 2018
Credit Facility Disclosure [Abstract]
Debt Disclosure [Text Block]	Credit Facility In January 2017, the Company, through its wholly owned subsidiary PROS, Inc., entered into an amendment to extend its $50 million secured Credit Agreement (the "Revolver") with the lenders party thereto and Wells Fargo Bank, National Association as agent for the lenders party thereto. The Revolver is for a five year term expiring in July 2022, with interest paid at the end of the applicable one month, three month or six month interest period at a rate per annum equal to LIBOR plus an applicable margin of 1.5% to 2.25% or the Federal Funds Rate plus an applicable margin of 1.5% to 2.25% . Borrowings under the Revolver are collateralized by a first priority interest in and lien on all of the Company's material assets . The Revolver contains affirmative and negative covenants, including covenants which restrict the ability of the Company to, among other things, create liens, incur additional indebtedness and engage in certain other transactions, in each case subject to certain exclusions. In addition, the Revolver contains certain financial covenants which become effective in the event the Company's liquidity falls below $50 million or upon the occurrence of an event of default. As of December 31, 2018 , the Company was in compliance with all financial covenants in the Revolver. As of December 31, 2018 and 2017 , $0.1 million and $0.2 million , respectively, of unamortized debt issuance costs related to the Revolver is included in prepaid and other current assets and other assets, noncurrent in the Consolidated Balance Sheets, respectively. For the years ended December 31, 2018 and 2017 , the Company recorded an immaterial amount of amortization of debt issuance cost which is included in other income (expense), net in the Consolidated Statements of Comprehensive Income (Loss). As of December 31, 2018 , the Company had no outstanding borrowings under the Revolver.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Litigation The Company is involved in various legal proceedings, claims and litigation which arise in the ordinary course of the business. The Company makes a provision for a liability relating to legal matters when it is both probable that a liability has been incurred and the amount of the loss can be reasonably estimated. These provisions are reviewed at least quarterly and adjusted to reflect the impacts of negotiations, settlements, rulings, advice of legal counsel and other information and events pertaining to a particular matter. The Company is not currently involved in any outstanding litigation that it believes, individually or in the aggregate, will have a material adverse effect on its business, financial condition, results of operations or cash flows. Purchase Commitments In the ordinary course of business, the Company enters into various purchase commitments for goods and services. In December 2018, the Company entered into a noncancelable agreement with a computing infrastructure vendor that expires in December 2021. The purchase commitment as of December 31, 2018 was $6.4 million for the remaining period under the three-year agreement. In June 2017, the Company entered into a noncancelable agreement with a computing infrastructure vendor that expires in June 2020. The purchase commitment as of December 31, 2018 was $12.6 million for the remaining period under the three-year agreement. Contractual Obligations In September 2018, the Company entered into an agreement of limited partnership related to a venture fund, pursuant to which the Company committed to make a capital contribution of $2.3 million within the next five years. Indemnification The Company’s software agreements generally include certain provisions for indemnifying customers against liabilities if the Company’s software solutions infringe a third party’s intellectual property rights. To date, the Company has not incurred any losses as a result of such indemnifications and has not accrued any liabilities related to such obligations in the Company’s Consolidated Financial Statements. Lease Commitments The Company leases office space and office equipment under non-cancelable operating leases that expire at various dates. The Company incurred approximately $4.3 million , $3.9 million and $4.1 million of total rent expense for the years ended December 31, 2018 , 2017 and 2016 , respectively. As of December 31, 2018 , the future minimum lease commitments related to lease agreements were as follows: Year Ending December 31, Amount 2019 $ 4,164 2020 1,649 2021 5,115 2022 6,181 2023 5,679 2024 and thereafter 57,365 Total minimum lease payments $ 80,153 The Company's headquarters are located in Houston, Texas, where it currently leases approximately 98,000 square feet of office space until October 31, 2019. In November, 2018, the Company entered into an agreement to lease approximately 118,000 square feet of office space for a new headquarter location which is expected to be occupied in the fourth quarter of 2019. The lease expires in August 2033. The Company also has smaller regional offices, including in London, England; Toulouse, France; San Francisco, California; and Sofia, Bulgaria. The Company leases approximately 3,000 square feet of office space in London, approximately 14,000 square feet of space in Toulouse, approximately 6,600 of space in San Francisco, and approximately 23,000 square feet of space in Sofia. The Company had no capital leases at December 31, 2018 and 2017 .

Segment and Geographical Inform

Segment and Geographical Information	12 Months Ended
	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Segment Reporting Disclosure [Text Block]	Segment and Geographic Information The Company operates as one segment with a single reporting unit. Operating segments are the components of an enterprise where separate financial information is evaluated regularly by the chief operating decision-maker, who is the Company's Chief Executive Officer, in deciding how to allocate resources and assessing financial performance. The Company's chief operating decision maker allocates resources and assesses performance based upon discrete financial information at the consolidated level. Revenue by Geography The Company presents financial information on a consolidated basis and does not assess the profitability of its geographic regions. Accordingly the Company does not attempt to comprehensively assign or allocate costs to these regions and does not produce reports for, or measure the performance of, its geographic regions based on any asset-based metrics. International revenue for the years ended December 31, 2018 , 2017 and 2016 , amounted to approximately $128.5 million , $105.7 million and $96.5 million , respectively, representing 65% , 63% and 63% , respectively, of annual revenue. The following geographic information is presented for the years ended December 31, 2018 , 2017 and 2016 . The Company categorizes geographic revenues based on the location of the customer’s headquarters. Year Ended December 31, 2018 2017 2016 Revenue Percent Revenue Percent Revenue Percent The Americas: United States of America $ 68,482 35 % $ 63,097 37 % $ 56,774 37 % Other 18,378 9 % 13,645 8 % 9,335 6 % Subtotal 86,860 44 % 76,742 45 % 66,109 43 % Germany 20,171 10 % 17,421 10 % 10,042 7 % The Rest of Europe 40,776 21 % 33,852 20 % 34,613 23 % Asia Pacific 32,090 16 % 26,528 16 % 30,457 20 % The Middle East 15,092 8 % 11,437 7 % 10,567 7 % Africa 2,035 1 % 2,836 2 % 1,488 1 % Total revenue $ 197,024 100 % $ 168,816 100 % $ 153,276 100 %

Concentrations of Risk

Concentrations of Risk	12 Months Ended
	Dec. 31, 2018
Risks and Uncertainties [Abstract]
Concentration Risk Disclosure [Text Block]	Concentrations of Credit Risk The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents, marketable securities and trade accounts receivable. The Company's deposits exceed federally insured limits. For the year ended December 31, 2018 , no customer accounted for 10% or more of trade accounts receivables. For the years ended December 31, 2018 , 2017 and 2016 , no single customer accounted for 10% or more of revenue.

Related Party Transaction

Related Party Transaction	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	Related-Party Transactions The Company currently has employment agreements with its executive officers. In the event of termination of employment other than for cause, the employment agreements provide separation benefits, including twelve to eighteen months of salary, as well as the vesting of certain equity awards.

Employment Retirement Savings

Employment Retirement Savings	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Defined Benefit Plan Disclosure [Line Items]	Employee Retirement Savings Plan The Company has a 401(k) savings plan for all eligible employees in the United States. Historically, the Company’s matching contribution has been 50% of the first 6% of employee contributions, and the Company may also make discretionary contributions. Matching contributions by the Company in 2018 , 2017 and 2016 totaled approximately $2.4 million , $2.0 million and $1.9 million , respectively.

Quarterly Results

Quarterly Results	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	Quarterly Results (Unaudited) The following table presents certain unaudited quarterly financial data for the years ended December 31, 2018 and 2017 . This information has been prepared on the same basis as the accompanying Consolidated Financial Statements and all necessary adjustments have been included in the amounts below to state fairly the selected quarterly information when read in conjunction with the accompanying Consolidated Financial Statements and Notes thereto. Quarter Ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 Total revenue $ 52,613 $ 49,075 $ 47,426 $ 47,910 Gross profit $ 33,155 $ 29,599 $ 28,702 $ 28,389 Loss from operations $ (9,609 ) $ (11,866 ) $ (12,993 ) $ (14,747 ) Net loss attributable to PROS Holdings, Inc. $ (12,760 ) $ (15,786 ) $ (16,844 ) $ (18,856 ) Net loss attributable to common stockholders per share: Basic $ (0.34 ) $ (0.44 ) $ (0.52 ) $ (0.58 ) Diluted $ (0.34 ) $ (0.44 ) $ (0.52 ) $ (0.58 ) Quarter Ended December 31, September 30, June 30, March 31, Total revenue $ 46,344 $ 41,937 $ 40,406 $ 40,129 Gross profit $ 28,197 $ 24,213 $ 24,320 $ 23,520 Loss from operations $ (12,815 ) $ (17,750 ) $ (16,710 ) $ (17,668 ) Net loss attributable to PROS Holdings, Inc. $ (16,980 ) $ (21,226 ) $ (19,513 ) $ (20,207 ) Net loss attributable to common stockholders per share: Basic $ (0.53 ) $ (0.67 ) $ (0.62 ) $ (0.65 ) Diluted $ (0.53 ) $ (0.67 ) $ (0.62 ) $ (0.65 )

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
Valuation and Qualifying Accounts [Abstract]
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Schedule II Valuation and Qualifying Accounts Balance at beginning of period Additions charged to costs and expenses Deductions (1) Other (2) Balance at end of period Allowance for doubtful accounts 2018 $ 760 $ 223 $ — $ (5 ) $ 978 2017 $ 760 $ — $ — $ — $ 760 2016 $ 586 $ 887 $ (713 ) $ — $ 760 Valuation allowance 2018 $ 74,153 $ 20,417 $ — $ (339 ) $ 94,231 2017 $ 69,049 $ 5,872 $ — $ (768 ) $ 74,153 2016 $ 44,321 $ 26,634 $ — $ (1,906 ) $ 69,049 (1) Deductions column represents the reversal of additions previously charged to costs and expenses and uncollectible accounts written off, net of recoveries. (2) Other column represents the cumulative translation adjustment impact on the allowance.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	Principles of Consolidation and Basis of Presentation These Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany transactions and balances have been eliminated in consolidation. The Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles in the United States of America ("GAAP").
Accounting Changes [Text Block]	Changes in Accounting Policies The Company has consistently applied the accounting policies described in this Note 2 to all periods presented in these Consolidated Financial Statements, except for the Company's adoption of certain accounting standards described in more detail under " Recently adopted accounting pronouncements " in this Note 2 below.
Dollar amounts	Dollar Amounts The dollar amounts presented in the tabular data within these footnote disclosures are stated in thousands of dollars, except per share amounts, or as noted within the context of each footnote disclosure.
Use of estimates	Use of Estimates The preparation of these Consolidated Financial Statements in conformity with GAAP requires the Company to make certain estimates, judgments and assumptions that affect the reported amounts of assets, liabilities, revenues, costs and expenses during the reporting period. These estimates include, but are not limited to, unbilled receivables and deferred revenue, the determination of the period of benefit for deferred commissions, receivables, allowance for doubtful accounts, useful lives of assets, depreciation and amortization, the fair value of assets acquired and liabilities assumed for business combinations, income taxes and deferred tax asset valuation, valuation of stock options, other current liabilities and accrued liabilities. Actual results could differ from those estimates and such differences could be material to the Company's consolidated financial position and results of operations.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase, or the ability to be settled in cash within a period of three months, to be cash equivalents, except for commercial paper which is classified as short-term investments, if any. The Company has a cash management program that provides for the investment of excess cash balances, primarily in short-term money market instruments.
Trade and Other Accounts Receivable, Unbilled Receivables, Policy [Policy Text Block]	Trade and Other Receivables Trade and other receivables are primarily comprised of trade receivables, net of allowance for doubtful accounts, contract assets and unbilled receivables. The Company's standard billing terms require payment within thirty to sixty days from the date of invoice. The carrying value of such receivables, net of the allowance for doubtful accounts, represents their estimated net realizable value. The Company estimates its allowance for doubtful accounts for specific trade receivable balances based on historical collection trends, the age of outstanding trade receivables, existing economic conditions, and any financial security associated with the receivables. Contract assets represent conditional rights to consideration that have been recognized as revenue in advance of billing the customer. Unbilled receivables represent unconditional rights to consideration arising from contingent revenue, that have been recognized as revenue in advance of billing the customer.
Equity Investments, Policy [Policy Text Block]	Equity Investments Investments in equity securities of privately held companies without readily determinable fair value, where the Company does not exercise significant influence over the investee, are recorded at cost, less impairment and adjusted for subsequent observable price changes obtained from orderly transactions for identical or similar investments issued by the same investee. Adjustments resulting from impairment, fair value, or observable price changes are accounted for in the Consolidated Statements of Comprehensive Income (Loss).
Fair Value of Financial Instruments, Policy [Policy Text Block]	Financial Instruments The carrying amount of the Company’s financial instruments, which include cash equivalents, receivables and accounts payable, and cost method investment approximates their fair values at December 31, 2018 and 2017 . For additional information on the Company’s fair value measurements, see Note 9 to the Consolidated Financial Statements.
Prepaid Expenses and Other Assets [Policy Text Block]	Prepaid Expenses and Other Assets Prepaid expenses and other assets consist primarily of prepaid third-party cloud infrastructure costs and license fees, deferred project costs and prepaid income taxes.
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment, Net Property and equipment are recorded at cost, less accumulated depreciation. Maintenance, repairs and minor replacements are charged to expense as incurred. Significant renewals and betterments are capitalized. Depreciation on property and equipment, with the exception of leasehold improvements, is recorded using the straight-line method over the estimated useful lives of the assets. Depreciation on leasehold improvements is recorded using the shorter of the lease term or useful life. When property is retired or disposed of, the cost and related accumulated depreciation are removed from the accounts and any resulting gains or losses are reflected in the Consolidated Statements of Comprehensive Income (Loss) in the period of disposal.
Internal-use software	Internal-Use Software Costs incurred to develop internal-use software during the application development stage are capitalized, stated at cost, and depreciated using the straight-line method over the estimated useful lives of the assets. Application development stage costs generally include salaries and personnel costs and third-party contractor expenses associated with internal-use software development, configuration and coding. Capitalization of such costs begins when the preliminary project stage is complete and ceases at the point in which the project is substantially complete and is ready for its intended purpose. Capitalized internal-use software is included in property and equipment, net in the Consolidated Balance Sheets.
Revenue Recognition, Customer Acquisitions [Policy Text Block]	Deferred Costs Sales commissions earned by the Company's sales representatives are considered incremental and recoverable costs of obtaining a customer contract. Sales commissions are deferred and amortized on a straight-line basis over the period of benefit, which the Company has determined to be five to eight years. The Company determined the period of benefit by taking into consideration its customer contracts, expected renewals of those customer contracts (as the Company currently does not pay an incremental sales commission), the Company's technology and other factors. The Company also defers amounts earned by employees other than sales representatives who earn incentive payments under compensation plans that are also tied to the value of customer contracts acquired.
Deferred Charges, Policy [Policy Text Block]	Deferred Implementation Costs The Company capitalizes certain contract fulfillment costs, including personnel and other costs (such as hosting, employee salaries, benefits and payroll taxes), that are associated with arrangements where professional services are not distinct from other undelivered obligations in its customer contracts. The Company analyzes implementation costs and capitalizes those costs that are directly related to customer contracts, that are expected to be recoverable, and that enhance the resources which will be used to satisfy the undelivered performance obligations in those contracts. Deferred implementation costs are amortized ratably over the remaining contract term once the revenue recognition criteria for the respective performance obligation has been met and revenue recognition commences. Deferred implementation costs are included in prepaid and other current assets and other assets, noncurrent in the Consolidated Balance Sheets. Amortization of deferred implementation costs is included in cost of subscription and cost of services revenues in the Consolidated Statements of Comprehensive Income (Loss).
Revenue Recognition, Deferred Revenue [Policy Text Block]	Deferred Revenue Deferred revenue primarily consists of customer invoicing in advance of revenues being recognized. The Company generally invoices its customers annually in advance for subscription services and maintenance and support services. Deferred revenue that is anticipated to be recognized during the next twelve-month period is recorded as current deferred revenue and the remaining portion is recorded as noncurrent deferred revenue.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever an event or change in circumstances indicates that the carrying amount of an asset or group of assets may not be recoverable. The impairment review includes comparison of future cash flows expected to be generated by the asset or group of assets with the associated assets’ carrying value. If the carrying value of the asset or group of assets exceeds its expected future cash flows (undiscounted and without interest charges), an impairment loss is recognized to the extent that the carrying amount of the asset exceeds its fair value. The Company recorded no impairment charges in the year ended December 31, 2018 , 2017 and 2016 .
Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block]	Intangible Assets and Goodwill Intangible assets that have finite lives are amortized over their useful lives and are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. During this review, the Company reevaluates the significant assumptions used in determining the original cost and estimated lives of long-lived assets. Although the assumptions may vary from asset to asset, they generally include operating results, changes in the use of the asset, cash flows and other indicators of value. Management then determines whether the remaining useful life continues to be appropriate or whether there has been an impairment of long-lived assets based primarily upon whether expected future undiscounted cash flows are sufficient to support the assets’ recovery. If impairment exists, the Company would adjust the carrying value of the asset to fair value, generally determined by a discounted cash flow analysis. Goodwill represents the excess of the purchase consideration over the net of the acquisition-date fair value of identifiable assets acquired, including identifiable intangible assets, and liabilities assumed in connection with business combinations. Goodwill is not amortized, but is assessed for impairment as of November 30 of each fiscal year, or more frequently if events or changes in circumstances indicate that the fair value of the Company’s sole reporting unit has been reduced below its carrying value. When conducting the annual goodwill impairment assessment, a three step process is used. The first step is to perform an optional qualitative evaluation as to whether it is more likely than not that the fair value of the Company’s sole reporting unit is less than its carrying value, using an assessment of relevant events and circumstances. In performing this assessment, the Company is required to make assumptions and judgments including but not limited to an evaluation of macroeconomic conditions as they relate to the business, industry and market trends, as well as the overall future financial performance of the reporting unit and future opportunities in the markets in which it operates. If it is determined that it is not more likely than not that the fair value of the reporting unit is less than its carrying value, no additional tests are required to be performed in assessing goodwill for impairment. However, if the Company concludes otherwise or elects not to perform the qualitative assessment, the Company performs a second step, consisting of a quantitative assessment of goodwill impairment. This quantitative assessment requires us to estimate the fair value of the reporting unit and compare the estimated fair value to its respective carrying value (including goodwill) as of the date of the impairment test. The third step, employed for the reporting unit failing the second step, is used to measure the amount of any potential impairment and compares the implied fair value of the reporting unit with the carrying amount of goodwill. Based on the results of the qualitative review of goodwill performed as of November 30, 2018, the Company did not identify any indicators of impairment. As such, the second and third steps described above were not necessary.
Research, Development, and Computer Software, Policy [Policy Text Block]	Research and Development Research and development costs for software sold to customers are expensed as incurred. These costs include salaries and personnel costs, including employee benefits, third-party contractor expenses, software development tools, an allocation of facilities and depreciation expenses and other expenses in developing new solutions and upgrading and enhancing existing solutions. Software Development Costs Capitalization of software development costs for software to be sold, leased, or otherwise marketed begins upon the establishment of technological feasibility, which is generally the completion of a working prototype that has been certified as having no critical bugs and is a release candidate. Amortization begins once the software is ready for its intended use, generally based on the pattern in which the economic benefits will be consumed. To date, software development costs incurred between completion of a working prototype and general availability of the related product have not been material.
Treasury Stock [Text Block]	Treasury Stock The Company is authorized to make treasury stock purchases in the open market pursuant to the share repurchase program, which was approved by its Board of Directors on August 28, 2008. The Company accounts for the purchase of treasury stock under the cost method. For additional information on the Company’s stock repurchase program, see Note 11 to the Consolidated Financial Statements. There were no treasury stock repurchases for the years ended December 31, 2018 , 2017 and 2016 .
Revenue recognition	Revenue Recognition The Company derives its revenues primarily from subscription services, professional services, perpetual licensing of its software products and associated software maintenance and support services. The Company determines revenue recognition through the following steps: • Identification of the contract, or contracts, with a customer; • Identification of the performance obligations in the customer contract(s); • Determination of the transaction price; • Allocation of the transaction price to each performance obligation in the customer contract(s); and • Recognition of revenue when, or as, the Company satisfies a performance obligation. Subscription services revenue Subscription services primarily include customer access to one or more of the Company's cloud applications and associated customer support. Subscription services revenue is generally recognized ratably over the contractual subscription term, beginning on the date that the Company's subscription service is made available to the customer. The Company's subscription contracts do not provide customers with the right to take possession of the software supporting the service and, as a result, are accounted for as service contracts. The Company's subscription contracts are generally two to five years in length, billed annually in advance, and non-cancelable. Maintenance and support revenue Maintenance and support revenue includes post-implementation customer support for on-premise licenses and the right to unspecified software updates and enhancements. The Company recognizes revenue from maintenance and support arrangements ratably over the period in which the services are provided. The Company's maintenance and support contracts are generally one to three years in length, billed annually in advance, and non-cancelable. License revenue Licenses to on-premise software provide the customer with a right to use, in the customer's environment, the Company's software as it exists when made available to the customer. License revenue from customer contracts with distinct on-premises licenses is recognized at the point in time when the software is made available to the customer. For customer contracts that contain license and professional services that are not considered distinct, both the license and professional services are determined to be a single performance obligation and the revenue is recognized over time based upon the Company's efforts to satisfy the performance obligation. Professional services revenue Professional services revenue primarily consists of fees for deployment and configuration services, as well as training services. Professional services revenues are generally recognized as the services are rendered for time and material contracts, or on a proportional performance basis for fixed fee contracts. The majority of the Company's professional services contracts are on a fixed fee basis. Training revenues are recognized as the services are rendered. Significant judgment is required in determining whether professional services contained in a customer subscription services contract are capable of being distinct and are separately identifiable in the customer contract. Professional services determined to be distinct are accounted for as a separate performance obligation and revenue is recognized as the services are performed. If the professional services are not determined to be distinct, the professional services and the subscription services are accounted for as a single performance obligation and revenue is recognized over the contractual term of the subscription beginning on the date that subscription services are made available to the customer. Customer contracts with multiple performance obligations A portion of the Company's customer contracts contain multiple performance obligations. Significant judgment is required in determining whether multiple performance obligations contained in a single customer contract are capable of being distinct and are separately identifiable. An obligation determined to be distinct is accounted for as a separate performance obligation and revenue for that separate performance obligation is recognized when, or as, the Company satisfies the performance obligation. If obligations are not determined to be distinct, those obligations are accounted for as a single, combined performance obligation. The transaction price is allocated to each performance obligation on a relative standalone selling price basis. Disaggregation of revenue The Company categorizes revenue from external customers by geographic area based on the location of the customer's headquarters. For additional information regarding the Company's revenue by geography, see Note 18 to the Consolidated Financial Statements.
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign Currency The Company has contracts denominated in foreign currencies and therefore a portion of the Company’s revenue is subject to foreign currency risks. Gains and losses from foreign currency transactions, such as those resulting from the settlement of receivables, are classified in other income (expense), net included in the accompanying Consolidated Statements of Comprehensive Income (Loss). The functional currency of PROS France SAS ("PROS France") is the Euro. The financial statements of this subsidiary are translated into U.S. dollars using period-end rates of exchange for assets and liabilities, historical rates of exchange for equity, and average rates of exchange for the period for revenue and expenses. Translation gains (losses) are recorded in accumulated other comprehensive income (loss) as a component of stockholders’ equity.
Noncash share-based compensation	Noncash Share-Based Compensation The Company has two noncash share-based compensation plans, the 2007 Equity Incentive Plan ("2007 Stock Plan") and the 2017 Equity Incentive Plan ("2017 Stock Plan"), which authorize the discretionary granting of various types of stock awards to key employees, officers, directors and consultants. The 2007 Stock Plan expired in March 2017. The 2017 Stock Plan serves as the successor to the 2007 Stock Plan and was adopted in May 2017. The Company may provide noncash share-based compensation through the grant of: (i) restricted stock awards; (ii) restricted stock unit awards - time and market-based ("RSUs"); (iii) stock options; (iv) stock appreciation rights ("SARs"); (v) phantom stock; and (vi) performance awards, such as market stock units ("MSUs"). To date, the Company has granted stock options, SARs, RSUs, time-based and market-based, and MSUs. The Company issues common stock from its pool of authorized stock upon exercise of stock options, settlement of SARs and MSUs or upon vesting of RSUs. The following table presents the number of awards outstanding for each award type as of December 31, 2018 and 2017 (in thousands): Year Ended December 31, Award type 2018 2017 Stock options — 135 Restricted stock units (time-based) 1,969 2,133 Restricted stock units (market-based) 215 345 Stock appreciation rights 287 356 Market stock units 419 387 Stock options. The Company did not grant stock options during 2018 and 2017 . The fair value of each stock option was estimated on the date of grant using the Black-Scholes option pricing model. Restricted stock units. The fair value of the RSUs (time-based and performance-based) is based on the closing price of the Company’s stock on the date of grant and is amortized over the vesting period. RSUs include (i) time-based awards, and (ii) market-based awards in which the number of shares that vest are based upon attainment of target average per share closing price over a requisite trading period. Market-based RSUs vest if the average trailing closing price of the Company's common stock meets certain minimum performance hurdles for at least 105 calendar days prior to September 9, 2020, with 25% vesting at $27 , an additional 25% vesting at $33 , and the remaining 50% vesting at $41 . The Company estimates the fair value and the derived service period of the market-based RSUs on the date of grant using a Monte Carlo simulation model. The model requires the use of a number of assumptions including the expected volatility of the Company's stock, its risk-free interest rate and expected dividends. The Company's expected volatility at the date of grant is based on the historical volatility of the Company over the performance period. Stock appreciation rights. SARs will be settled in stock at the time of exercise and vest over four years from the date of grant. The Company used the Black-Scholes option pricing model to estimate the fair value of its SARs. The determination of the fair value of SARs utilizing the Black-Scholes model is affected by the Company’s stock price and a number of assumptions, including expected volatility, expected life, delivery of risk-free interest rate and expected dividends. The Company estimates the expected volatility of common stock at the date of grant based on a combination of its historical volatility and the average volatility of comparable companies. The expected life of the SARs noncash share-based payment awards is a historical weighted average of the expected lives of similar securities of comparable public companies. The risk-free interest rate assumption is based on observed interest rates appropriate for the terms of the Company’s awards. The dividend yield assumption is based on the Company's expectation of paying no dividends. Market stock units. MSUs are performance-based awards that vest based upon the Company’s relative shareholder return. The actual number of MSUs that will be eligible to vest is based on the total shareholder return of the Company relative to the total shareholder return of the Russell 2000 Index ("Index") over a three year period ending December 31, 2017, March 2, 2018, February 28, 2019, February 28, 2020, October 9, 2020 and December 31, 2020 ("Performance Period"), respectively. The MSUs vested on January 1, 2018 and March 3, 2018, and will vest on March 1, 2019, March 1, 2020, October 9, 2020 and January 10, 2021, respectively. The maximum number of shares issuable upon vesting is 200% of the MSUs initially granted based on the average price of the Company's common stock relative to the Index during the Performance Period. The Company estimates the fair value of MSUs on the date of grant using a Monte Carlo simulation model. The determination of fair value of the MSUs is affected by the Company’s stock price and a number of assumptions including the expected volatility of the Company’s stock and the Index, its risk-free interest rate and expected dividends. The Company’s expected volatility at the date of grant was based on the historical volatilities of the Company and the Index over the Performance Period. As the Company issues stock options and SARs, it evaluates the assumptions used to value its stock option awards and SARs. If factors change and the Company employs different assumptions, noncash share-based compensation expense may differ significantly from what has been recorded in the past. If there are any modifications or cancellations of the underlying unvested securities, the Company may be required to accelerate, increase or cancel any remaining unearned noncash share-based compensation expense. Future noncash share-based compensation expense and unearned noncash share-based compensation will increase to the extent that the Company grants additional equity awards to employees. At December 31, 2018 , there were an estimated $33.3 million of total unrecognized compensation costs related to noncash share-based compensation arrangements. These costs will be recognized over a weighted average period of 2.4 years. For further discussion of the Company’s noncash share-based compensation plans, see Note 13 to the Consolidated Financial Statements.
Standard Product Warranty, Policy [Policy Text Block]	Product Warranties For software-as-a-service application subscriptions, the Company generally issues a product warranty for the subscription term, depending on the contract. For on-premise software licenses, the Company generally issues a product warranty for 90 days following the first use of the software in a production environment, depending on the contract. In the Company’s experience, warranty costs have been insignificant.
Income taxes	Income Taxes The Company uses the asset and liability method to account for income taxes, including recognition of deferred tax assets and liabilities for the anticipated future tax consequences attributable to differences between financial statement amounts and their respective tax basis. The Company reviews its deferred tax assets for recovery. A valuation allowance is established when the Company believes that it is more-likely than not that some portion of its deferred tax assets will not be realized. Changes in the valuation allowance from period to period are included in the Company’s tax provision in the period of change. The Company accounts for uncertain income tax positions recognized in an enterprise’s financial statements in accordance with the income tax topic of the ASC issued by the FASB. This interpretation requires companies to use a prescribed model for assessing the financial recognition and measurement of all tax positions taken or expected to be taken in its tax returns. This guidance provides clarification on recognition, classification, interest and penalties, accounting in interim periods, disclosures and transition. The Company recognized accrued interest and penalties related to income taxes as a component of income tax expense. For additional information regarding the Company’s income taxes, see Note 14 to the Consolidated Financial Statements.
Segment Reporting, Policy [Policy Text Block]	Segment Reporting The Company reports as one operating segment with the Chief Executive Officer ("CEO") acting as the Company’s chief operating decision maker. The Company’s CEO reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company has a single reporting unit, and there are no segment managers who are held accountable for operations, operating results or components below the consolidated unit level.
Earnings per share	Earnings Per Share The Company computes basic earnings (loss) per share by dividing net income (loss) attributable to common stockholders by the weighted average number of common shares outstanding. Diluted earnings (loss) per share is computed by dividing net income (loss) attributable to common stockholders by the weighted average number of common shares and dilutive potential common shares then outstanding. Diluted earnings per share reflect the assumed conversion of all dilutive securities, using the treasury stock method. Dilutive potential common shares consist of shares issuable upon the exercise of stock options, shares of unvested RSUs, and settlement of SARs. When the Company incurs a net loss, the effect of the Company’s outstanding stock options, SARs, RSUs and MSUs are not included in the calculation of diluted earnings (loss) per share as the effect would be anti-dilutive. Accordingly, basic and diluted net loss per share are identical.
Recent accounting pronouncements	Recently Adopted Accounting Pronouncements Topic 606 In May 2014, the FASB issued Accounting Standards Update ("ASU") No. 2014-09, " Revenue from Contracts with Customers (Topic 606) " ("Topic 606"). Topic 606 replaces the prior revenue recognition requirements in ASC 605, "Revenue Recognition" ("Topic 605" or "Prior Guidance") with a comprehensive revenue measurement and recognition standard, and expanded disclosure requirements. The new standard also provides guidance on the recognition of costs related to obtaining customer contracts. Topic 606 took effect in the first quarter of 2018, including interim periods within that reporting period. The Company adopted Topic 606 and applied Topic 606 to those contracts which were not complete as of January 1, 2018 using the modified retrospective method by recognizing the cumulative effect of initially applying the new standard as an adjustment to the opening balance of accumulated deficit, while prior period amounts are not adjusted and continue to be reported in accordance with the Company's historic accounting under the Prior Guidance. The most significant impact of Topic 606 relates to the Company's accounting for arrangements that include term-based software licenses bundled with maintenance and support, the deferral of incremental costs of obtaining a contract with a customer (including the period of amortization of such costs), and additional disclosures. Under the Prior Guidance, revenue attributable to term-based software licenses was recognized ratably over the term of the arrangement when vendor-specific objective evidence ("VSOE") did not exist for the undelivered maintenance and support element because it was not sold separately. Topic 606 does not require VSOE for undelivered elements to separate revenue for the delivered software licenses. Accordingly, under the new standard, the Company is required to recognize as revenue a portion of the arrangement fee upon delivery of the software license. As a result of applying Topic 606, the adjustment to the Company's opening balance sheet of the accumulated deficit for all revenue-related items was a decrease of approximately $2.7 million . Topic 606 also requires the Company to capitalize and amortize the costs to obtain a contract over the expected period of customer benefit. The Company previously capitalized and amortized only direct and incremental commission costs over the term of the related contract. The expected period of customer benefit determined under Topic 606 is longer than the typical two to five year term of the Company's contracts as required under the Prior Guidance. As a result of applying Topic 606, the Company recorded a decrease to the opening balance sheet of the accumulated deficit for costs to obtain a contract of approximately $7.0 million . Impact to previous reported results The Company applied Topic 606 using the modified retrospective method by recognizing the cumulative effect of initially applying Topic 606 as an adjustment to the opening balance sheet at January 1, 2018. Therefore, the comparative information has not been adjusted and continues to be reported under Topic 605. The differences between amounts reported under Topic 606 and what would have been reported Topic 605 are detailed below: December 31, 2018 (in thousands) As Reported Adjustments Balances Under Topic 605 Balance Sheets Trade and other receivables, net of allowance $ 41,822 $ (232 ) $ 41,590 Deferred costs, current 4,089 (30 ) 4,059 Deferred costs, noncurrent 13,373 (8,278 ) 5,095 Deferred revenue, current 99,262 2,120 101,382 Deferred revenue, noncurrent 17,903 1,088 18,991 Accumulated deficit $ (292,708 ) $ (11,748 ) $ (304,456 ) Year Ended December 31, 2018 (in thousands, except per share amounts) As Reported Adjustments Balances Under Topic 605 Income Statements Total revenue $ 197,024 $ (761 ) $ 196,263 Total cost of revenue 77,179 369 77,548 Selling and marketing 72,006 1,453 73,459 General and administrative 41,302 (318 ) 40,984 Research and development 55,657 (234 ) 55,423 Net loss (64,246 ) (2,031 ) (66,277 ) Basic and diluted loss per share $ (1.86 ) $ (0.06 ) $ (1.92 ) Topic 230 In August 2016, the FASB issued ASU 2016-15, " Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments " which is intended to reduce the diversity in practice on classification of certain transactions in the statement of cash flows. The Company adopted this standard on January 1, 2018 and the adoption had no impact on its Consolidated Financial Statements and related disclosures. In November 2016, the FASB issued ASU 2016-18, " Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force " which is intended to define the presentation and related disclosures of restricted cash balances. The Company adopted this standard on January 1, 2018 and the adoption had no impact on its Consolidated Financial Statements and related disclosures. Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, " Leases (Topic 842) " ("Topic 842"), which requires the lessee to recognize most leases on the balance sheet thereby resulting in the recognition of right-of-use ("ROU") lease assets and liabilities for those leases currently classified as operating leases. Lessor accounting remains largely unchanged from current guidance, however, Topic 842 provides improvements that are intended to align lessor accounting with the lessee model and with updated revenue recognition guidance. This standard is effective for interim and annual reporting periods beginning after December 15, 2018. The Company plans to adopt the standard as of January 1, 2019. The Company will elect the package of practical expedients permitted under the transition guidance within the new Topic 842 standard, which among other things, allows the Company to carryforward the historical lease classification. The Company will also elect the hindsight practical expedient to determine the reasonably certain lease term for existing leases. The Company will make an accounting policy election to keep leases with an initial term of 12 months or less off of the balance sheet and will recognize those lease payments on a straight-line basis over the lease term. The adoption of the standard will have a material impact on the Company’s Consolidated Balance Sheet as a result of the increase in assets and liabilities from recognition of ROU assets and lease liabilities. The Company does not believe the standard will have a material impact on the its Consolidated Statement of Comprehensive Income (Loss). In January 2017, the FASB issued ASU 2017-04, " Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment " ("Topic 350"), which eliminates step two from the goodwill impairment test. Under the amendments in this standard, an entity should recognize an impairment charge for the amount by which the carrying amount of a reporting unit exceeds its fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The standard is effective for interim and annual reporting periods beginning after December 15, 2019; earlier adoption is permitted for goodwill impairment tests performed on testing dates after January 1, 2017. The Company is currently assessing the impact of Topic 350 on its Consolidated Financial Statements. With the exception of the new standards discussed above, there have been no other recent accounting pronouncements or changes in accounting pronouncements during the year ended December 31, 2018 , that are of significance or potential significance to the Company.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]	The following table presents the number of awards outstanding for each award type as of December 31, 2018 and 2017 (in thousands): Year Ended December 31, Award type 2018 2017 Stock options — 135 Restricted stock units (time-based) 1,969 2,133 Restricted stock units (market-based) 215 345 Stock appreciation rights 287 356 Market stock units 419 387
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	The Company applied Topic 606 using the modified retrospective method by recognizing the cumulative effect of initially applying Topic 606 as an adjustment to the opening balance sheet at January 1, 2018. Therefore, the comparative information has not been adjusted and continues to be reported under Topic 605. The differences between amounts reported under Topic 606 and what would have been reported Topic 605 are detailed below: December 31, 2018 (in thousands) As Reported Adjustments Balances Under Topic 605 Balance Sheets Trade and other receivables, net of allowance $ 41,822 $ (232 ) $ 41,590 Deferred costs, current 4,089 (30 ) 4,059 Deferred costs, noncurrent 13,373 (8,278 ) 5,095 Deferred revenue, current 99,262 2,120 101,382 Deferred revenue, noncurrent 17,903 1,088 18,991 Accumulated deficit $ (292,708 ) $ (11,748 ) $ (304,456 ) Year Ended December 31, 2018 (in thousands, except per share amounts) As Reported Adjustments Balances Under Topic 605 Income Statements Total revenue $ 197,024 $ (761 ) $ 196,263 Total cost of revenue 77,179 369 77,548 Selling and marketing 72,006 1,453 73,459 General and administrative 41,302 (318 ) 40,984 Research and development 55,657 (234 ) 55,423 Net loss (64,246 ) (2,031 ) (66,277 ) Basic and diluted loss per share $ (1.86 ) $ (0.06 ) $ (1.92 )

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
	Dec. 31, 2018
Business Acquisition [Line Items]
Schedule of Purchase Price Allocation [Table Text Block]	The final allocation of the total purchase price for Vayant is as follows (in thousands): Cash $ 1,822 Other current assets 1,235 Noncurrent assets 86 Intangibles 18,600 Goodwill 17,052 Accounts payable and accrued liabilities (1,668 ) Deferred revenue (600 ) Deferred tax liability (526 ) Noncurrent liabilities (49 ) Net assets acquired $ 35,952
Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	The following are the identifiable intangible assets acquired (in thousands) and their respective useful lives: Useful Life Amount (years) Developed technology $ 11,600 7 Customer relationships 7,000 5 Total $ 18,600
Business Acquisition, Pro Forma Information [Table Text Block]	ro Forma Financial Information The unaudited financial information in the table below summarizes the combined results of operations of the Company and Vayant, on a pro forma basis, as though the Company had acquired Vayant on January 1, 2016. The pro forma information for all periods presented also includes the effect of business combination accounting resulting from the acquisition, including amortization charges from acquired intangible assets. Year Ended December 31, (in thousands, except earnings per share) 2017 2016 Total revenue $ 173,866 $ 160,696 Net loss (81,476 ) (81,652 ) Earnings per share - basic and diluted $ (2.58 ) $ (2.69 )

Trade and Other Receivables, _2

Trade and Other Receivables, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Accounts Receivable [Abstract]
Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block]	Accounts receivable at December 31, 2018 and 2017 , consists of the following (in thousands): December 31, 2018 2017 Accounts receivable $ 38,876 $ 30,689 Unbilled receivables and contract assets 3,924 2,555 Total receivables 42,800 33,244 Less: Allowance for doubtful accounts (978 ) (760 ) Trade and other receivables, net $ 41,822 $ 32,484

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	Property and equipment, net as of December 31, 2018 and 2017 consists of the following: December 31, Estimated useful life 2018 2017 Furniture and fixtures 5-10 years $ 3,208 $ 2,958 Computers and equipment 3-5 years 19,644 18,950 Software 3-6 years 5,432 5,430 Capitalized internal-use software development costs 3 years 8,775 4,102 Leasehold improvements Shorter of lease term or useful life 5,587 5,650 Construction in progress 20 19 Property and equipment, gross 42,666 37,109 Less: Accumulated depreciation and amortization (27,990 ) (23,102 ) Property and equipment, net $ 14,676 $ 14,007

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill [Line Items]
Schedule of Goodwill [Table Text Block]	The change in the carrying amount of goodwill for the years ended December 31, 2018 and 2017 , was as follows (in thousands): Balance as of December 31, 2016 $ 20,096 Goodwill acquired 17,052 Foreign currency translation adjustments 1,310 Balance as of December 31, 2017 38,458 Purchase accounting adjustments 252 Foreign currency translation adjustments (479 ) Balance as of December 31, 2018 $ 38,231
Schedule of Finite-Lived Intangible Assets [Table Text Block]	Intangible assets consisted of the following as of December 31, (in thousands): December 31, 2018 Weighted average useful life (years) Gross Carrying Amount Accumulated Amortization* Net Carrying Amount Developed technology 7 $ 25,584 $ 13,890 $ 11,694 Maintenance relationships 8 3,485 2,488 997 Customer relationships 6 11,802 6,884 4,918 Acquired technology 2 1,925 180 1,745 Total $ 42,796 $ 23,442 $ 19,354 *Cumulative foreign currency translation adjustments, reflecting movement in the currencies of the underlying entities, decreased total intangible assets by approximately $0.2 million as of December 31, 2018 . December 31, 2017 Weighted average useful life (years) Gross Carrying Amount Accumulated Amortization* Net Carrying Amount Developed technology 7 $ 26,023 $ 9,560 $ 16,463 Maintenance relationships 8 3,565 2,207 1,358 Customer relationships 6 11,840 4,482 7,358 Acquired technology 3 1,750 — 1,750 Total $ 43,178 $ 16,249 $ 26,929 *Cumulative foreign currency translation adjustments, reflecting movement in the currencies of the underlying entities, increased total intangible assets by approximately $0.7 million as of December 31, 2017 . Customer relationships are amortized over five or eight years.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	As of December 31, 2018 , the expected future amortization expense for the acquired intangible assets for each of the five succeeding years and thereafter was as follows (in thousands): Year Ending December 31, Amount 2019 $ 6,575 2020 5,791 2021 3,021 2022 1,921 2023 1,292 2024 and thereafter 754 Total amortization expense $ 19,354

Earnings per Share (Table)

Earnings per Share (Table)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the computation of basic and diluted earnings per share: For the Year Ended December 31, 2018 2017 2016 Numerator: Net loss $ (64,246 ) $ (77,926 ) $ (75,225 ) Denominator: Weighted average shares (basic) 34,465 31,627 30,395 Dilutive effect of stock options, restricted stock units and stock appreciation rights — — — Weighted average shares (diluted) 34,465 31,627 30,395 Basic earnings per share $ (1.86 ) $ (2.46 ) $ (2.47 ) Diluted earnings per share $ (1.86 ) $ (2.46 ) $ (2.47 )

Noncash Share-based Compensat_2

Noncash Share-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation Expense	Noncash share-based compensation expense is allocated to expense categories on the Consolidated Statements of Comprehensive Income (Loss). The following table summarizes noncash share-based compensation expense, net of amounts capitalized, for the years ended December 31, 2018 , 2017 and 2016 (in thousands). For the Year Ended December 31, 2018 2017 2016 Share-based compensation: Cost of revenue $ 1,721 $ 1,971 $ 2,267 Operating expenses: Selling and marketing 4,396 4,348 3,824 General and administrative 10,717 11,163 9,040 Research and development 4,619 5,314 5,335 Total included in operating expenses 19,732 20,825 18,199 Total share-based compensation expense $ 21,453 $ 22,796 $ 20,466
Share-based Compensation, Stock Options, Activity [Table Text Block]	The following table summarizes the Company’s stock option activity for the year ended December 31, 2018 (number of shares and intrinsic value in thousands): Number of shares under option Weighted average exercise price Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Outstanding, December 31, 2017 135 $ 12.52 Granted — — Exercised (135) 12.52 Forfeited — — Expired — — Outstanding, December 31, 2018 — $ — 0 $ — Vested and exercisable at December 31, 2018 — $ — 0 $ — (1) The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the grant date fair value.
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value [Table Text Block]	The following table summarizes the Company's SARs activity for the year ended December 31, 2018 (number of shares and intrinsic value in thousands): Stock appreciation rights Weighted average exercise price Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Outstanding, December 31, 2017 356 $ 10.97 Granted — — Exercised (69 ) 11.17 Forfeited — — Expired — — Outstanding, December 31, 2018 287 $ 10.92 1.86 $ 5,869 Exercisable at December 31, 2018 287 $ 10.92 1.86 $ 5,869 Vested and expected to vest at December 31, 2018 287 $ 10.92 1.86 $ 5,869 (1) The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the exercise price of the underlying SARs.
Schedule of Nonvested Performance-based Units Activity [Table Text Block]	The following table summarizes the Company's MSUs activity for the year ended December 31, 2018 (number of shares and intrinsic value in thousands): Number of unvested awards Weighted average grant date fair value Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Unvested at December 31, 2017 387 $ 23.48 Granted 117 38.18 Exercised (85 ) 31.83 Forfeited — — Expired — — Unvested at December 31, 2018 419 $ 25.90 1.10 $ 13,162 (1) The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the grant date fair value of the underlying MSUs.
Fair value assumptions - market-based RSUs [Table Text Block]	The assumptions used to value the market-based RSUs granted in 2016 were as follows: December 31, 2016 Volatility 44.98% Risk-free interest rate 1.08% Dividend yield — The fair value of the market-based RSUs is expensed over the derived service period for each separate vesting tranche. The derived service period for the vesting tranches of the market-based RSUs ranges between 1.01 and 1.98 years.
Market Stock Units Valuation Assumptions [Table Text Block]	Significant assumptions used in the Monte Carlo simulation model for MSUs granted during the years ended December 31, 2018 , 2017 and 2016 are as follows: For the Year Ended December 31, 2018 2017 2016 Volatility 43.67% 45.38% 44.06% Risk-free interest rate 2.12% 1.56% 1.04% Expected option life in years 2.97 3.07 2.93 Dividend yield — — — The assumptions related to fiscal year 2017 are presented on a weighted average basis for the various awards granted throughout the period.
Restricted Stock Unit - time based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]	The following table summarizes the Company's unvested time-based RSUs as of December 31, 2018 , and changes during the year then ended (number of shares and intrinsic value in thousands): Number of shares Weighted average grant date fair value Weighted average remaining contractual term (year) Aggregate intrinsic value (1) Unvested at December 31, 2017 2,133 $ 18.90 Granted 829 27.61 Vested (792 ) 20.49 Forfeited (201 ) 20.45 Unvested at December 31, 2018 1,969 $ 21.77 2.02 $ 61,827 Expected to vest at December 31, 2018 1,902 $ 21.65 2.00 $ 59,731 (1) The aggregate intrinsic value was calculated based on the fair value of the Company’s common stock on December 31, 2018 of $31.40 .
Restricted stock unit - market-based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]	The following table summarizes the Company's unvested market-based RSUs as of December 31, 2018 , and changes during the year then ended (number of shares and intrinsic value in thousands): Number of Weighted Weighted Aggregate Unvested at December 31, 2017 345 $ 10.86 Granted — — Vested (115 ) 12.61 Forfeited (15 ) 9.98 Unvested at December 31, 2018 215 $ 9.98 1.69 $ 6,751 Expected to vest at December 31, 2018 211 $ 9.98 1.69 $ 6,611 (1) The aggregate intrinsic value was calculated based on the fair value of the Company’s common stock on December 31, 2018 of $31.40 .

Income Tax Disclosure (Tables)

Income Tax Disclosure (Tables)	12 Months Ended
	Dec. 31, 2018
Schedule of income tax components [Abstract]
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The income tax provision consisted of the following for the years ended December 31, 2018 , 2017 and 2016 (in thousands): Year Ended December 31, 2018 2017 2016 Current: Federal $ (252 ) $ — $ 19 State and Foreign 663 669 402 411 669 421 Deferred: Federal (211 ) (488 ) 51 State — (32 ) (2 ) Income tax provision $ 200 $ 149 $ 470
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The differences between the effective tax rates reflected in the total provision for income taxes and the U.S. federal statutory rate of 34% for the years ended December 31, 2018 , 2017 and 2016 , respectively, were as follows (in thousands): Year Ended December 31, 2018 2017 2016 Provision at the U.S. federal statutory rate $ (13,464 ) $ (26,443 ) $ (25,338 ) Increase (decrease) resulting from: State income taxes, net of federal taxes 46 18 3 Nondeductible expenses 414 373 457 Acquisition-related expense — 245 (4 ) Statutory to GAAP income adjustment (221 ) (77 ) (274 ) Foreign Tax Expense — — 2 Noncash share-based compensation (394 ) (3,405 ) 604 Other (153 ) — 49 Incremental benefits for tax credits (1,656 ) (1,711 ) (1,663 ) Change in tax rate/income subject to lower tax rates (1,824 ) 2,625 — Change related to prior tax years (4,800 ) (2,331 ) (856 ) Change related to US tax reform 1,835 31,359 — Change in valuation allowance 20,417 (504 ) 27,490 Income tax provision $ 200 $ 149 $ 470
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	The tax effects of temporary differences and other tax attributes that give rise to significant portions of the deferred tax assets and liabilities as of December 31, 2018 and 2017 are as follows (in thousands): Year Ended December 31, 2018 2017 Noncurrent deferred taxes: Property and equipment $ (528 ) $ (847 ) Noncash share-based compensation 6,922 6,373 Disallowed interest expense 4,574 — Capitalized software (1,533 ) (1,397 ) Amortization (4,110 ) (5,096 ) R&E tax credit carryforwards 10,603 9,340 Deferred revenue 2,680 2,996 Federal Net Operating Losses ("NOLs") 58,601 46,907 State NOLs 2,319 1,050 State Credits 2,005 1,613 Foreign NOLs 8,945 9,057 Foreign tax credit carryforward 2,462 2,521 Other 1,291 1,425 Total noncurrent deferred tax assets 94,231 73,942 Less: Valuation allowance (94,231 ) (74,153 ) Total noncurrent deferred tax liability — (211 ) Total net deferred tax liability $ — $ (211 )
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	The following table sets forth the changes to the Company's unrecognized tax benefit for the year ended December 31, 2018 , 2017 and 2016 (in thousands): Year Ended December 31, 2018 2017 2016 Beginning balance $ 183 $ 192 $ 192 Changes based on tax positions related to prior year — — — Changes due to settlement — (9 ) — Ending balance $ 183 $ 183 $ 192 The table above has been updated to reflect gross tax liability, exclusive of interest and penalties and other offsetting amounts.

Convertible debt (Tables)

Convertible debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Instrument [Line Items]
Convertible Debt [Table Text Block]	The Notes consist of the following (in thousands): December 31, 2018 December 31, 2017 Liability component: Principal $ 250,000 $ 250,000 Less: debt discount, net of amortization (24,810 ) (36,797 ) Net carrying amount $ 225,190 $ 213,203 Equity component (1) $ 37,560 $ 37,560 (1) Recorded within additional paid-in capital in the Consolidated Balance Sheet. As of December 31, 2018 , it included $28.7 million and $8.8 million related to the 2019 Notes and the 2047 Notes, respectively, net of $1.2 million and $0.3 million issuance cost in equity, respectively. The following table sets forth total interest expense recognized related to the Notes (in thousands): Year Ended December 31, 2018 2017 2.0% coupon $ 5,000 $ 3,991 Amortization of debt issuance costs 1,419 1,127 Amortization of debt discount 10,567 8,100 Total $ 16,986 $ 13,218

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]	As of December 31, 2018 , the future minimum lease commitments related to lease agreements were as follows: Year Ending December 31, Amount 2019 $ 4,164 2020 1,649 2021 5,115 2022 6,181 2023 5,679 2024 and thereafter 57,365 Total minimum lease payments $ 80,153

Segment and Geographical Info_2

Segment and Geographical Information (Tables)	12 Months Ended
	Dec. 31, 2018
Schedule of Geographic Revenue [Abstract]
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]	The following geographic information is presented for the years ended December 31, 2018 , 2017 and 2016 . The Company categorizes geographic revenues based on the location of the customer’s headquarters. Year Ended December 31, 2018 2017 2016 Revenue Percent Revenue Percent Revenue Percent The Americas: United States of America $ 68,482 35 % $ 63,097 37 % $ 56,774 37 % Other 18,378 9 % 13,645 8 % 9,335 6 % Subtotal 86,860 44 % 76,742 45 % 66,109 43 % Germany 20,171 10 % 17,421 10 % 10,042 7 % The Rest of Europe 40,776 21 % 33,852 20 % 34,613 23 % Asia Pacific 32,090 16 % 26,528 16 % 30,457 20 % The Middle East 15,092 8 % 11,437 7 % 10,567 7 % Africa 2,035 1 % 2,836 2 % 1,488 1 % Total revenue $ 197,024 100 % $ 168,816 100 % $ 153,276 100 %

Quarterly Results Quarterly Fin

Quarterly Results Quarterly Financial Information Disclosures (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	The following table presents certain unaudited quarterly financial data for the years ended December 31, 2018 and 2017 . This information has been prepared on the same basis as the accompanying Consolidated Financial Statements and all necessary adjustments have been included in the amounts below to state fairly the selected quarterly information when read in conjunction with the accompanying Consolidated Financial Statements and Notes thereto. Quarter Ended December 31, 2018 September 30, 2018 June 30, 2018 March 31, 2018 Total revenue $ 52,613 $ 49,075 $ 47,426 $ 47,910 Gross profit $ 33,155 $ 29,599 $ 28,702 $ 28,389 Loss from operations $ (9,609 ) $ (11,866 ) $ (12,993 ) $ (14,747 ) Net loss attributable to PROS Holdings, Inc. $ (12,760 ) $ (15,786 ) $ (16,844 ) $ (18,856 ) Net loss attributable to common stockholders per share: Basic $ (0.34 ) $ (0.44 ) $ (0.52 ) $ (0.58 ) Diluted $ (0.34 ) $ (0.44 ) $ (0.52 ) $ (0.58 ) Quarter Ended December 31, September 30, June 30, March 31, Total revenue $ 46,344 $ 41,937 $ 40,406 $ 40,129 Gross profit $ 28,197 $ 24,213 $ 24,320 $ 23,520 Loss from operations $ (12,815 ) $ (17,750 ) $ (16,710 ) $ (17,668 ) Net loss attributable to PROS Holdings, Inc. $ (16,980 ) $ (21,226 ) $ (19,513 ) $ (20,207 ) Net loss attributable to common stockholders per share: Basic $ (0.53 ) $ (0.67 ) $ (0.62 ) $ (0.65 ) Diluted $ (0.53 ) $ (0.67 ) $ (0.62 ) $ (0.65 )

Summary of Significant Accoun_4

Summary of Significant Accounting Policies Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2018
Summary of Significant Accounting Policies [Line Items]
Tangible Asset Impairment Charges	$ 0
Total shareholder return period, in years, for vesting of MSUs	3 years
Shares issuable upon vesting of MSUs, maximum	200.00%
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 33,266
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	2 years 4 months 13 days
Share-based Compensation Award, Tranche One [Member]
Summary of Significant Accounting Policies [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards vesting upon Price Target	25.00%
Share Price Target	$ 27
Share-based Compensation Award, Tranche Two [Member]
Summary of Significant Accounting Policies [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards vesting upon Price Target	25.00%
Share Price Target	$ 33
Share-based Compensation Award, Tranche Three [Member]
Summary of Significant Accounting Policies [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards vesting upon Price Target	50.00%
Share Price Target	$ 41
Accounting Standards Update 2014-09 [Member]
Summary of Significant Accounting Policies [Line Items]
New Accounting Pronouncement, Cumulative Effect of Change on Equity, Impact of Revenue		$ 2,700
New Accounting Pronouncement, Cumulative Effect of Change on Equity, Impact of Cost to Obtain Contract		$ 7,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Awards Outstanding (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Stock options
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	0	135,000
Restricted Stock Unit - time based [Member]
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	1,969,000	2,133,000
Restricted stock unit - market-based [Member]
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	215,000	345,000
Stock Appreciation Rights (SARs) [Member]
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	287,000	356,000
MSUs
Awards outstanding [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	419,000	387,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Impact of adoption of a new pronouncement (Details) - USD ($) $ / shares in Units, $ 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
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Account and Unbilled Receivables, Net	$ 41,822				$ 32,484				$ 41,822	$ 32,484
Deferred Costs, Current	4,089				3,137				4,089	3,137
Deferred Costs, Noncurrent	13,373				3,194				13,373	3,194
Deferred Revenue, Current	99,262				75,604				99,262	75,604
Deferred Revenue, Noncurrent	17,903				19,591				17,903	19,591
Retained Earnings (Accumulated Deficit)	(292,708)				(238,185)				(292,708)	(238,185)
Revenues	52,613	$ 49,075	$ 47,426	$ 47,910	46,344	$ 41,937	$ 40,406	$ 40,129	197,024	168,816	$ 153,276
Cost of Revenue									77,179	68,566	63,353
Selling and Marketing Expense									72,006	68,116	63,980
General and Administrative Expense									41,302	40,336	38,537
Research and development									55,657	56,021	52,804
Net Income (Loss) Attributable to Parent	(12,760)	$ (15,786)	$ (16,844)	$ (18,856)	$ (16,980)	$ (21,226)	$ (19,513)	$ (20,207)	$ (64,246)	$ (77,926)	$ (75,225)
Earnings Per Share, Basic and Diluted									$ (1.86)	$ (2.46)	$ (2.47)
Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Account and Unbilled Receivables, Net	41,590								$ 41,590
Deferred Costs, Current	4,059								4,059
Deferred Costs, Noncurrent	5,095								5,095
Deferred Revenue, Current	101,382								101,382
Deferred Revenue, Noncurrent	18,991								18,991
Retained Earnings (Accumulated Deficit)	(304,456)								(304,456)
Revenues									196,263
Cost of Revenue									77,548
Selling and Marketing Expense									73,459
General and Administrative Expense									40,984
Research and development									55,423
Net Income (Loss) Attributable to Parent									$ (66,277)
Earnings Per Share, Basic and Diluted									$ (1.92)
Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Account and Unbilled Receivables, Net	(232)								$ (232)
Deferred Costs, Current	(30)								(30)
Deferred Costs, Noncurrent	(8,278)								(8,278)
Deferred Revenue, Current	2,120								2,120
Deferred Revenue, Noncurrent	1,088								1,088
Retained Earnings (Accumulated Deficit)	$ (11,748)								(11,748)
Revenues									(761)
Cost of Revenue									369
Selling and Marketing Expense									1,453
General and Administrative Expense									(318)
Research and development									(234)
Net Income (Loss) Attributable to Parent									$ (2,031)
Earnings Per Share, Basic and Diluted									$ (0.06)

Business Combination (Details)

Business Combination (Details) - USD ($)	Aug. 03, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
Payments to Acquire Businesses, Net of Cash Acquired	$ 34,100,000	$ 0	$ 34,130,000	$ 0
Business Combination, Acquisition Related Costs		95,000	720,000	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	18,600,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue	600,000
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual		9,500,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual		(4,800,000)
Goodwill, Acquired During Period			17,052,000
Goodwill	17,052,000	38,231,000	$ 38,458,000	$ 20,096,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount		0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	$ 526,000	778,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustments Related to Previous Period		$ (252,000)

Business Combination Assets Acq

Business Combination Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Aug. 03, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents			$ 1,822
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other			1,235
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Other Noncurrent Assets			86
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			18,600
Goodwill	$ 38,231	$ 38,458	17,052	$ 20,096
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other			(1,668)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue			(600)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent	$ (778)		(526)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other			(49)
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net			$ 35,952

Business Combination Schedule o

Business Combination Schedule of Intangible Assets Acquired (Details) - USD ($) $ in Thousands	Aug. 03, 2017	Dec. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Business Acquisition, Purchase Price Allocation, Amortizable Intangible Assets	$ 18,600
Customer Relationships [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 7,000
Finite-Lived Intangible Asset, Useful Life		6 years	6 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 years
Maintenance relationship [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life		8 years	8 years
Developed Technology Rights [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived Intangible Assets Acquired	$ 11,600
Finite-Lived Intangible Asset, Useful Life		7 years	7 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years

Business Combination Pro Forma

Business Combination Pro Forma (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue	$ 173,866	$ 160,696
Business Acquisition, Pro Forma Net Income (Loss)	$ (81,476)	$ (81,652)
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ (2.58)	$ (2.69)

Trade and Other Receivables, _3

Trade and Other Receivables, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross	$ 38,876	$ 30,689
Unbilled Receivables, Current	3,924	2,555
Accounts Receivable, Net, Current	42,800	33,244
Allowance for Doubtful Accounts Receivable	(978)	(760)
Account and Unbilled Receivables, Net	41,822	32,484
Bad debt expense	$ 223	$ 0	$ 223

Deferred Costs (Details)

Deferred Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs [Abstract]
Deferred Costs	$ 17.5	$ 6.3
Amortization of Deferred Charges	$ 3	$ 2.5

Deferred Implementation costs_2

Deferred Implementation costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Deferred Implementation Costs [Abstract]
Capitalized Contract Cost, Net	$ 3.9	$ 2.2
Capitalized Contract Cost, Amortization	$ 0.6	$ 0.3

Property and Equipment, net (De

Property and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 42,666	$ 37,109
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(27,990)	(23,102)
Property, Plant and Equipment, Net	14,676	14,007
Depreciation	5,478	5,358	$ 6,421
Disposal of Property Plant and Equipment	456	1,823	2,258
Gain (Loss) on Disposition of Assets	37	59	19
Full Depreciated Assets in Use	14,008	11,080
Internal-use software development costs capitalized	4,613	2,797	$ 1,048
Internal Use Software Developed, Subject To Amortization	2,819	1,000
Capitalized Computer Software, Amortization	1,054	100
Tangible Asset Impairment Charges	0
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 3,208	2,958
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 19,644	18,950
Computer Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Computer Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	5 years
Software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 5,432	5,430
Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	6 years
Software Development [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Property, Plant and Equipment, Gross	$ 8,775	4,102
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	Shorter of lease term or useful life
Property, Plant and Equipment, Gross	$ 5,587	5,650
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	20	19
Cloud-based product offerings [Member]
Property, Plant and Equipment [Line Items]
Internal-use software development costs capitalized	$ 4,673	$ 3,024

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Amortization of Intangible Assets	$ 7,600	$ 5,200	$ 3,000
Goodwill [Roll Forward]
Goodwill	38,458	20,096
Goodwill, Acquired During Period		17,052
Goodwill, Purchase Accounting Adjustments	252
Goodwill, Translation Adjustments	(479)	1,310
Goodwill	$ 38,231	$ 38,458	$ 20,096

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Translation Adjustments	$ 200	$ 700
Finite-Lived Intangible Assets, Gross	42,796	43,178
Finite-Lived Intangible Assets, Accumulated Amortization	23,442	16,249
Finite-Lived Intangible Assets, Net	$ 19,354	$ 26,929
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years	7 years
Finite-Lived Intangible Assets, Gross	$ 25,584	$ 26,023
Finite-Lived Intangible Assets, Accumulated Amortization	13,890	9,560
Finite-Lived Intangible Assets, Net	$ 11,694	$ 16,463
Maintenance relationship [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	8 years	8 years
Finite-Lived Intangible Assets, Gross	$ 3,485	$ 3,565
Finite-Lived Intangible Assets, Accumulated Amortization	2,488	2,207
Finite-Lived Intangible Assets, Net	$ 997	$ 1,358
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	6 years	6 years
Finite-Lived Intangible Assets, Gross	$ 11,802	$ 11,840
Finite-Lived Intangible Assets, Accumulated Amortization	6,884	4,482
Finite-Lived Intangible Assets, Net	$ 4,918	$ 7,358
Technology-Based Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	2 years	3 years
Finite-Lived Intangible Assets, Gross	$ 1,925	$ 1,750
Finite-Lived Intangible Assets, Accumulated Amortization	180	0
Finite-Lived Intangible Assets, Net	$ 1,745	$ 1,750

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets Future Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 6,575
Finite-Lived Intangible Assets, Amortization Expense, Year Two	5,791
Finite-Lived Intangible Assets, Amortization Expense, Year Three	3,021
Finite-Lived Intangible Assets, Amortization Expense, Year Four	1,921
Finite-Lived Intangible Assets, Amortization Expense, Year Five	1,292
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	754
Finite-Lived Intangible Assets, Net	$ 19,354	$ 26,929

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Treasury money market funds, at fair value	$ 268.6	$ 131.4
Cost Method Investments, Fair Value Disclosure	$ 2

Deferred Revenue and Performa_2

Deferred Revenue and Performance Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Deferred Revenue and Performance Obligation [Abstract]
Deferred Revenue, Revenue Recognized	$ 74.6	$ 65.6
Revenue, Remaining Performance Obligation	336.5
Revenue Remaining Performance Obligation, to be recognized within 12 months	$ 162.2

Stockholders Equity (Details)

Stockholders Equity (Details) $ in Millions	Dec. 31, 2018USD ($)
Stockholders' Equity Attributable to Parent [Abstract]
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 10
Stock Repurchase Program, Authorized Amount	$ 15

Stockholders Equity Secondary O

Stockholders Equity Secondary Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Secondary Offering [Abstract]
Shares, Issued	3,800,000
Shares Issued, Price Per Share	$ 34
Sale of Stock, Number of Shares Issued in Transaction	570,000
Proceeds from Issuance of Common Stock, Gross	$ 148,600
Proceeds from Issuance of Common Stock	$ 141,954	$ 0	$ 0

Earnings per Share Basis and Di

Earnings per Share Basis and Diluted (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
Numerator
Net income	$ (12,760)	$ (15,786)	$ (16,844)	$ (18,856)	$ (16,980)	$ (21,226)	$ (19,513)	$ (20,207)	$ (64,246)	$ (77,926)	$ (75,225)
Denominator
Weighted average shares (basic)									34,465	31,627	30,395
Dilutive effect of potential common shares									0	0	0
Weighted Average Number of Shares Outstanding, Basic and Diluted									34,465	31,627	30,395
Weighted Average Number of Shares Outstanding, Diluted									34,465	31,627	30,395
Basic earnings per share	$ (0.34)	$ (0.44)	$ (0.52)	$ (0.58)	$ (0.53)	$ (0.67)	$ (0.62)	$ (0.65)	$ (1.86)	$ (2.46)	$ (2.47)
Diluted earnings per share	$ (0.34)	$ (0.44)	$ (0.52)	$ (0.58)	$ (0.53)	$ (0.67)	$ (0.62)	$ (0.65)	$ (1.86)	$ (2.46)	$ (2.47)
Antidilutive potential common shares excluded from computation of earnings per share									2,100	2,000	1,769
Notes due 2019 [Member]
Denominator
Debt Instrument, Convertible, Stock Price Trigger									$ 33.79
Notes due 2047 [Member]
Denominator
Debt Instrument, Convertible, Stock Price Trigger									$ 48.63

Noncash Share-based Compensat_3

Noncash Share-based Compensation (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Stock options
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	0	135,000
Restricted stock unit - market-based [Member]
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	215,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	215,000	345,000
Restricted Stock Unit - time based [Member]
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,969,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	1,969,000	2,133,000
SARs
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	287,000	356,000
MSUs
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	419,000
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	419,000	387,000
2007 Equity Incentive Plan [Member]
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	1,908,003
2017 Equity Incentive Plan [Member] [Member]
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	981,746
2007 Equity Incentive Plan [Member] | RSUs
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	1,358,819
2007 Equity Incentive Plan [Member] | SARs
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	287,000
2007 Equity Incentive Plan [Member] | MSUs
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	262,600
2017 Equity Incentive Plan [Member] [Member]
Noncash Share-based Compensation (Narrative) [Line Items]
Shares reserved for issuance under Plan	2,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	1,347,240
2017 Equity Incentive Plan [Member] [Member] | RSUs
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	825,178
2017 Equity Incentive Plan [Member] [Member] | MSUs
Noncash Share-based Compensation (Narrative) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	156,568

Noncash Share-based Compensat_4

Noncash Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based compensation expense	$ 21,453	$ 22,796	$ 20,466
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 33,266
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	2 years 4 months 13 days
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based compensation expense	$ 1,721	1,971	2,267
Selling and Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based compensation expense	4,396	4,348	3,824
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based compensation expense	10,717	11,163	9,040
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based compensation expense	4,619	5,314	5,335
Stock compensation in operating expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based compensation expense	$ 19,732	$ 20,825	$ 18,199

Noncash Share-based Compensat_5

Noncash Share-based Compensation Noncash Share-based Compensation Share Based Compensation - Stock Option Rollforward (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock Unit - time based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number		1,969,000	2,133,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		829,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		1,969,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	[1]	$ 61,827
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(792,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(201,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number		1,902,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 27.61	$ 21.63	$ 11.69
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		20.49
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		20.45
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		21.77	$ 18.90
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price		$ 21.65
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term		2 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	[1]	$ 59,731
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms		2 years 7 days
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		0 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	[2]	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number		0	135,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price		$ 12.52
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price		0	$ 12.52
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term		0 years
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period		135,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price		$ 12.52
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures in Period		0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	[2]	$ 0
Restricted stock unit - market-based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		1 year 8 months 9 days
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number		215,000	345,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		0		460,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		215,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	[1]	$ 6,751
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(115,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		(15,000)
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number		211,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		12.61
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		9.98
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		9.98	$ 10.86
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price		$ 9.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term		1 year 8 months 9 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	[1]	$ 6,611
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	[3]	$ 5,869
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number		287,000	356,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Expired In Period, Weighted Average Grant Date Fair Value		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number		287,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price		$ 10.92
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price		$ 10.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price			$ 10.97
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term		1 year 10 months 10 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(69,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number		287,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		11.17
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Expirations		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 10.92
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price		$ 10.92
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term		1 year 10 months 10 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	[3]	$ 5,869
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value	[3]	$ 5,869
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms		1 year 10 months 10 days
Market Share Units (MSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number		419,000	387,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		117,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Expired In Period, Weighted Average Grant Date Fair Value		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number		419,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	[4]	$ 13,162
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		(85,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 38.18
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value		31.83
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value		$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Expirations		0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value		$ 25.90	$ 23.48
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms		1 year 1 month 6 days
[1]	The aggregate intrinsic value was calculated based on the fair value of the Company’s common stock on December 31, 2018 of $31.40.
[2]	The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the grant date fair value.
[3]	The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the exercise price of the underlying SARs.
[4]	The aggregate intrinsic value was calculated based on the positive difference between the estimated fair value of the Company’s common stock on December 31, 2018 of $31.40 and the grant date fair value of the underlying MSUs.

Noncash Share-based Compensat_6

Noncash Share-based Compensation Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shareholder return period for vesting of MSUs	3 years
Stock Price at Year End	$ 31.40
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 2,503,000	$ 7,185,000	$ 1,024,000
Shares issuable upon vesting of MSUs, maximum	200.00%
Share-based compensation arrangement by share-based payment, Minimum Employee Subscription rate	1.00%
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate	10.00%
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date	15.00%			5.00%
Maximum Amount Contributable by employees under ESPP- Half yearly	$ 5,000
Maximum Amount Contributable By Employees Under ESPP- Annually	$ 10,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	75,546
ESPP contributions by Employees	$ 943,000
Restricted stock unit - market-based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0		460,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	215,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	215,000	345,000
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price	$ 10.92
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	287,000	356,000
Market Share Units (MSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	117,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	419,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 38.18
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	419,000	387,000
Restricted Stock Unit - time based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	829,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,969,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 27.61	$ 21.63	$ 11.69
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	1,969,000	2,133,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	215,555
2007 Equity Incentive Plan [Member] | Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	287,000
2007 Equity Incentive Plan [Member] | Market Share Units (MSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	262,600
2007 Equity Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number	1,358,819
2007 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	1,908,003
Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards vesting upon Price Target	50.00%
Share Price Target	$ 41
Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards vesting upon Price Target	25.00%
Share Price Target	$ 27
Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Percentage of Awards vesting upon Price Target	25.00%
Share Price Target	$ 33

Noncash Share-based Compensat_7

Noncash Share-based Compensation Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	1 year 4 days
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	1 year 11 months 23 days
Restricted stock unit - market-based [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate			44.98%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate			1.08%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate			0.00%
Market Share Units (MSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	43.67%	45.38%	44.06%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	2.12%	1.56%	1.04%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	2 years 11 months 20 days	3 years 26 days	2 years 11 months 5 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%	0.00%	0.00%

Income Tax Disclosure Component

Income Tax Disclosure Components of Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)	$ (252)	$ 0	$ 19
Current State and Foreign	663	669	402
Current Income Tax Expense (Benefit)	411	669	421
Deferred Federal Income Tax Expense (Benefit)	(211)	(488)	51
Deferred State and Local Income Tax Expense (Benefit)	0	(32)	(2)
Income Tax Expense (Benefit)	$ 200	$ 149	$ 470

Income Tax Disclosure Reconcili

Income Tax Disclosure Reconciliation of Federal Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure - Reconciliation of Federal Tax Rate [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	$ (13,464)	$ (26,443)	$ (25,338)
Income Tax Reconciliation, State and Local Income Taxes	46	18	3
Income Tax Reconciliation, Nondeductible Expense	414	373	457
Income Tax Reconciliation, Nondeductible Expense, Other	0	245	(4)
Effective income tax reconciliation, Statutory to GAAP adjustments	(221)	(77)	(274)
Effective Income Tax Rate Reconciliation, Tax Expense, Foreign, Amount	0	0	2
Income Tax Reconciliation, Nondeductible Expense, Share-based Compensation Cost	(394)	(3,405)	604
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount	(153)	0	49
Income Tax Reconciliation, Tax Credits	(1,656)	(1,711)	(1,663)
Income Tax Reconciliation, Other Adjustments	(1,824)	2,625	0
Effective Income Tax Rate Reconciliation, Change related to Prior Years	(4,800)	(2,331)	(856)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	1,835	31,359	0
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance	20,417	(504)	27,490
Income Tax Expense (Benefit)	$ 200	$ 149	$ 470

Income Tax Disclosure Tax Effec

Income Tax Disclosure Tax Effect of Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure - Tax Effect of Temporary Differences [Abstract]
Deferred Tax Assets Property And Equipment Net	$ (528)	$ (847)
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits	6,922	6,373
Deferred Tax Asset, Disallowed Interest	4,574	0
Deferred Tax Liabilities, Deferred Expense, Capitalized Software	(1,533)	(1,397)
Deferred Tax Liabilities, Intangible Assets	(4,110)	(5,096)
Deferred Tax Assets, Tax Credit Carryforwards, Research	10,603	9,340
Deferred Tax Asset, Deferred Revenue	2,680	2,996
Deferred Tax Assets, Operating Loss Carryforwards	58,601	46,907
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	2,319	1,050
Tax Credit Carryforward, Deferred Tax Asset	2,005	1,613
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	8,945	9,057
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	2,462	2,521
Deferred Tax Assets, Other	1,291	1,425
Deferred Tax Assets, Net, Noncurrent	94,231	73,942
Deferred Tax Assets, Valuation Allowance, Noncurrent	(94,231)	(74,153)
Deferred Tax Liabilities, Net, Noncurrent	0	(211)
Deferred Tax Liability, Net	$ 0	$ (211)

Income Tax Disclosure Unrecogni

Income Tax Disclosure Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 183	$ 183	$ 192	$ 192
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	0	0	0
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	$ 0	$ (9)	$ 0

Income Tax Disclosure (Details)

Income Tax Disclosure (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate, Continuing Operations	0.00%	0.00%	(1.00%)
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 2,462,000	$ 2,521,000
Operating Loss Carryforwards	310,000,000
R&E tax credit carryforward for future use	12,600,000
Unrecognized Tax Benefits	183,000	183,000	$ 192,000	$ 192,000
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	1,835,000	$ 31,359,000	$ 0
Cameleon Acquistion [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 35,800,000

Convertible debt (Details)

Convertible debt (Details)	12 Months Ended
	Dec. 31, 2018USD ($)$ / shares	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Interest	$ 5,000,000	$ 3,991,000
Amortization of Financing Costs	1,419,000	1,127,000
Debt Instrument, Fair Value Disclosure	251,500,000	246,648,000
Debt Instrument, Face Amount	250,000,000	250,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	24,810,000	36,797,000
Convertible Debt	$ 225,190,000	213,203,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	2.00%
Debt Instrument, Convertible, Carrying Amount of Equity Component	$ 37,560,000	37,560,000
Amortization of Debt Discount (Premium)	10,567,000	8,100,000
Interest Expense, Debt	16,986,000	$ 13,218,000
Notes due 2019 [Member]
Debt Instrument [Line Items]
Convertible debt, issuance cost, equity component	$ 1,200,000
Debt Instrument, Convertible, Remaining Discount Amortization Period	11 months
Debt Instrument, Face Amount	$ 143,750,000
Purchase of convertible bond hedge	$ (29,411,000)
Investment Warrants, Exercise Price | $ / shares	$ 45.48
Proceeds from Issuance of Warrants	$ 17,106,000
Debt Instrument, Convertible, Conversion Ratio	29.5972
Debt Instrument, Convertible, Stock Price Trigger | $ / shares	$ 33.79
Debt Issuance Cost	$ 4,300,000
Debt Instrument, Convertible, Carrying Amount of Equity Component	28,714,000
Notes due 2047 [Member]
Debt Instrument [Line Items]
Convertible debt, issuance cost, equity component	$ 300,000
Debt Instrument, Convertible, Remaining Discount Amortization Period	41 months
Debt Instrument, Face Amount	$ 106,250,000
Debt Instrument, Convertible, Conversion Ratio	20.5624
Debt Instrument, Convertible, Stock Price Trigger | $ / shares	$ 48.63
Debt instrument, Convertible, Initial issue price per $1,000 of principal	$ 880
Debt Issuance Cost	2,700,000
Debt Instrument, Convertible, Carrying Amount of Equity Component	$ 8,846,000

Credit Facility (Details)

Credit Facility (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount	$ 50,000
Debt Instrument, Covenant, Minimum Liquidity	50,000
Unamortized Debt Issuance Expense	$ 145	$ 185
Minimum [Member] | LIBOR Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.50%
Minimum [Member] | Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	1.50%
Maximum [Member] | LIBOR Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.25%
Maximum [Member] | Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.25%

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Long-term Purchase Commitment [Line Items]
Contractual Obligation	$ 2.3
Operating Leases, Rent Expense, Net	4.3	$ 3.9	$ 4.1
December 2018 Agreement [Member] [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation	6.4
June 2017 Agreement [Member]
Long-term Purchase Commitment [Line Items]
Purchase Obligation	$ 12.6

Commitments and Contingencies F

Commitments and Contingencies Future minimum lease commitments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Future minimum lease commitments [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 4,164
Operating Leases, Future Minimum Payments, Due in Two Years	1,649
Operating Leases, Future Minimum Payments, Due in Three Years	5,115
Operating Leases, Future Minimum Payments, Due in Four Years	6,181
Operating Leases, Future Minimum Payments, Due in Five Years	5,679
Operating Leases, Future Minimum Payments, Due Thereafter	57,365
Operating Leases, Future Minimum Payments Due	$ 80,153

Segment and Geographical Info_3

Segment and Geographical Information International Revenue (Details) - USD ($) $ 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
Revenues from External Customers and Long-Lived Assets [Line Items]
International revenue									$ 128,542	$ 105,719	$ 96,502
Revenues	$ 52,613	$ 49,075	$ 47,426	$ 47,910	$ 46,344	$ 41,937	$ 40,406	$ 40,129	$ 197,024	$ 168,816	$ 153,276
percentage of total revenue									100.00%	100.00%	100.00%
International Revenue [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
percentage of total revenue									65.00%	63.00%	63.00%
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 68,482	$ 63,097	$ 56,774
percentage of total revenue									35.00%	37.00%	37.00%
South America and Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 18,378	$ 13,645	$ 9,335
percentage of total revenue									9.00%	8.00%	6.00%
North and South America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 86,860	$ 76,742	$ 66,109
percentage of total revenue									44.00%	45.00%	43.00%
GERMANY
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 20,171	$ 17,421	$ 10,042
percentage of total revenue									10.00%	10.00%	7.00%
The Rest of Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 40,776	$ 33,852	$ 34,613
percentage of total revenue									21.00%	20.00%	23.00%
Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 32,090	$ 26,528	$ 30,457
percentage of total revenue									16.00%	16.00%	20.00%
Middle East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 15,092	$ 11,437	$ 10,567
percentage of total revenue									8.00%	7.00%	7.00%
Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 2,035	$ 2,836	$ 1,488
percentage of total revenue									1.00%	2.00%	1.00%

Concentrations of Risk (Details

Concentrations of Risk (Details)	12 Months Ended
	Dec. 31, 2018
Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	10.00%
Accounts Receivable [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	10.00%

Employment Retirement Savings (

Employment Retirement Savings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 2.4	$ 2	$ 1.9
Matching Percentage of Salary Contribution by Qualified Employees	50.00%
Qualified Employees Contribution Matching Percentage by the Employer	6.00%

Quarterly Results Quarterly F_2

Quarterly Results Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ 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 Financial Information Disclosure [Abstract]
Revenues	$ 52,613	$ 49,075	$ 47,426	$ 47,910	$ 46,344	$ 41,937	$ 40,406	$ 40,129	$ 197,024	$ 168,816	$ 153,276
Gross Profit	33,155	29,599	28,702	28,389	28,197	24,213	24,320	23,520	119,845	100,250	89,923
Operating Income (Loss)	(9,609)	(11,866)	(12,993)	(14,747)	(12,815)	(17,750)	(16,710)	(17,668)	(49,215)	(64,943)	(65,398)
Net Income (Loss) Attributable to Parent	$ (12,760)	$ (15,786)	$ (16,844)	$ (18,856)	$ (16,980)	$ (21,226)	$ (19,513)	$ (20,207)	$ (64,246)	$ (77,926)	$ (75,225)
Basic earnings per share	$ (0.34)	$ (0.44)	$ (0.52)	$ (0.58)	$ (0.53)	$ (0.67)	$ (0.62)	$ (0.65)	$ (1.86)	$ (2.46)	$ (2.47)
Diluted	$ (0.34)	$ (0.44)	$ (0.52)	$ (0.58)	$ (0.53)	$ (0.67)	$ (0.62)	$ (0.65)	$ (1.86)	$ (2.46)	$ (2.47)

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Balance		$ 760	$ 760	$ 586
Valuation Allowances and Reserves, Charged to Cost and Expense		223	0	887
Valuation Allowances and Reserves, Deductions	[1]	0	0	(713)
Valuation Allowances and Reserves, Charged to Other Accounts		(5)	0	0
Valuation Allowances and Reserves, Balance		978	760	760
Valuation Allowance of Deferred Tax Assets [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation Allowances and Reserves, Balance		74,153	69,049	44,321
Valuation Allowances and Reserves, Charged to Cost and Expense		20,417	5,872	26,634
Valuation Allowances and Reserves, Deductions		0	0	0
Valuation Allowances and Reserves, Charged to Other Accounts	[2]	(339)	(768)	(1,906)
Valuation Allowances and Reserves, Balance		$ 94,231	$ 74,153	$ 69,049
[1]	Deductions column represents the reversal of additions previously charged to costs and expenses and uncollectible accounts written off, net of recoveries.
[2]	Other column represents the cumulative translation adjustment impact on the allowance.