Medidata Solutions 10-Q 10 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 03, 2019
Document and Entity Information [Abstract]
Entity registrant name	Medidata Solutions, Inc.
Entity central index key	0001453814
Document type	10-Q
Amendment flag	false
Document period end date	Mar. 31, 2019
Document fiscal period focus	Q1
Document fiscal year focus	2019
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Entity small business	false
Entity emerging growth company	false
Entity common stock, shares outstanding		62,260,585

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents		$ 109,052	$ 105,440
Marketable securities		97,060	135,105
Accounts receivable, net of allowance for doubtful accounts	[1]	177,853	170,744
Prepaid commission expense		23,186	22,247
Prepaid expenses and other current assets		36,817	28,949
Total current assets		443,968	462,485
Restricted cash		7,212	7,205
Operating lease assets	[2]	86,383	0
Furniture, fixtures and equipment, net		111,035	98,983
Goodwill		215,958	216,017
Intangible assets, net		28,276	29,546
Deferred income taxes- long-term		46,503	45,982
Other assets		57,367	52,994
Total assets		996,702	913,212
Current liabilities:
Accounts payable		8,137	7,482
Accrued payroll and other compensation		31,823	51,270
Accrued expenses and other		46,785	37,487
Operating lease liabilities	[2]	14,286	0
Deferred revenue		71,591	74,463
Total current liabilities		172,622	170,702
Noncurrent liabilities:
Term loans, net		86,606	88,366
Deferred revenue, less current portion		2,424	3,843
Deferred tax liabilities		98	99
Operating lease liabilities, noncurrent	[2]	96,585	0
Other long-term liabilities		1,641	18,754
Total noncurrent liabilities		187,354	111,062
Total liabilities		359,976	281,764
Commitments and contingencies
Stockholders' equity:
Preferred stock		0	0
Common stock		674	661
Additional paid-in capital		596,725	574,667
Treasury stock		(181,553)	(152,849)
Accumulated other comprehensive loss		(4,103)	(4,869)
Retained earnings		224,983	213,838
Total stockholders' equity		636,726	631,448
Total liabilities and stockholders' equity		$ 996,702	$ 913,212
[1]	Unbilled receivables of $48,648 and $38,601, respectively, are included in accounts receivable as of March 31, 2019 and December 31, 2018.
[2]	Figures as of March 31, 2019 reflect the Company's January 1, 2019 adoption of Accounting Standards Update ("ASU") No. 2016-02, Leases. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounts receivable, allowance for doubtful accounts	$ 1,959	$ 1,999
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000	200,000
Common stock, shares issued	67,434	66,103
Common stock, shares outstanding	62,246	61,348
Treasury stock, shares	5,188	4,755

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Revenues:
Revenues		$ 173,504	$ 149,198
Cost of revenues:
Cost of revenues		46,003	36,302
Gross profit		127,501	112,896
Operating costs and expenses:
Research and development	[1]	46,489	37,522
Sales and marketing	[1],[2]	43,396	36,861
General and administrative	[1]	32,634	25,187
Total operating costs and expenses		122,519	99,570
Operating income		4,982	13,326
Interest and other income (expense):
Interest expense		(1,110)	(5,575)
Interest income		945	2,088
Other income (expense), net		(28)	(96)
Total interest and other expense, net		(193)	(3,583)
Income before income taxes		4,789	9,743
Provision for income taxes		(6,356)	(582)
Net income		$ 11,145	$ 10,325
Earnings per share:
Basic		$ 0.19	$ 0.18
Diluted		$ 0.18	$ 0.17
Weighted average common shares outstanding, basic		59,693	57,055
Weighted average common shares outstanding, diluted		61,755	60,098
Share-based compensation and amortization of intangible assets:
Total stock-based compensation	[1]	$ 19,664	$ 13,155
Total amortization of intangible assets	[2]	1,870	1,214
Cost of revenues
Share-based compensation and amortization of intangible assets:
Total stock-based compensation	[1]	2,383	1,268
Total amortization of intangible assets	[2]	1,364	1,094
Research and development
Share-based compensation and amortization of intangible assets:
Total stock-based compensation	[1]	4,249	2,854
Sales and marketing
Share-based compensation and amortization of intangible assets:
Total stock-based compensation	[1]	5,426	2,644
Total amortization of intangible assets	[2]	506	120
General and administrative
Share-based compensation and amortization of intangible assets:
Total stock-based compensation	[1]	7,606	6,389
Subscription [Member]
Revenues:
Revenues		146,875	126,819
Cost of revenues:
Cost of revenues		26,728	20,341
Professional services [Member]
Revenues:
Revenues		26,629	22,379
Cost of revenues:
Cost of revenues		$ 19,275	$ 15,961
[1]	Stock-based compensation expense included in cost of revenues and operating costs and expenses
[2]	Amortization of intangible assets included in cost of revenues and operating costs and expenses

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net income	$ 11,145	$ 10,325
Other comprehensive income (loss):
Foreign currency translation adjustments	372	1,270
Unrealized gain (loss) on marketable securities	532	(1,026)
Other comprehensive income (loss)	904	244
Income tax effect of unrealized gain or loss on marketable securities	(138)	58
Other comprehensive income (loss), net of tax	766	302
Comprehensive income (loss), net of tax	$ 11,911	$ 10,627

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income		$ 11,145	$ 10,325
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of intangible assets and depreciation		10,529	7,813
Stock-based compensation	[1]	19,664	13,155
Amortization of operating lease assets	[2]	3,025	0
Amortization of capitalized contract costs		6,583	4,919	[3]
Amortization of discounts or premiums on marketable securities		38	147
Realized loss on available-for-sale securities		27	0
Deferred income taxes		(659)	818
Amortization of debt issuance costs		109	427
Amortization of debt discount		0	3,481
Provision for doubtful accounts		431	373
Loss on fixed asset disposal		101	96
Changes in fair value of contingent consideration		161	(72)
Changes in operating assets and liabilities:
Accounts receivable		(7,540)	(23,141)
Prepaid commission expense		(12,054)	(10,619)	[3]
Prepaid expenses and other current assets		(2,820)	(658)
Other assets		159	125
Accounts payable		1,361	2,600
Accrued payroll and other compensation		(24,174)	(13,711)
Accrued expenses and other		7,668	(778)
Deferred revenue		(4,291)	9,440
Operating lease liabilities	[2]	(3,858)	0
Other long-term liabilities		479	236
Net cash provided by (used in) operating activities		6,084	4,976
Cash flows from investing activities:
Purchases of furniture, fixtures and equipment		(18,188)	(11,147)
Purchase of domain name		(600)	0
Purchases of available-for-sale securities		0	(57,974)
Proceeds from sale of available-for-sale securities		38,512	64,202
Net cash provided by (used in) investing activities		19,724	(4,919)
Cash flows from financing activities:
Proceeds from exercise of stock options		2,341	2,366
Proceeds from employee stock purchase plan		3,408	3,121
Acquisition of treasury stock		(26,616)	(16,614)
Term loan principal payments		(1,250)	0
Payment of acquisition-related earn-out		(297)	(87)
Payments of credit facility financing costs		0	(175)
Net cash provided by (used in) financing activities		(22,414)	(11,389)
Effect of exchange rate changes on cash, cash equivalents and restricted cash		225	597
Net increase (decrease) in cash, cash equivalents and restricted cash		3,619	(10,735)
Cash, cash equivalents and restricted cash - beginning of period		112,645	242,843
Cash, cash equivalents and restricted cash - end of period		116,264	232,108
Supplemental disclosures of cash flow information:
Interest paid		990	2,200
Proceeds from income tax refunds		(1,053)
Income taxes paid			1,099
Noncash activities:
Furniture, fixtures, and equipment acquired but not yet paid for at period-end		$ 6,801	$ 3,901
[1]	Stock-based compensation expense included in cost of revenues and operating costs and expenses
[2]	Figures as of March 31, 2019 reflect the Company's January 1, 2019 adoption of Accounting Standards Update ("ASU") No. 2016-02, Leases. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."
[3]	Prior period recast to conform with current period presentation

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Medidata Solutions, Inc., together with its consolidated subsidiaries (collectively, the "Company"), is the leading global provider of cloud-based solutions for clinical research in life sciences, offering platform technology that transforms clinical development and increases the value of its customers' research investments. The Company was organized as a New York corporation in June 1999 and reincorporated as a Delaware corporation in May 2000. Except to the extent updated or described below, the Company’s significant accounting policies as of March 31, 2019 are the same as those at December 31, 2018 , which are included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 , filed with the Securities and Exchange Commission (“SEC”) on March 1, 2019 . Basis of Presentation — The accompanying interim condensed consolidated balance sheets as of March 31, 2019 and December 31, 2018 , the condensed consolidated statements of operations for the three months ended March 31, 2019 and 2018 , the condensed consolidated statements of comprehensive income for the three months ended March 31, 2019 and 2018 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the SEC for interim financial reporting. Accordingly, certain information and footnote disclosures have been condensed or omitted pursuant to SEC rules that would ordinarily be required by U.S. GAAP for complete financial statements. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and accompanying notes thereto for the fiscal year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 1, 2019 . The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments consisting of normal recurring accruals considered necessary to present fairly the Company’s financial position as of March 31, 2019 , results of its operations for the three months ended March 31, 2019 and 2018 , comprehensive income for the three months ended March 31, 2019 and 2018 , and cash flows for the three months ended March 31, 2019 and 2018 . The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 . Accounts Receivable — Accounts receivable are recorded at original invoice amount less an allowance that management believes will be adequate to absorb estimated losses on uncollectible accounts. This allowance is based on an evaluation of the collectability of accounts receivable and prior bad debt experience. Accounts receivable are written off when deemed uncollectible. Unbilled receivables consist of revenue recognized in excess of billings, substantially all of which is expected to be billed and collected within one year. As of March 31, 2019 and December 31, 2018 , unbilled accounts receivable of $48.6 million and $38.6 million , respectively, were included in accounts receivable on the Company's condensed consolidated balance sheets. Leases — At the inception of an arrangement, the Company evaluates the existence and type of lease; the Company has determined that all of its leases are operating leases, which are recognized as operating lease assets and operating lease liabilities on its condensed consolidated balance sheet as of March 31, 2019 (subsequent to the adoption of Accounting Standards Codification ("ASC") 842, Leases on January 1, 2019). Operating lease assets represent the right to use an underlying asset over the lease term, and operating lease liabilities represent the obligation to make lease payments. Some of the Company's leases contain options to extend or terminate; the Company is reasonably certain that it will not exercise these options and does not consider them in the determination of the lease term. Leases with an initial term of twelve months or less are not recorded on the balance sheet; the Company recognizes the related expense on a straight-line basis over the lease term. For leases beginning in 2019 and later, the Company accounts for lease components together with nonlease components. Operating lease assets and liabilities are recognized based on the present value of the remaining lease payments as of the commencement date. As the majority of its leases do not provide an implicit interest rate, the Company uses the estimated incremental borrowing rate that would be required to secure a loan from a third-party lender over the relevant term. For further information, see Note 8 , “Leases.". Income Taxes — The Company’s interim period provision for income taxes is computed by using an estimate of the annual effective tax rate, adjusted for discrete items taken into account in the relevant period, if any. Each quarter, the annual effective income tax rate is recomputed and if there are material changes in the estimate, a cumulative adjustment is made. Recently Adopted Accounting Pronouncements — In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases , which replaces previous lease guidance in its entirety with ASC 842 and requires lessees to recognize lease assets and lease liabilities for those arrangements classified as operating leases under previous guidance, with the exception of leases with a term of twelve months or less. The Company adopted ASU No. 2016-02 on January 1, 2019 using the additional transition method, which allows prior periods to be presented under previous lease accounting guidance. Refer to Note 8 , "Leases," for related disclosures. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, which permits companies to reclassify disproportionate tax effects in accumulated other comprehensive income caused by the U.S. Tax Cuts and Jobs Act enacted in December 2017 to retained earnings. ASU No. 2018-02 is effective for annual reporting periods beginning after December 15, 2018, and interim periods within those annual periods. The Company adopted ASU No. 2018-02 on January 1, 2019, and the adoption did not have a material impact on its condensed consolidated financial statements. Recently Issued Accounting Pronouncements — There have been no changes in the expected dates of adoption or estimated effects on the Company's consolidated financial statements of recently issued accounting pronouncements from those disclosed in the Company’s Annual Report on Form 10-K.

Revenues

Revenues	3 Months Ended
	Mar. 31, 2019
Revenues [Abstract]
REVENUES	REVENUES Disaggregation of Revenue The following tables provide information about the Company's revenues, disaggregated by geographical market and revenue type, for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Subscription Professional Services Total Subscription Professional Services Total Revenues: United States $ 108,836 $ 17,517 $ 126,353 $ 96,165 $ 15,984 $ 112,149 Rest of Americas 1,803 239 2,042 1,115 376 1,491 Total Americas 110,639 17,756 128,395 97,280 16,360 113,640 Japan 10,897 2,473 13,370 8,112 1,794 9,906 Rest of Asia Pacific 6,004 1,736 7,740 3,701 977 4,678 Total Asia Pacific 16,901 4,209 21,110 11,813 2,771 14,584 Europe, Middle East and Africa 19,335 4,664 23,999 17,726 3,248 20,974 Total $ 146,875 $ 26,629 $ 173,504 $ 126,819 $ 22,379 $ 149,198 The above tables present revenues according to the region in which they were generated, separately displaying those individual countries that, in any of the periods presented, constituted 5% or more or of total revenues. All of the Company's performance obligations are transferred to customers over time; as a result, no disaggregation of revenues by timing of revenue recognition is provided. Contract Balances The following table provides information about changes in the Company's deferred revenue balances during the three months ended March 31, 2019 and 2018 (in thousands): Deferred Revenue 2019 2018 Balance as of January 1 $ 78,306 $ 82,631 Revenue recognized that was included in deferred revenue at the beginning of the period (51,444 ) (63,720 ) Revenue recognized that was not included in deferred revenue at the beginning of the period (116,052 ) (85,275 ) Increases due to invoicing 155,583 155,416 Revenue recognized in excess of billings 10,048 2,688 Other (2,426 ) 331 Balance as of March 31 $ 74,015 $ 92,071 Aside from the accounts receivable presented on its condensed consolidated balance sheets, the Company did not have any material contract assets for any of the periods presented. Transaction Price Allocated to the Remaining Performance Obligations As of March 31, 2019 , the Company has unsatisfied performance obligations associated with subscription services that extend through 2030 . The total multi-year transaction price allocated to unsatisfied subscription performance obligations is approximately $1,042 million as of March 31, 2019 . Of this amount, approximately $407 million , $377 million , and $258 million are expected to be recognized in 2019 , 2020 , and thereafter, respectively. As of March 31, 2019 , the total transaction price allocated to unsatisfied professional services performance obligations is immaterial. Costs to Obtain and Fulfill a Contract with a Customer Sales commissions earned are considered incremental and recoverable costs of obtaining a contract with a customer and therefore are capitalized as contract costs. Capitalized contract costs were $65.5 million and $60.0 million as of March 31, 2019 and December 31, 2018 , respectively. The current portion of capitalized contract costs is represented by capitalized contract costs on the Company's consolidated balance sheets; the long-term portion is included in other assets. Amortization of capitalized contract costs was $6.6 million and $4.9 million for the three months ended March 31, 2019 and 2018 , respectively. There have been no impairment losses related to capitalized contract costs.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Common Stock — Common stockholders are entitled to one vote for each share of common stock held. Common stockholders may receive dividends if and when the board of directors determines, at its sole discretion. Treasury Stock — From time to time, the Company grants nonvested restricted stock awards ("RSAs"), restricted stock units ("RSUs"), and performance-based restricted stock units ("PBRSUs") to its employees pursuant to the terms of its Amended and Restated 2017 Long-Term Incentive Plan ("2017 Plan") and formerly pursuant to the terms of its Second Amended and Restated 2009 Long-Term Incentive Plan ("2009 Plan”). Under the provisions of the 2017 Plan and 2009 Plan, unless otherwise elected, participants fulfill their related income tax obligation by having shares withheld at the time of vesting. On the date of vesting, the Company divides the participant's income tax withholding obligation in dollars by the closing price of its common stock and withholds the resulting number of vested shares. The shares withheld are then transferred to the Company's treasury stock at cost. During the three months ended March 31, 2019 and 2018 , the Company withheld 393,249 shares at an average price of $72.99 and 248,831 shares at an average price of $66.77 , respectively, in connection with the vesting of equity awards. Nonvested restricted stock awards forfeited by plan participants are transferred to the Company's treasury stock at par. During the three months ended March 31, 2019 and 2018 , 40,281 and 42,176 forfeited shares, respectively, were transferred to treasury stock at their par value of $0.01. Accumulated Other Comprehensive Loss — For the three months ended March 31, 2019 and 2018 , reclassifications of items from accumulated other comprehensive loss to net income were insignificant. The following reconciliation presents significant changes in the components of stockholders' equity for the three months ended March 31, 2019 and 2018 (in thousands): Accumulated other comprehensive loss (amounts in thousands) Common stock Additional paid-in capital Treasury stock Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Retained earnings Total Balance - January 1, 2019 $ 661 $ 574,667 $ (152,849 ) $ (4,255 ) $ (614 ) $ 213,838 $ 631,448 Comprehensive income, net — — — 372 394 11,145 11,911 Stock-based compensation — 19,730 — — — — 19,730 Issuance of shares under stock-based compensation plans 13 2,328 — — — — 2,341 Acquisition of treasury stock in connection with award vesting — — (28,704 ) — — — (28,704 ) Balance - March 31, 2019 $ 674 $ 596,725 $ (181,553 ) $ (3,883 ) $ (220 ) $ 224,983 $ 636,726 Accumulated other comprehensive loss (amounts in thousands) Common stock Additional paid-in capital Treasury stock Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Retained earnings Total Balance - January 1, 2018 628 486,147 (132,705 ) (2,459 ) (918 ) 161,917 512,610 Comprehensive income, net — — — 1,270 (968 ) 10,325 10,627 Stock-based compensation — 13,214 — — — — 13,214 Issuance of shares under stock-based compensation plans 9 2,357 — — — — 2,366 Acquisition of treasury stock in connection with award vesting — — (16,614 ) — — — (16,614 ) Balance - March 31, 2018 $ 637 $ 501,718 $ (149,319 ) $ (1,189 ) $ (1,886 ) $ 172,242 $ 522,203

Investments

Investments	3 Months Ended
	Mar. 31, 2019
Investments [Abstract]
INVESTMENTS	INVESTMENTS Marketable Securities Marketable securities, which the Company classifies as available-for-sale securities, primarily consist of high quality commercial paper, corporate bonds, and U.S. government debt obligations. Marketable securities with remaining effective maturities of twelve months or less from the balance sheet date are classified as short-term; otherwise, they are classified as long-term on the condensed consolidated balance sheets. The following tables provide the Company’s marketable securities by security type as of March 31, 2019 and December 31, 2018 (in thousands): As of March 31, 2019 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 86,668 $ — $ (251 ) $ 86,417 U.S. government agency debt securities 10,690 — (47 ) 10,643 Total $ 97,358 $ — $ (298 ) $ 97,060 As of December 31, 2018 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 125,245 $ — $ (747 ) $ 124,498 U.S. government agency debt securities 10,690 — (83 ) 10,607 Total $ 135,935 $ — $ (830 ) $ 135,105 Contractual maturities of the Company’s marketable securities as of March 31, 2019 and December 31, 2018 are summarized as follows (in thousands): As of March 31, 2019 As of December 31, 2018 Cost Estimated Fair Value Cost Estimated Fair Value Due in one year or less $ 97,358 $ 97,060 $ 135,935 $ 135,105 Due in one to five years — — — — Total $ 97,358 $ 97,060 $ 135,935 $ 135,105 At March 31, 2019 , the Company had $0.3 million of gross unrealized losses primarily due to a decrease in the fair value of certain corporate bonds. The Company regularly reviews its investment portfolio to identify and evaluate investments that have indications of possible impairment. Investments that are impaired are those that are considered to have losses that are other-than-temporary. Factors considered in determining whether a loss is temporary include: • the length of time and extent to which fair value has been lower than the cost basis; • the financial condition, credit quality and near-term prospects of the investee; and • whether it is more likely than not that the Company will be required to sell the security prior to recovery. As the Company has the ability and intent to hold these investments until a recovery of fair value, which may be maturity, the Company has determined that the gross unrealized losses on such investments at March 31, 2019 are temporary in nature. Accordingly, the Company did not consider its investments in marketable securities to be other-than-temporarily impaired as of March 31, 2019 . The following table provides the fair market value and gross unrealized losses of the Company's marketable securities with unrealized losses, aggregated by security type, as of March 31, 2019 and December 31, 2018 (in thousands): In Loss Position for More than 12 Months As of March 31, 2019 As of December 31, 2018 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 86,416 $ (251 ) $ 124,498 $ (747 ) U.S. government agency debt securities 10,643 (47 ) 10,607 (83 ) Total $ 97,059 $ (298 ) $ 135,105 $ (830 ) During the three months ended March 31, 2019 and 2018 , the Company recorded an insignificant amount of net realized gains and losses from the sale of marketable securities. Other Investments The Company holds shares of Series D Preferred Stock of Syapse Inc. purchased in a private placement. This investment does not have a readily determinable fair value and is carried at original cost in other assets on the Company's condensed consolidated balance sheets. This investment had a carrying value of $3.0 million as of March 31, 2019 and December 31, 2018 . The Company periodically evaluates this investment to determine if impairment charges are required; no impairment charges were recognized during the three months ended March 31, 2019 or 2018 .

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUE The following table summarizes, as of March 31, 2019 and December 31, 2018 , the Company's financial assets and liabilities that are measured at fair value on a recurring basis, according to the fair value hierarchy described in the significant accounting policies included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 (in thousands): As of March 31, 2019 As of December 31, 2018 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 108,292 $ — $ — $ 108,292 $ 103,859 $ — $ — $ 103,859 Money market funds 760 — — 760 1,581 — — 1,581 Total cash and cash equivalents 109,052 — — 109,052 105,440 — — 105,440 Commercial paper and corporate bonds — 86,416 — 86,416 — 124,498 — 124,498 U.S. government agency debt securities — 10,644 — 10,644 — 10,607 — 10,607 Total marketable securities — 97,060 — 97,060 — 135,105 — 135,105 Total financial assets measured at fair value on a recurring basis $ 109,052 $ 97,060 $ — $ 206,112 $ 105,440 $ 135,105 $ — $ 240,545 Contingent consideration – short-term $ — $ — $ 974 $ 974 $ — $ — $ 1,110 $ 1,110 Total financial liabilities measured at fair value on a recurring basis $ — $ — $ 974 $ 974 $ — $ — $ 1,110 $ 1,110 Investments in commercial paper, corporate bonds, and U.S. government agency debt securities have been classified as Level 2 as they are valued using quoted prices in less active markets or other directly or indirectly observable inputs. Fair values of corporate bonds and U.S. government agency debt securities were derived from a consensus or weighted-average price based on input of market prices from multiple sources at each reporting period. With regard to commercial paper, all of the securities had high credit ratings and one year or less to maturity; therefore, fair value was derived from accretion of purchase price to face value over the term of maturity or quoted market prices for similar instruments if available. During the three months ended March 31, 2019 and 2018 , there were no transfers of financial assets between Level 1 and Level 2. Contingent consideration liabilities associated with earn-out payments related to the Company's February 2017 acquisition of CHITA Inc. ("CHITA") are classified as Level 3 in the fair value hierarchy because they rely significantly on inputs that are unobservable in the market. The fair value of portions of contingent consideration related to the achievement of a technical milestone have been estimated using situation-based modeling, which considers the probability-weighted present value of the expected payout amount. The fair value of portions of contingent consideration related to achievement of revenue targets have been estimated using a Monte Carlo simulation to simulate future performance of the acquired business under a risk-neutral framework; significant inputs to the simulation include a risk-adjusted discount rate of 10.2% and revenue volatility of 8.0%. Contingent consideration is recorded in accrued expenses and other on the Company's condensed consolidated balance sheets. The following table provides a summary of changes in fair value of the Company's Level 3 contingent consideration liabilities during the three months ended March 31, 2019 (in thousands): Balance as of January 1, 2019 $ 1,110 Amounts earned by sellers (297 ) Fair value adjustment (included in general and administrative expenses) 161 Balance as of March 31, 2019 $ 974 The carrying amounts of all other current financial assets and current financial liabilities reflected in the condensed consolidated balance sheets approximate fair value due to their short-term nature.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS The change in the carrying amount of goodwill during the three months ended March 31, 2019 was as follows (in thousands): Balance as of January 1, 2019 $ 216,017 Purchase price adjustment - SHYFT Analytics, Inc. (149 ) Foreign currency translation adjustments 90 Balance as of March 31, 2019 $ 215,958 Total intangible assets are summarized as follows (in thousands): As of March 31, 2019 As of December 31, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 31,384 $ (15,243 ) $ 16,141 $ 31,358 $ (13,852 ) $ 17,506 Customer relationships 9,175 (3,711 ) 5,464 9,167 (3,404 ) 5,763 Trade name 5,400 (280 ) 5,120 5,400 (190 ) 5,210 Non-competition agreements 1,460 (509 ) 951 1,460 (393 ) 1,067 Domain name (1) 600 — 600 — — — Total $ 48,019 $ (19,743 ) $ 28,276 $ 47,385 $ (17,839 ) $ 29,546 (1) During the three months ended March 31, 2019, the Company purchased the domain name medidata.com, which is considered to have an indefinite life. Future amortization of intangible assets is expected to be as follows (in thousands): Remainder of 2019 $ 5,603 2020 6,730 2021 6,249 2022 3,465 2023 1,849 Thereafter 3,780 Total $ 27,676

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
DEBT	DEBT Credit Facility The Company's credit facility agreement (the "Credit Facility"), entered into in December 2017, consists of revolving commitments with a maximum borrowing amount of $400.0 million (the "Revolver"), currently undrawn, and term loans (the "Term Loans") in an aggregate principal amount of $100.0 million . The repayment terms of the Term Loans provide for monthly interest payments and quarterly principal payments, with a maturity date of December 2022. The Credit Facility consisted of the following components as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 December 31, 2018 Term Loans $ 93,750 $ 95,000 Less: unamortized debt issuance costs (1,616 ) (1,725 ) Net carrying amount (1) $ 92,134 $ 93,275 (1) Of the total carrying amount of the Term Loans, short-term maturities of $5.5 million and $4.9 million were included in accrued expenses and other on the Company's condensed consolidated balance sheets as of March 31, 2019 and December 31, 2018, respectively. The following table sets forth total interest expense recognized related to the Credit Facility for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Contractual interest expense on Term Loans $ 854 $ 748 Amortization of debt issuance costs 109 108 Unused commitment fee on Revolver 147 200 Total $ 1,110 $ 1,056 Contractual interest rate on Term Loans 3.624 % 3.229 % Commitment fee rate on undrawn Revolver 0.150 % 0.200 % As of March 31, 2019 the remaining term of the Credit Facility is approximately 45 months . The Company was in compliance with all financial covenants related to the Credit Facility as of March 31, 2019 . 1.00% Convertible Senior Notes The Company's 1.00% convertible senior notes (the "Notes") were issued in August 2013 and settled on August 1, 2018 . Interest expense related to the Notes for the three months ended March 31, 2018 was $4.5 million , consisting of contractual interest expense of $0.7 million , amortization of debt issuance costs of $0.3 million , and amortization of debt discount of $3.5 million .

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
LEASES	LEASES The Company leases office and data center space under operating lease agreements with remaining lease terms extending through 2031. During the three months ended March 31, 2019 and 2018 , the Company recognized operating lease costs of $4.8 million and $3.9 million , respectively; for the three months ended March 31, 2019 , operating lease costs include $0.2 million of short-term lease costs. Supplemental cash flow information related to leases for the three months ended March 31, 2019 was as follows (in thousands): Three months ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Cash paid for operating leases $ (3,858 ) Noncash activities: Right-of-use assets obtained in exchange for new operating lease liabilities (1) $ — (1) No new operating leases were entered into during the three months ended March 31, 2019; all new operating lease liabilities recorded during the period are the result of the Company's January 1, 2019 adoption of ASC 842. As of March 31, 2019 , the weighted-average remaining lease term for operating lease liabilities was approximately 7.4 years and the weighted-average discount rate was approximately 3.59% . Maturities of operating lease liabilities are as follows (in thousands): Remainder of 2019 $ 13,316 2020 19,391 2021 19,118 2022 18,792 2023 18,072 Thereafter 38,667 Total lease payments 127,356 Less imputed interest (16,485 ) Total present value of operating lease liabilities $ 110,871

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION For the three months ended March 31, 2019 and 2018 , the components of stock-based compensation expense were as follows (in thousands): Three Months Ended March 31, 2019 2018 Stock options $ 471 $ 572 Restricted stock awards and units 12,739 7,867 Performance-based restricted stock units 4,735 3,227 Employee stock purchase plan 1,785 1,548 Total stock-based compensation (1) $ 19,730 $ 13,214 (1) Total stock-based compensation is presented in this table on a gross basis, consistent with the additional paid-in capital impact recorded in stockholders' equity. On the Company's condensed consolidated statements of operations and condensed consolidated statements of cash flows, stock-based compensation is presented net of foreign exchange impact and capitalization of eligible software development-related costs. Stock Options The following table summarizes the status of the Company's stock options as of March 31, 2019 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2019 1,088 $19.17 Granted — — Exercised (57 ) 41.15 Forfeited — — Expired (1 ) 13.99 Outstanding at March 31, 2019 1,030 $17.96 2.60 $57,037 Exercisable at March 31, 2019 919 $12.82 1.95 $55,553 Vested and expected to vest at March 31, 2019 1,025 $17.71 2.58 $56,992 No stock options were granted during the three months ended March 31, 2019 and 2018 . The total intrinsic value of stock options exercised during the three months ended March 31, 2019 and 2018 was $1.9 million and $7.6 million , respectively. As of March 31, 2019 , there was $2.5 million in unrecognized compensation cost related to all non-vested stock options granted. This cost is expected to be recognized over a weighted-average remaining period of 2.08 years . R estricted Stock Awards and Units The following table summarizes the status of the Company’s nonvested time-based RSAs and RSUs as of March 31, 2019 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Grant-Date Fair Value Nonvested at January 1, 2019 1,936 $61.45 Granted 909 71.42 Vested (516 ) 52.83 Forfeited (44 ) 60.55 Nonvested at March 31, 2019 2,285 $67.38 The total fair value of RSAs and RSUs vested during the three months ended March 31, 2019 and 2018 was $ 38.2 million and $31.6 million , respectively. As of March 31, 2019 , there was $136.3 million in unrecognized compensation cost related to all nonvested RSAs and RSUs granted. This cost is expected to be recognized over a weighted-average remaining period of 2.79 years . Performance-Based Restricted Stock Units During the three months March 31, 2019 , the Company granted: (1) 155 thousand PBRSUs ("2019 TSR PBRSUs") with market conditions based on the Company's total stockholder return ("TSR") relative to that of the Russell 2000 Index over the three-year period ending December 31, 2021, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares ; (2) 155 thousand PBRSUs ("2019 Revenue PBRSUs") with performance conditions based on the compound annual growth rate of revenue over the three-year period ending December 31, 2021, vesting in full in three years with the number of shares ultimately earned ranging from zero to 250% of the target number of shares . During the three months March 31, 2018 , the Company granted: (1) 116 thousand PBRSUs ("2018 TSR PBRSUs") with market conditions based on the Company's TSR relative to that of the Russell 2000 Index over the three-year period ending December 31, 2020, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares ; (2) 117 thousand PBRSUs ("2018 Net Income PBRSUs") with performance conditions based on the compound annual growth rate of net income over the three-year period ending December 31, 2020, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares . The Company also granted an immaterial number of other PBRSUs with performance conditions based on achievement of certain individual and team objectives. The fair value of PBRSUs with market conditions granted during the three months ended March 31, 2019 and 2018 was estimated as of the date of grant using a Monte Carlo valuation model with the following weighted average assumptions: Three Months Ended March 31, 2019 2018 Expected volatility - Medidata 35 % 37 % Expected volatility - comparison index 44 % 42 % Expected life 2.88 years 2.86 years Risk-free interest rate 2.47 % 2.36 % Dividend yield — — The following table summarizes the status of the Company’s PBRSUs based upon expected performance as of March 31, 2019 , and changes during the three months then ended (in thousands, except per share data): Net Income TSR Revenue Other Total Number of Shares Weighted-Average Grant Date Fair Value Nonvested at January 1, 2019 210 793 — 23 1,026 $ 70.80 Granted (based on performance at 100% of targeted levels) — 155 155 — 310 88.56 Adjustment related to expected performance — 6 — — 6 104.54 Vested — (370 ) — — (370 ) 47.11 Forfeited — — — — — 77.64 Nonvested at March 31, 2019 210 584 155 23 972 $ 85.69 The total fair value of PBRSUs vested during the three months ended March 31, 2019 and 2018 was $26.6 million and $8.1 million , respectively. As of March 31, 2019 , there was $44.6 million in unrecognized compensation cost related to all nonvested PBRSUs. This cost is expected to be recognized over a weighted-average remaining period of 1.94 years . Employee Stock Purchase Plan The fair value of shares granted under the Company's employee stock purchase plan ("ESPP") was estimated using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended March 31, 2019 2018 Expected volatility 34 % 37 % Expected life 1.54 years 1.69 years Risk-free interest rate 2.39 % 1.10 % Dividend yield — — No shares were purchased under the ESPP during the three months ended March 31, 2019 and 2018 . As of March 31, 2019 , there was $10.1 million in unrecognized compensation cost related to ESPP shares. This cost is expected to be recognized over a weighted-average remaining period of 1.42 years. Modifications Aggregate incremental expense associated with modifications to stock options, RSAs and PBRSUs in connection with separation agreements during the three months ended March 31, 2019 and 2018 was $0.1 million and $0.2 million , respectively.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per share is calculated by dividing net income available to common stockholders by the weighted-average number of shares outstanding during the period. The holders of unvested RSAs do not have nonforfeitable rights to dividends or dividend equivalents and therefore, such vested awards do not qualify as participating securities and are excluded from the basic earnings per share calculation. Diluted earnings per share includes the determinants of basic net income per share and, in addition, gives effect to the potential dilution that would occur if securities or other contracts to issue common stock are exercised, vested, or converted into common stock, unless they are anti-dilutive. In August 2018, the Company settled the principal amount of the Notes in cash and issued shares of common stock to settle the conversion premium. For the three months ended March 31, 2018 , the dilutive effect of the Notes is reflected in diluted earnings per share using the treasury stock method, which considers the number of shares that would have been required to settle the premium above principal at the average stock price for the period. A reconciliation of the numerator and denominator of basic earnings per share and diluted earnings per share for the three months ended March 31, 2019 and 2018 is shown in the following table (in thousands, except per share data): Three Months Ended March 31, 2019 2018 Numerator Net income $ 11,145 $ 10,325 Denominator Denominator for basic earnings per share: Weighted average common shares outstanding 59,693 57,055 Denominator for diluted earnings per share: Dilutive potential common shares: Stock options 775 922 Restricted stock awards and units 676 743 Performance-based restricted stock units 558 494 Employee stock purchase plan 53 250 Convertible senior notes — 634 Weighted average common shares outstanding with assumed conversion 61,755 60,098 Basic earnings per share $ 0.19 $ 0.18 Diluted earnings per share $ 0.18 $ 0.17 Anti-dilutive common stock equivalents excluded from the calculation of diluted earnings per share for the three months ended March 31, 2019 and 2018 are presented in the following table (in thousands, except per share data): Three Months Ended March 31, 2019 2018 Stock options 81 94 Restricted stock awards and units 28 263 Performance-based restricted stock units 84 54 Employee stock purchase plan 581 188 Total 774 599

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Unrecognized Tax Benefits The Company's unrecognized tax benefits were approximately $6.4 million as of March 31, 2019 , and were unchanged from December 31, 2018 .

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Matters — The Company is subject to legal proceedings and claims that arise in the ordinary course of business and records an estimated liability for these matters when an adverse outcome is considered to be probable and can be reasonably estimated. Although the outcome of the litigation cannot be predicted with certainty and some lawsuits, claims, or proceedings may be disposed of unfavorably to the Company, which could materially and adversely affect its financial condition or results of operations, the Company does not believe that it is currently a party to any material legal proceedings. Contractual Warranties — The Company typically provides contractual warranties to its customers covering its solutions and services. To date, any refunds provided to customers have been immaterial. Change in Control Agreements — The Company has change in control agreements with its chief executive officer and certain other executive officers. These agreements provide for payments to be made to such officers upon involuntary termination of their employment by the Company without cause or by such officers for good reason as defined in the agreements, within a period of 2 years following a change in control. The agreements provide that, upon a qualifying termination event, such officers will be entitled to (a) a severance payment equal to the sum of the officer’s base salary and target bonus amount (except that such payment for the Company's chief executive officer and president would be two times such sum); (b) continuation of health benefits for one year (except that such continuation for the Company's chief executive officer and president would be for two years); and (c) immediate vesting of remaining unvested equity awards, unless otherwise specified in the equity award agreements.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of presentation	Basis of Presentation — The accompanying interim condensed consolidated balance sheets as of March 31, 2019 and December 31, 2018 , the condensed consolidated statements of operations for the three months ended March 31, 2019 and 2018 , the condensed consolidated statements of comprehensive income for the three months ended March 31, 2019 and 2018 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2019 and 2018 are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the SEC for interim financial reporting. Accordingly, certain information and footnote disclosures have been condensed or omitted pursuant to SEC rules that would ordinarily be required by U.S. GAAP for complete financial statements. These unaudited interim condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and accompanying notes thereto for the fiscal year ended December 31, 2018 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 1, 2019 . The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments consisting of normal recurring accruals considered necessary to present fairly the Company’s financial position as of March 31, 2019 , results of its operations for the three months ended March 31, 2019 and 2018 , comprehensive income for the three months ended March 31, 2019 and 2018 , and cash flows for the three months ended March 31, 2019 and 2018 . The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 .
Accounts receivable	Accounts Receivable — Accounts receivable are recorded at original invoice amount less an allowance that management believes will be adequate to absorb estimated losses on uncollectible accounts. This allowance is based on an evaluation of the collectability of accounts receivable and prior bad debt experience. Accounts receivable are written off when deemed uncollectible. Unbilled receivables consist of revenue recognized in excess of billings, substantially all of which is expected to be billed and collected within one year. As of March 31, 2019 and December 31, 2018 , unbilled accounts receivable of $48.6 million and $38.6 million , respectively, were included in accounts receivable on the Company's condensed consolidated balance sheets.
Leases	Leases — At the inception of an arrangement, the Company evaluates the existence and type of lease; the Company has determined that all of its leases are operating leases, which are recognized as operating lease assets and operating lease liabilities on its condensed consolidated balance sheet as of March 31, 2019 (subsequent to the adoption of Accounting Standards Codification ("ASC") 842, Leases on January 1, 2019). Operating lease assets represent the right to use an underlying asset over the lease term, and operating lease liabilities represent the obligation to make lease payments. Some of the Company's leases contain options to extend or terminate; the Company is reasonably certain that it will not exercise these options and does not consider them in the determination of the lease term. Leases with an initial term of twelve months or less are not recorded on the balance sheet; the Company recognizes the related expense on a straight-line basis over the lease term. For leases beginning in 2019 and later, the Company accounts for lease components together with nonlease components. Operating lease assets and liabilities are recognized based on the present value of the remaining lease payments as of the commencement date. As the majority of its leases do not provide an implicit interest rate, the Company uses the estimated incremental borrowing rate that would be required to secure a loan from a third-party lender over the relevant term.
Income taxes	Income Taxes — The Company’s interim period provision for income taxes is computed by using an estimate of the annual effective tax rate, adjusted for discrete items taken into account in the relevant period, if any. Each quarter, the annual effective income tax rate is recomputed and if there are material changes in the estimate, a cumulative adjustment is made.
Recently issued accounting pronouncements	Recently Adopted Accounting Pronouncements — In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases , which replaces previous lease guidance in its entirety with ASC 842 and requires lessees to recognize lease assets and lease liabilities for those arrangements classified as operating leases under previous guidance, with the exception of leases with a term of twelve months or less. The Company adopted ASU No. 2016-02 on January 1, 2019 using the additional transition method, which allows prior periods to be presented under previous lease accounting guidance. Refer to Note 8 , "Leases," for related disclosures. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, which permits companies to reclassify disproportionate tax effects in accumulated other comprehensive income caused by the U.S. Tax Cuts and Jobs Act enacted in December 2017 to retained earnings. ASU No. 2018-02 is effective for annual reporting periods beginning after December 15, 2018, and interim periods within those annual periods. The Company adopted ASU No. 2018-02 on January 1, 2019, and the adoption did not have a material impact on its condensed consolidated financial statements. Recently Issued Accounting Pronouncements — There have been no changes in the expected dates of adoption or estimated effects on the Company's consolidated financial statements of recently issued accounting pronouncements from those disclosed in the Company’s Annual Report on Form 10-K.
Recently issued and adopted accounting pronouncements	Recently Adopted Accounting Pronouncements — In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases , which replaces previous lease guidance in its entirety with ASC 842 and requires lessees to recognize lease assets and lease liabilities for those arrangements classified as operating leases under previous guidance, with the exception of leases with a term of twelve months or less. The Company adopted ASU No. 2016-02 on January 1, 2019 using the additional transition method, which allows prior periods to be presented under previous lease accounting guidance. Refer to Note 8 , "Leases," for related disclosures. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, which permits companies to reclassify disproportionate tax effects in accumulated other comprehensive income caused by the U.S. Tax Cuts and Jobs Act enacted in December 2017 to retained earnings. ASU No. 2018-02 is effective for annual reporting periods beginning after December 15, 2018, and interim periods within those annual periods. The Company adopted ASU No. 2018-02 on January 1, 2019, and the adoption did not have a material impact on its condensed consolidated financial statements. Recently Issued Accounting Pronouncements — There have been no changes in the expected dates of adoption or estimated effects on the Company's consolidated financial statements of recently issued accounting pronouncements from those disclosed in the Company’s Annual Report on Form 10-K.
Earnings per share	Basic earnings per share is calculated by dividing net income available to common stockholders by the weighted-average number of shares outstanding during the period. The holders of unvested RSAs do not have nonforfeitable rights to dividends or dividend equivalents and therefore, such vested awards do not qualify as participating securities and are excluded from the basic earnings per share calculation. Diluted earnings per share includes the determinants of basic net income per share and, in addition, gives effect to the potential dilution that would occur if securities or other contracts to issue common stock are exercised, vested, or converted into common stock, unless they are anti-dilutive. In August 2018, the Company settled the principal amount of the Notes in cash and issued shares of common stock to settle the conversion premium. For the three months ended March 31, 2018 , the dilutive effect of the Notes is reflected in diluted earnings per share using the treasury stock method, which considers the number of shares that would have been required to settle the premium above principal at the average stock price for the period.

Revenues (Tables)

Revenues (Tables)	3 Months Ended
	Mar. 31, 2019
Revenues [Abstract]
Disaggregation of revenue	The following tables provide information about the Company's revenues, disaggregated by geographical market and revenue type, for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Subscription Professional Services Total Subscription Professional Services Total Revenues: United States $ 108,836 $ 17,517 $ 126,353 $ 96,165 $ 15,984 $ 112,149 Rest of Americas 1,803 239 2,042 1,115 376 1,491 Total Americas 110,639 17,756 128,395 97,280 16,360 113,640 Japan 10,897 2,473 13,370 8,112 1,794 9,906 Rest of Asia Pacific 6,004 1,736 7,740 3,701 977 4,678 Total Asia Pacific 16,901 4,209 21,110 11,813 2,771 14,584 Europe, Middle East and Africa 19,335 4,664 23,999 17,726 3,248 20,974 Total $ 146,875 $ 26,629 $ 173,504 $ 126,819 $ 22,379 $ 149,198
Contract balances	The following table provides information about changes in the Company's deferred revenue balances during the three months ended March 31, 2019 and 2018 (in thousands): Deferred Revenue 2019 2018 Balance as of January 1 $ 78,306 $ 82,631 Revenue recognized that was included in deferred revenue at the beginning of the period (51,444 ) (63,720 ) Revenue recognized that was not included in deferred revenue at the beginning of the period (116,052 ) (85,275 ) Increases due to invoicing 155,583 155,416 Revenue recognized in excess of billings 10,048 2,688 Other (2,426 ) 331 Balance as of March 31 $ 74,015 $ 92,071

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Schedule of stockholders' equity	The following reconciliation presents significant changes in the components of stockholders' equity for the three months ended March 31, 2019 and 2018 (in thousands): Accumulated other comprehensive loss (amounts in thousands) Common stock Additional paid-in capital Treasury stock Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Retained earnings Total Balance - January 1, 2019 $ 661 $ 574,667 $ (152,849 ) $ (4,255 ) $ (614 ) $ 213,838 $ 631,448 Comprehensive income, net — — — 372 394 11,145 11,911 Stock-based compensation — 19,730 — — — — 19,730 Issuance of shares under stock-based compensation plans 13 2,328 — — — — 2,341 Acquisition of treasury stock in connection with award vesting — — (28,704 ) — — — (28,704 ) Balance - March 31, 2019 $ 674 $ 596,725 $ (181,553 ) $ (3,883 ) $ (220 ) $ 224,983 $ 636,726 Accumulated other comprehensive loss (amounts in thousands) Common stock Additional paid-in capital Treasury stock Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Retained earnings Total Balance - January 1, 2018 628 486,147 (132,705 ) (2,459 ) (918 ) 161,917 512,610 Comprehensive income, net — — — 1,270 (968 ) 10,325 10,627 Stock-based compensation — 13,214 — — — — 13,214 Issuance of shares under stock-based compensation plans 9 2,357 — — — — 2,366 Acquisition of treasury stock in connection with award vesting — — (16,614 ) — — — (16,614 ) Balance - March 31, 2018 $ 637 $ 501,718 $ (149,319 ) $ (1,189 ) $ (1,886 ) $ 172,242 $ 522,203

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2019
Investments [Abstract]
Marketable securities by security type	The following tables provide the Company’s marketable securities by security type as of March 31, 2019 and December 31, 2018 (in thousands): As of March 31, 2019 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 86,668 $ — $ (251 ) $ 86,417 U.S. government agency debt securities 10,690 — (47 ) 10,643 Total $ 97,358 $ — $ (298 ) $ 97,060 As of December 31, 2018 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 125,245 $ — $ (747 ) $ 124,498 U.S. government agency debt securities 10,690 — (83 ) 10,607 Total $ 135,935 $ — $ (830 ) $ 135,105
Contractual maturities of marketable securities	Contractual maturities of the Company’s marketable securities as of March 31, 2019 and December 31, 2018 are summarized as follows (in thousands): As of March 31, 2019 As of December 31, 2018 Cost Estimated Fair Value Cost Estimated Fair Value Due in one year or less $ 97,358 $ 97,060 $ 135,935 $ 135,105 Due in one to five years — — — — Total $ 97,358 $ 97,060 $ 135,935 $ 135,105
Fair market value and gross unrealized losses of marketable securities	The following table provides the fair market value and gross unrealized losses of the Company's marketable securities with unrealized losses, aggregated by security type, as of March 31, 2019 and December 31, 2018 (in thousands): In Loss Position for More than 12 Months As of March 31, 2019 As of December 31, 2018 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 86,416 $ (251 ) $ 124,498 $ (747 ) U.S. government agency debt securities 10,643 (47 ) 10,607 (83 ) Total $ 97,059 $ (298 ) $ 135,105 $ (830 )

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Financial assets and liabilities measured at fair value on a recurring basis	The following table summarizes, as of March 31, 2019 and December 31, 2018 , the Company's financial assets and liabilities that are measured at fair value on a recurring basis, according to the fair value hierarchy described in the significant accounting policies included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 (in thousands): As of March 31, 2019 As of December 31, 2018 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 108,292 $ — $ — $ 108,292 $ 103,859 $ — $ — $ 103,859 Money market funds 760 — — 760 1,581 — — 1,581 Total cash and cash equivalents 109,052 — — 109,052 105,440 — — 105,440 Commercial paper and corporate bonds — 86,416 — 86,416 — 124,498 — 124,498 U.S. government agency debt securities — 10,644 — 10,644 — 10,607 — 10,607 Total marketable securities — 97,060 — 97,060 — 135,105 — 135,105 Total financial assets measured at fair value on a recurring basis $ 109,052 $ 97,060 $ — $ 206,112 $ 105,440 $ 135,105 $ — $ 240,545 Contingent consideration – short-term $ — $ — $ 974 $ 974 $ — $ — $ 1,110 $ 1,110 Total financial liabilities measured at fair value on a recurring basis $ — $ — $ 974 $ 974 $ — $ — $ 1,110 $ 1,110
Changes in fair value of level 3 liabilities	The following table provides a summary of changes in fair value of the Company's Level 3 contingent consideration liabilities during the three months ended March 31, 2019 (in thousands): Balance as of January 1, 2019 $ 1,110 Amounts earned by sellers (297 ) Fair value adjustment (included in general and administrative expenses) 161 Balance as of March 31, 2019 $ 974

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of goodwill	The change in the carrying amount of goodwill during the three months ended March 31, 2019 was as follows (in thousands): Balance as of January 1, 2019 $ 216,017 Purchase price adjustment - SHYFT Analytics, Inc. (149 ) Foreign currency translation adjustments 90 Balance as of March 31, 2019 $ 215,958
Intangible assets	Total intangible assets are summarized as follows (in thousands): As of March 31, 2019 As of December 31, 2018 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 31,384 $ (15,243 ) $ 16,141 $ 31,358 $ (13,852 ) $ 17,506 Customer relationships 9,175 (3,711 ) 5,464 9,167 (3,404 ) 5,763 Trade name 5,400 (280 ) 5,120 5,400 (190 ) 5,210 Non-competition agreements 1,460 (509 ) 951 1,460 (393 ) 1,067 Domain name (1) 600 — 600 — — — Total $ 48,019 $ (19,743 ) $ 28,276 $ 47,385 $ (17,839 ) $ 29,546 (1) During the three months ended March 31, 2019, the Company purchased the domain name medidata.com, which is considered to have an indefinite life.
Annual amortization for the next five years	Future amortization of intangible assets is expected to be as follows (in thousands): Remainder of 2019 $ 5,603 2020 6,730 2021 6,249 2022 3,465 2023 1,849 Thereafter 3,780 Total $ 27,676

Debt (Tables)

Debt (Tables) - Credit facility [Member]	3 Months Ended
	Mar. 31, 2019
Debt Instrument [Line Items]
Schedule of debt	The Credit Facility consisted of the following components as of March 31, 2019 and December 31, 2018 (in thousands): March 31, 2019 December 31, 2018 Term Loans $ 93,750 $ 95,000 Less: unamortized debt issuance costs (1,616 ) (1,725 ) Net carrying amount (1) $ 92,134 $ 93,275 (1) Of the total carrying amount of the Term Loans, short-term maturities of $5.5 million and $4.9 million were included in accrued expenses and other on the Company's condensed consolidated balance sheets as of March 31, 2019 and December 31, 2018, respectively.
Interest expense	The following table sets forth total interest expense recognized related to the Credit Facility for the three months ended March 31, 2019 and 2018 (in thousands): Three Months Ended March 31, 2019 2018 Contractual interest expense on Term Loans $ 854 $ 748 Amortization of debt issuance costs 109 108 Unused commitment fee on Revolver 147 200 Total $ 1,110 $ 1,056 Contractual interest rate on Term Loans 3.624 % 3.229 % Commitment fee rate on undrawn Revolver 0.150 % 0.200 %

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Supplemental cash flow information related to operating leases	Supplemental cash flow information related to leases for the three months ended March 31, 2019 was as follows (in thousands): Three months ended March 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: Cash paid for operating leases $ (3,858 ) Noncash activities: Right-of-use assets obtained in exchange for new operating lease liabilities (1) $ — (1) No new operating leases were entered into during the three months ended March 31, 2019; all new operating lease liabilities recorded during the period are the result of the Company's January 1, 2019 adoption of ASC 842.
Maturities of operating lease liabilities	Maturities of operating lease liabilities are as follows (in thousands): Remainder of 2019 $ 13,316 2020 19,391 2021 19,118 2022 18,792 2023 18,072 Thereafter 38,667 Total lease payments 127,356 Less imputed interest (16,485 ) Total present value of operating lease liabilities $ 110,871

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Components of stock-based compensation expense	For the three months ended March 31, 2019 and 2018 , the components of stock-based compensation expense were as follows (in thousands): Three Months Ended March 31, 2019 2018 Stock options $ 471 $ 572 Restricted stock awards and units 12,739 7,867 Performance-based restricted stock units 4,735 3,227 Employee stock purchase plan 1,785 1,548 Total stock-based compensation (1) $ 19,730 $ 13,214 (1) Total stock-based compensation is presented in this table on a gross basis, consistent with the additional paid-in capital impact recorded in stockholders' equity. On the Company's condensed consolidated statements of operations and condensed consolidated statements of cash flows, stock-based compensation is presented net of foreign exchange impact and capitalization of eligible software development-related costs.
Fair value of stock option grants - N/A
Summary of activities and changes in stock option plans	The following table summarizes the status of the Company's stock options as of March 31, 2019 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2019 1,088 $19.17 Granted — — Exercised (57 ) 41.15 Forfeited — — Expired (1 ) 13.99 Outstanding at March 31, 2019 1,030 $17.96 2.60 $57,037 Exercisable at March 31, 2019 919 $12.82 1.95 $55,553 Vested and expected to vest at March 31, 2019 1,025 $17.71 2.58 $56,992
Summary of nonvested restricted stock awards	The following table summarizes the status of the Company’s nonvested time-based RSAs and RSUs as of March 31, 2019 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Grant-Date Fair Value Nonvested at January 1, 2019 1,936 $61.45 Granted 909 71.42 Vested (516 ) 52.83 Forfeited (44 ) 60.55 Nonvested at March 31, 2019 2,285 $67.38
Fair value of TSR PBRSUs	The fair value of PBRSUs with market conditions granted during the three months ended March 31, 2019 and 2018 was estimated as of the date of grant using a Monte Carlo valuation model with the following weighted average assumptions: Three Months Ended March 31, 2019 2018 Expected volatility - Medidata 35 % 37 % Expected volatility - comparison index 44 % 42 % Expected life 2.88 years 2.86 years Risk-free interest rate 2.47 % 2.36 % Dividend yield — —
Summary of performance-based restricted stock units based on expected performance	The following table summarizes the status of the Company’s PBRSUs based upon expected performance as of March 31, 2019 , and changes during the three months then ended (in thousands, except per share data): Net Income TSR Revenue Other Total Number of Shares Weighted-Average Grant Date Fair Value Nonvested at January 1, 2019 210 793 — 23 1,026 $ 70.80 Granted (based on performance at 100% of targeted levels) — 155 155 — 310 88.56 Adjustment related to expected performance — 6 — — 6 104.54 Vested — (370 ) — — (370 ) 47.11 Forfeited — — — — — 77.64 Nonvested at March 31, 2019 210 584 155 23 972 $ 85.69
Fair value of employee stock purchase plan shares	The fair value of shares granted under the Company's employee stock purchase plan ("ESPP") was estimated using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended March 31, 2019 2018 Expected volatility 34 % 37 % Expected life 1.54 years 1.69 years Risk-free interest rate 2.39 % 1.10 % Dividend yield — —

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Reconciliation of the numerators and denominators of basic and diluted earnings per share	A reconciliation of the numerator and denominator of basic earnings per share and diluted earnings per share for the three months ended March 31, 2019 and 2018 is shown in the following table (in thousands, except per share data): Three Months Ended March 31, 2019 2018 Numerator Net income $ 11,145 $ 10,325 Denominator Denominator for basic earnings per share: Weighted average common shares outstanding 59,693 57,055 Denominator for diluted earnings per share: Dilutive potential common shares: Stock options 775 922 Restricted stock awards and units 676 743 Performance-based restricted stock units 558 494 Employee stock purchase plan 53 250 Convertible senior notes — 634 Weighted average common shares outstanding with assumed conversion 61,755 60,098 Basic earnings per share $ 0.19 $ 0.18 Diluted earnings per share $ 0.18 $ 0.17
Schedule of antidilutive securities excluded from computation of earnings per share	Anti-dilutive common stock equivalents excluded from the calculation of diluted earnings per share for the three months ended March 31, 2019 and 2018 are presented in the following table (in thousands, except per share data): Three Months Ended March 31, 2019 2018 Stock options 81 94 Restricted stock awards and units 28 263 Performance-based restricted stock units 84 54 Employee stock purchase plan 581 188 Total 774 599

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Unbilled receivables	$ 48.6	$ 38.6

Revenues (Details)

Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 173,504	$ 149,198
United States
Disaggregation of Revenue [Line Items]
Revenues	126,353	112,149
Rest of Americas [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,042	1,491
Total Americas [Member]
Disaggregation of Revenue [Line Items]
Revenues	128,395	113,640
Japan
Disaggregation of Revenue [Line Items]
Revenues	13,370	9,906
Rest of Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	7,740	4,678
Total Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	21,110	14,584
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	23,999	20,974
Subscription [Member]
Disaggregation of Revenue [Line Items]
Revenues	146,875	126,819
Subscription [Member] | United States
Disaggregation of Revenue [Line Items]
Revenues	108,836	96,165
Subscription [Member] | Rest of Americas [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,803	1,115
Subscription [Member] | Total Americas [Member]
Disaggregation of Revenue [Line Items]
Revenues	110,639	97,280
Subscription [Member] | Japan
Disaggregation of Revenue [Line Items]
Revenues	10,897	8,112
Subscription [Member] | Rest of Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	6,004	3,701
Subscription [Member] | Total Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	16,901	11,813
Subscription [Member] | Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	19,335	17,726
Professional services [Member]
Disaggregation of Revenue [Line Items]
Revenues	26,629	22,379
Professional services [Member] | United States
Disaggregation of Revenue [Line Items]
Revenues	17,517	15,984
Professional services [Member] | Rest of Americas [Member]
Disaggregation of Revenue [Line Items]
Revenues	239	376
Professional services [Member] | Total Americas [Member]
Disaggregation of Revenue [Line Items]
Revenues	17,756	16,360
Professional services [Member] | Japan
Disaggregation of Revenue [Line Items]
Revenues	2,473	1,794
Professional services [Member] | Rest of Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	1,736	977
Professional services [Member] | Total Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	4,209	2,771
Professional services [Member] | Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	$ 4,664	$ 3,248

Revenues (Details 1)

Revenues (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Change in contract liabilities
Contract liabilities, balance at beginning of period	$ 78,306	$ 82,631
Revenue recognized that was included in deferred revenue at the beginning of the period	(51,444)	(63,720)
Revenue recognized that was not included in deferred revenue at the beginning of the period	(116,052)	(85,275)
Increase due to invoicing	155,583	155,416
Revenue recognized in excess of billings	10,048	2,688
Other	(2,426)	331
Contract liabilities, balance at end of period	$ 74,015	$ 92,071

Revenues (Details Textual)

Revenues (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Revenues [Abstract]
Basis for disaggregation	The above tables present revenues according to the region in which they were generated, separately displaying those individual countries that, in any of the periods presented, constituted 5% or more or of total revenues.
Performance obligations, description of timing	All of the Company's performance obligations are transferred to customers over time; as a result, no disaggregation of revenues by timing of revenue recognition is provided.
Year through which remaining performance obligations extend	2030
Unsatisfied subscription performance obligations	$ 1,042
Unsatisfied subscription performance obligations, portion expected to be satisfied in current fiscal year	407
Unsatisfied subscription performance obligations, portion expected to be satisfied in following fiscal year	377
Unsatisfied subscription performance obligations, portion expected to be satisfied thereafter	$ 258
Capitalized cost, judgment	Sales commissions earned are considered incremental and recoverable costs of obtaining a contract with a customer and therefore are capitalized as contract costs.
Capitalized contract costs	$ 65.5		$ 60
Capitalized contract costs, amortization	6.6	$ 4.9
Capitalized contract costs, accumulated impairment	$ 0

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stockholders' equity - beginning of period	$ 631,448	$ 512,610
Comprehensive income (loss), net of tax	11,911	10,627
Stock-based compensation	19,730	13,214
Issuance of shares under stock-based compensation plans	2,341	2,366
Acquisition of treasury stock in connection with award vesting	(28,704)	(16,614)
Stockholders' equity - end of period	636,726	522,203
Common stock [Member]
Stockholders' equity - beginning of period	661	628
Comprehensive income (loss), net of tax	0	0
Stock-based compensation	0	0
Issuance of shares under stock-based compensation plans	13	9
Acquisition of treasury stock in connection with award vesting	0	0
Stockholders' equity - end of period	674	637
Additional paid-in capital [Member]
Stockholders' equity - beginning of period	574,667	486,147
Comprehensive income (loss), net of tax	0	0
Stock-based compensation	19,730	13,214
Issuance of shares under stock-based compensation plans	2,328	2,357
Acquisition of treasury stock in connection with award vesting	0	0
Stockholders' equity - end of period	596,725	501,718
Treasury stock [Member]
Stockholders' equity - beginning of period	(152,849)	(132,705)
Comprehensive income (loss), net of tax	0	0
Stock-based compensation	0	0
Issuance of shares under stock-based compensation plans	0	0
Acquisition of treasury stock in connection with award vesting	(28,704)	(16,614)
Stockholders' equity - end of period	(181,553)	(149,319)
Foreign currency translation adjustments
Stockholders' equity - beginning of period	(4,255)	(2,459)
Comprehensive income (loss), net of tax	372	1,270
Stock-based compensation	0	0
Issuance of shares under stock-based compensation plans	0	0
Acquisition of treasury stock in connection with award vesting	0	0
Stockholders' equity - end of period	(3,883)	(1,189)
Unrealized gains (losses) on marketable securities
Stockholders' equity - beginning of period	(614)	(918)
Comprehensive income (loss), net of tax	394	(968)
Stock-based compensation	0	0
Issuance of shares under stock-based compensation plans	0	0
Acquisition of treasury stock in connection with award vesting	0	0
Stockholders' equity - end of period	(220)	(1,886)
Retained earnings [Member]
Stockholders' equity - beginning of period	213,838	161,917
Comprehensive income (loss), net of tax	11,145	10,325
Stock-based compensation	0	0
Issuance of shares under stock-based compensation plans	0	0
Acquisition of treasury stock in connection with award vesting	0	0
Stockholders' equity - end of period	$ 224,983	$ 172,242

Stockholders' Equity (Details T

Stockholders' Equity (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Equity [Abstract]
Shares paid for tax withholding for share based compensation	393,249	248,831
Shares paid for tax withholding for share based compensation, average price	$ 72.99	$ 66.77
Forfeited restricted stock awards transferred to treasury stock	40,281	42,176
Reclassifications from accumulated other comprehensive income	$ (27)	$ 0

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Marketable securities by security type
Cost	$ 97,358	$ 135,935
Gross unrealized gains	0	0
Gross unrealized losses	(298)	(830)
Estimated fair value	97,060	135,105
Commercial paper and corporate bonds [Member]
Marketable securities by security type
Cost	86,668	125,245
Gross unrealized gains	0	0
Gross unrealized losses	(251)	(747)
Estimated fair value	86,417	124,498
U.S. government agency debt securities [Member]
Marketable securities by security type
Cost	10,690	10,690
Gross unrealized gains	0	0
Gross unrealized losses	(47)	(83)
Estimated fair value	$ 10,643	$ 10,607

Investments (Details 1)

Investments (Details 1) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Marketable securities by contractual maturity
Cost	$ 97,358	$ 135,935
Estimated fair value	97,060	135,105
Due in one year or less [Member]
Marketable securities by contractual maturity
Cost	97,358	135,935
Estimated fair value	97,060	135,105
Due in one to five years [Member]
Marketable securities by contractual maturity
Cost	0	0
Estimated fair value	$ 0	$ 0

Investments (Details 2)

Investments (Details 2) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair market value and gross unrealized losses of marketable securities
12 months or more in unrealized loss position - fair value	$ 97,059	$ 135,105
12 months or more in unrealized loss position - gross unrealized losses	(298)	(830)
Commercial paper and corporate bonds [Member]
Fair market value and gross unrealized losses of marketable securities
12 months or more in unrealized loss position - fair value	86,416	124,498
12 months or more in unrealized loss position - gross unrealized losses	(251)	(747)
U.S. government agency debt securities [Member]
Fair market value and gross unrealized losses of marketable securities
12 months or more in unrealized loss position - fair value	10,643	10,607
12 months or more in unrealized loss position - gross unrealized losses	$ (47)	$ (83)

Investments (Details Textual)

Investments (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Investment [Line Items]
Net realized gains (losses) from the sale of marketable securities	$ (27)	$ 0
Syapse [Member]
Investment [Line Items]
Investments without readily determinable fair value, description	The Company holds shares of Series D Preferred Stock of Syapse Inc. purchased in a private placement. This investment does not have a readily determinable fair value and is carried at original cost in other assets on the Company's condensed consolidated balance sheets.
Investments without readily determinable fair value, original cost	$ 3,000		$ 3,000
Investments without readily determinable fair value, impairments recognized	$ 0	$ 0

Fair Value (Details)

Fair Value (Details) - Fair value, recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents	$ 109,052	$ 105,440
Marketable securities	97,060	135,105
Total financial assets	206,112	240,545
Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	974	1,110
Total financial liabilities	974	1,110
Cash [Member]
Assets
Cash and cash equivalents	108,292	103,859
Money market funds [Member]
Assets
Cash and cash equivalents	760	1,581
Commercial paper and corporate bonds [Member]
Assets
Marketable securities	86,416	124,498
U.S. government agency debt securities [Member]
Assets
Marketable securities	10,644	10,607
Level 1 [Member]
Assets
Cash and cash equivalents	109,052	105,440
Marketable securities	0	0
Total financial assets	109,052	105,440
Level 1 [Member] | Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	0	0
Total financial liabilities	0	0
Level 1 [Member] | Cash [Member]
Assets
Cash and cash equivalents	108,292	103,859
Level 1 [Member] | Money market funds [Member]
Assets
Cash and cash equivalents	760	1,581
Level 1 [Member] | Commercial paper and corporate bonds [Member]
Assets
Marketable securities	0	0
Level 1 [Member] | U.S. government agency debt securities [Member]
Assets
Marketable securities	0	0
Level 2 [Member]
Assets
Cash and cash equivalents	0	0
Marketable securities	97,060	135,105
Total financial assets	97,060	135,105
Level 2 [Member] | Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	0	0
Total financial liabilities	0	0
Level 2 [Member] | Cash [Member]
Assets
Cash and cash equivalents	0	0
Level 2 [Member] | Money market funds [Member]
Assets
Cash and cash equivalents	0	0
Level 2 [Member] | Commercial paper and corporate bonds [Member]
Assets
Marketable securities	86,416	124,498
Level 2 [Member] | U.S. government agency debt securities [Member]
Assets
Marketable securities	10,644	10,607
Level 3 [Member]
Assets
Cash and cash equivalents	0	0
Marketable securities	0	0
Total financial assets	0	0
Level 3 [Member] | Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	974	1,110
Total financial liabilities	974	1,110
Level 3 [Member] | Cash [Member]
Assets
Cash and cash equivalents	0	0
Level 3 [Member] | Money market funds [Member]
Assets
Cash and cash equivalents	0	0
Level 3 [Member] | Commercial paper and corporate bonds [Member]
Assets
Marketable securities	0	0
Level 3 [Member] | U.S. government agency debt securities [Member]
Assets
Marketable securities	$ 0	$ 0

Fair Value (Details 1)

Fair Value (Details 1) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent consideration, fair value - beginning of period	$ 1,110
Contingent consideration, earned by sellers	(297)
Contingent consideration, fair value adjustment	161
Contingent consideration, fair value - end of period	$ 974

Fair Value (Details Textual)

Fair Value (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers of financial assets between Level 1 and Level 2	$ 0	$ 0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value inputs and techniques	Investments in commercial paper, corporate bonds, and U.S. government agency debt securities have been classified as Level 2 as they are valued using quoted prices in less active markets or other directly or indirectly observable inputs. Fair values of corporate bonds and U.S. government agency debt securities were derived from a consensus or weighted-average price based on input of market prices from multiple sources at each reporting period. With regard to commercial paper, all of the securities had high credit ratings and one year or less to maturity; therefore, fair value was derived from accretion of purchase price to face value over the term of maturity or quoted market prices for similar instruments if available.
Level 3 [Member] | Contingent consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value inputs and techniques	Contingent consideration liabilities associated with earn-out payments related to the Company's February 2017 acquisition of CHITA Inc. ("CHITA") are classified as Level 3 in the fair value hierarchy because they rely significantly on inputs that are unobservable in the market. The fair value of portions of contingent consideration related to the achievement of a technical milestone have been estimated using situation-based modeling, which considers the probability-weighted present value of the expected payout amount. The fair value of portions of contingent consideration related to achievement of revenue targets have been estimated using a Monte Carlo simulation to simulate future performance of the acquired business under a risk-neutral framework; significant inputs to the simulation include a risk-adjusted discount rate of 10.2% and revenue volatility of 8.0%.

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Changes in the carrying amount of goodwill
Balance as of beginning of period	$ 216,017
Purchase price adjustment	(149)
Foreign currency translation adjustments	90
Balance as of end of period	$ 215,958

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets (Details 1) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Intangible assets
Gross carrying amount	$ 48,019	$ 47,385
Accumulated amortization	(19,743)	(17,839)
Net carrying amount	28,276	29,546
Developed technology [Member]
Intangible assets
Gross carrying amount	31,384	31,358
Accumulated amortization	(15,243)	(13,852)
Net carrying amount	16,141	17,506
Customer relationships [Member]
Intangible assets
Gross carrying amount	9,175	9,167
Accumulated amortization	(3,711)	(3,404)
Net carrying amount	5,464	5,763
Trade name [Member]
Intangible assets
Gross carrying amount	5,400	5,400
Accumulated amortization	(280)	(190)
Net carrying amount	5,120	5,210
Non-competition agreements [Member]
Intangible assets
Gross carrying amount	1,460	1,460
Accumulated amortization	(509)	(393)
Net carrying amount	951	1,067
Domain name [Member]
Intangible assets
Gross carrying amount	600	0
Accumulated amortization	0	0
Net carrying amount	$ 600	$ 0

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets (Details 2) $ in Thousands	Mar. 31, 2019USD ($)
Annual amortization for the next five years
Remainder of year current year	$ 5,603
Next twelve months	6,730
Year two	6,249
Year three	3,465
Year four	1,849
Year five	$ 3,780

Debt (Details)

Debt (Details) - Term loans (under credit facility) [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 21, 2017
Debt Instrument [Line Items]
Principal amount	$ 93,750	$ 95,000	$ 100,000
Unamortized debt issuance costs	(1,616)	(1,725)
Net carrying amount	$ 92,134	$ 93,275

Debt (Details 1)

Debt (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 109	$ 427
Credit facility [Member]
Debt Instrument [Line Items]
Contractual interest expense	854	748
Amortization of debt issuance costs	109	108
Unused commitment fee	147	200
Total interest expense	$ 1,110	$ 1,056
Term loans (under credit facility) [Member]
Debt Instrument [Line Items]
Interest rate during period	3.624%	3.229%
Revolver (under credit facility) [Member]
Debt Instrument [Line Items]
Unused commitment fee rate	0.15%	0.20%

Debt (Details Textual)

Debt (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 21, 2017
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 109	$ 427
Amortization of debt discount	$ 0	3,481
Credit facility [Member]
Debt Instrument [Line Items]
Approximate remaining life	45 months
Covenant compliance	The Company was in compliance with all financial covenants related to the Credit Facility
Total interest expense	$ 1,110	1,056
Contractual interest expense	854	748
Amortization of debt issuance costs	$ 109	$ 108
Term loans (under credit facility) [Member]
Debt Instrument [Line Items]
Maturity date description	The repayment terms of the Term Loans provide for monthly interest payments and quarterly principal payments, with a maturity date of December 2022.
Principal amount	$ 93,750		$ 95,000	$ 100,000
Current maturities of long-term debt	5,500		$ 4,900
Revolver (under credit facility) [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 400,000
Remaining borrowing capacity	$ 400,000
1.00% convertible senior notes [Member]
Debt Instrument [Line Items]
Contractual interest rate		1.00%
Maturity date description		settled on August 1, 2018
Total interest expense		$ 4,500
Contractual interest expense		700
Amortization of debt issuance costs		300
Amortization of debt discount		$ 3,500

Leases (Details)

Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Leases [Abstract]
Cash paid for operating leases	$ (3,858)
Right-of-use assets obtained in exchange for new operating leases	$ 0	[1]
[1]	No new operating leases were entered into during the three months ended March 31, 2019; all changes in operating lease liabilities during that period are the result of the Company's January 1, 2019 adoption of ASC 842.

Leases (Details 1)

Leases (Details 1) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
Operating lease liability maturities, remainder of fiscal year	$ 13,316
Year two	19,391
Year three	19,118
Year four	18,792
Year five	18,072
Thereafter	38,667
Total lease payments	127,356
Less imputed interest	(16,485)
Total present value of operating lease liabilities	$ 110,871

Leases (Details Textual)

Leases (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Leases [Abstract]
Description of operating leases	The Company leases office and data center space under operating lease agreements with remaining lease terms extending through 2031.
Operating lease expense	$ 4.8	$ 3.9
Short-term lease costs	$ 0.2
Weighted average remaining operating lease term	7 years 4 months 25 days
Weighted average discount rate	3.59%

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
[Line Items]
Total stock-based compensation	[1]	$ 19,730	$ 13,214
Stock options [Member]
[Line Items]
Total stock-based compensation		471	572
Restricted stock awards and units [Member]
[Line Items]
Total stock-based compensation		12,739	7,867
Performance-based restricted stock units [Member]
[Line Items]
Total stock-based compensation		4,735	3,227
Employee stock purchase plan [Member]
[Line Items]
Total stock-based compensation		$ 1,785	$ 1,548
[1]	Total stock-based compensation is presented in this table on a gross basis, consistent with the additional paid-in capital impact recorded in stockholders' equity. On the Company's consolidated statements of operations and consolidated statements of cash flows, stock-based compensation is presented net of foreign exchange impact and capitalization of eligible software development-related costs.

Stock-Based Compensation (Det_2

Stock-Based Compensation (Details 2) - Stock options [Member] $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)$ / sharesshares
Summary of activities and changes in stock option plans
Number of shares outstanding at beginning of period | shares	1,088
Weighted-average exercise price outstanding at beginning of period | $ / shares	$ 19.17
Number of shares granted | shares	0
Weighted-average exercise price granted | $ / shares	$ 0
Number of shares exercised | shares	(57)
Weighted-average exercise price exercised | $ / shares	$ 41.15
Number of shares forfeited | shares	0
Weighted-average exercise price forfeited | $ / shares	$ 0
Number of shares expired | shares	(1)
Weighted-average exercise price expired | $ / shares	$ 13.99
Number of shares outstanding at end of period | shares	1,030
Weighted-average exercise price outstanding at end of period | $ / shares	$ 17.96
Weighted average remaining contractual term outstanding at end of period	2 years 7 months 7 days
Aggregate intrinsic value outstanding at end of period | $	$ 57,037
Number of shares exercisable at end of period | shares	919
Weighted-average exercise price exercisable at end of period | $ / shares	$ 12.82
Weighted average remaining contractual term exercisable at end of period	1 year 11 months 12 days
Aggregate intrinsic value exercisable at end of period | $	$ 55,553
Number of shares vested and expected to vest at end of period | shares	1,025
Weighted-average exercise price vested and expected to vest at end of period | $ / shares	$ 17.71
Weighted average remaining contractual term vested and expected to vest at end of period	2 years 6 months 29 days
Aggregate intrinsic value vested and expected to vest at end of period | $	$ 56,992

Stock-Based Compensation (Det_3

Stock-Based Compensation (Details 3) - Restricted stock awards and units [Member] shares in Thousands	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Summary of time-based nonvested restricted stock awards and units
Nonvested number of shares/units at beggining of period | shares	1,936
Nonvested weighted-average grant-date fair value at beginning of period | $ / shares	$ 61.45
Granted number of shares | shares	909
Granted weighted-average grant-date fair value | $ / shares	$ 71.42
Vested number of shares/units | shares	(516)
Vested weighted-average grant-date fair value | $ / shares	$ 52.83
Forfeited number of shares/units | shares	(44)
Forfeited weighted-average grant-date fair value | $ / shares	$ 60.55
Nonvested number of shares/units at end of period | shares	2,285
Nonvested weighted-average grant-date fair value at end of period | $ / shares	$ 67.38

Stock-Based Compensation (Det_4

Stock-Based Compensation (Details 4) - Performance-based restricted stock units [Member] - Relative TSR [Member]	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Assumptions used to estimate fair value of TSR PBRSUs
Expected volatility - Medidata	35.00%	37.00%
Expected volatility - Comparison index	44.00%	42.00%
Expected term	2 years 10 months 16 days	2 years 10 months 10 days
Risk-free interest rate	2.47%	2.36%
Dividend yield	0.00%	0.00%

Stock-Based Compensation (Det_5

Stock-Based Compensation (Details 5) - Performance-based restricted stock units [Member] - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	1,026
Nonvested weighted-average grant-date fair value at beginning of period	$ 70.80
Granted number of units (based on performance at 100% of targeted levels)	310
Granted weighted-average grant-date fair value	$ 88.56
Adjustment due to expected performance	6
Adjustment due to expected performance weighted average grant date fair value	$ 104.54
Vested number of shares/units	(370)
Vested weighted-average grant-date fair value	$ 47.11
Forfeited number of shares/units	0
Forfeited weighted-average grant-date fair value	$ 77.64
Nonvested number of shares/units at end of period	972
Nonvested weighted-average grant-date fair value at end of period	$ 85.69
Net income growth [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	210
Granted number of units (based on performance at 100% of targeted levels)	0	117
Adjustment due to expected performance	0
Vested number of shares/units	0
Forfeited number of shares/units	0
Nonvested number of shares/units at end of period	210
Relative TSR [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	793
Granted number of units (based on performance at 100% of targeted levels)	155	116
Adjustment due to expected performance	6
Vested number of shares/units	(370)
Forfeited number of shares/units	0
Nonvested number of shares/units at end of period	584
Revenue [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	0
Granted number of units (based on performance at 100% of targeted levels)	155
Adjustment due to expected performance	0
Vested number of shares/units	0
Forfeited number of shares/units	0
Nonvested number of shares/units at end of period	155
Other individual and team goals [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	23
Granted number of units (based on performance at 100% of targeted levels)	0
Adjustment due to expected performance	0
Vested number of shares/units	0
Forfeited number of shares/units	0
Nonvested number of shares/units at end of period	23

Stock-Based Compensation (Det_6

Stock-Based Compensation (Details 6) - Employee stock purchase plan [Member]	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Weighted-average Black-Scholes assumptions used to estimate fair value of ESPP shares
Expected volatility	34.00%	37.00%
Expected term	1 year 6 months 16 days	1 year 8 months 7 days
Risk-free interest rate	2.39%	1.10%
Dividend yield	0.00%	0.00%

Stock-Based Compensation (Det_7

Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
[Line Items]
Incremental expense associated with equity modifications	$ 0.1	$ 0.2
Stock options [Member]
[Line Items]
Weighted-average grant-date fair value of stock options granted	$ 0	$ 0
Total intrinsic value of stock options exercised	$ 1.9	$ 7.6
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 2.5
Weighted-average remaining period over which cost is expected to be recognized	2 years 29 days
Restricted stock awards and units [Member]
[Line Items]
Total fair value of shares vested	$ 38.2	31.6
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 136.3
Weighted-average remaining period over which cost is expected to be recognized	2 years 9 months 16 days
Granted number of units (based on performance at 100% of targeted levels)	909
Performance-based restricted stock units [Member]
[Line Items]
Total fair value of shares vested	$ 26.6	$ 8.1
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 44.6
Weighted-average remaining period over which cost is expected to be recognized	1 year 11 months 7 days
Granted number of units (based on performance at 100% of targeted levels)	310
Employee stock purchase plan [Member]
[Line Items]
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 10.1
Weighted-average remaining period over which cost is expected to be recognized	1 year 5 months
Shares issued during period under employee stock purchase plan	0	0
Revenue [Member] | Performance-based restricted stock units [Member]
[Line Items]
Granted number of units (based on performance at 100% of targeted levels)	155
Award terms	performance conditions based on the compound annual growth rate of revenue over the three-year period ending December 31, 2021, vesting in full in three years with the number of shares ultimately earned ranging from zero to 250% of the target number of shares
Relative TSR [Member] | Performance-based restricted stock units [Member]
[Line Items]
Granted number of units (based on performance at 100% of targeted levels)	155	116
Award terms	market conditions based on the Company's total stockholder return ("TSR") relative to that of the Russell 2000 Index over the three-year period ending December 31, 2021, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares	market conditions based on the Company's TSR relative to that of the Russell 2000 Index over the three-year period ending December 31, 2020, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares
Net income growth [Member] | Performance-based restricted stock units [Member]
[Line Items]
Granted number of units (based on performance at 100% of targeted levels)	0	117
Award terms		performance conditions based on the compound annual growth rate of net income over the three-year period ending December 31, 2020, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares
Other individual and team goals [Member] | Performance-based restricted stock units [Member]
[Line Items]
Granted number of units (based on performance at 100% of targeted levels)	0

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reconciliation of the numerators and denominators of basic and diluted earnings per share
Net income	$ 11,145	$ 10,325
Denominator for basic earnings per share:
Weighted average common shares outstanding	59,693	57,055
Dilutive potential common shares:
Stock options	775	922
Restricted stock awards and units	676	743
Performance-based restricted stock units	558	494
Employee stock purchase plan	53	250
Convertible senior notes	0	634
Weighted average common shares outstanding with assumed conversion	61,755	60,098
Basic earnings per share	$ 0.19	$ 0.18
Diluted earnings per share	$ 0.18	$ 0.17

Earnings Per Share (Details 1)

Earnings Per Share (Details 1) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive common stock equivalents excluded from the calculation of diluted earnings per share
Antidilutive shares excluded from calculation of diluted earnings (loss) per share	774	599
Stock options [Member]
Antidilutive common stock equivalents excluded from the calculation of diluted earnings per share
Antidilutive shares excluded from calculation of diluted earnings (loss) per share	81	94
Restricted stock awards and units [Member]
Antidilutive common stock equivalents excluded from the calculation of diluted earnings per share
Antidilutive shares excluded from calculation of diluted earnings (loss) per share	28	263
Performance-based restricted stock units [Member]
Antidilutive common stock equivalents excluded from the calculation of diluted earnings per share
Antidilutive shares excluded from calculation of diluted earnings (loss) per share	84	54
Employee stock purchase plan [Member]
Antidilutive common stock equivalents excluded from the calculation of diluted earnings per share
Antidilutive shares excluded from calculation of diluted earnings (loss) per share	581	188

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits	$ 6.4	$ 6.4
Changes in tax position	$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details)	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Legal matters	The Company is subject to legal proceedings and claims that arise in the ordinary course of business and records an estimated liability for these matters when an adverse outcome is considered to be probable and can be reasonably estimated. Although the outcome of the litigation cannot be predicted with certainty and some lawsuits, claims, or proceedings may be disposed of unfavorably to the Company, which could materially and adversely affect its financial condition or results of operations, the Company does not believe that it is currently a party to any material legal proceedings.
Standard product warranty description	The Company typically provides contractual warranties to its customers covering its solutions and services. To date, any refunds provided to customers have been immaterial.
Description of executive change in control agreements	The Company has change in control agreements with its chief executive officer and certain other executive officers. These agreements provide for payments to be made to such officers upon involuntary termination of their employment by the Company without cause or by such officers for good reason as defined in the agreements, within a period of 2 years following a change in control. The agreements provide that, upon a qualifying termination event, such officers will be entitled to (a) a severance payment equal to the sum of the officer’s base salary and target bonus amount (except that such payment for the Company's chief executive officer and president would be two times such sum); (b) continuation of health benefits for one year (except that such continuation for the Company's chief executive officer and president would be for two years); and (c) immediate vesting of remaining unvested equity awards, unless otherwise specified in the equity award agreements.