Medidata Solutions 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 30, 2018
Document and Entity Information [Abstract]
Entity registrant name	Medidata Solutions, Inc.
Entity central index key	1,453,814
Document type	10-Q
Amendment flag	false
Document period end date	Jun. 30, 2018
Document fiscal period focus	Q2
Document fiscal year focus	2,018
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Entity common stock, shares outstanding		59,676,491

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 120,298	$ 237,325
Marketable securities	287,603	246,967
Accounts receivable, net of allowance for doubtful accounts	137,169	110,685
Prepaid commission expense	17,612	12,404
Prepaid expenses and other current assets	37,109	33,636
Total current assets	599,791	641,017
Restricted cash	5,523	5,518
Furniture, fixtures and equipment, net	93,088	88,091
Marketable securities- long-term	69,476	179,041
Goodwill	198,780	47,435
Intangible assets, net	54,938	17,587
Deferred income taxes- long-term	37,414	35,789
Other assets	43,775	46,755
Total assets	1,102,785	1,061,233
Current liabilities:
Accounts payable	6,527	5,009
Accrued payroll and other compensation	23,061	32,537
Accrued expenses and other	37,624	36,041
Deferred revenue	72,075	77,375
1.00% convertible senior notes, net	285,748	278,094
Total current liabilities	425,035	429,056
Noncurrent liabilities:
Term loans, net	91,906	92,841
Deferred revenue, less current portion	3,993	5,256
Deferred tax liabilities	100	99
Other long-term liabilities	20,395	21,371
Total noncurrent liabilities	116,394	119,567
Total liabilities	541,429	548,623
Commitments and contingencies
Stockholders' equity:
Preferred stock	0	0
Common stock	643	628
Additional paid-in capital	527,336	486,147
Treasury stock	(150,964)	(132,705)
Accumulated other comprehensive loss	(4,490)	(3,377)
Retained earnings	188,831	161,917
Total stockholders' equity	561,356	512,610
Total liabilities and stockholders' equity	$ 1,102,785	$ 1,061,233

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Accounts receivable, allowance for doubtful accounts	$ 1,668	$ 1,454
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	64,289	62,801
Common stock, shares outstanding	59,634	58,607
Treasury stock, shares	4,655	4,194

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Revenues
Subscription		$ 130,486	$ 112,904	[1]	$ 257,305	$ 220,797	[1]
Professional services		25,419	23,123		47,798	42,874
Total revenues		155,905	136,027		305,103	263,671
Cost of revenues
Subscription		21,602	17,017		41,943	34,146
Professional services		15,899	14,903		31,860	28,388
Total cost of revenues	[2],[3]	37,501	31,920		73,803	62,534
Gross profit		118,404	104,107		231,300	201,137
Operating costs and expenses:
Research and development	[3]	40,789	35,884		78,311	65,821
Sales and marketing	[2],[3]	37,106	32,479	[1]	73,967	62,705	[1]
General and administrative	[3]	27,672	23,083		52,859	47,071
Total operating costs and expenses		105,567	91,446		205,137	175,597
Operating income		12,837	12,661		26,163	25,540
Interest and other income (expense):
Interest expense		(5,700)	(4,383)		(11,275)	(8,710)
Interest income		2,328	1,328		4,416	2,499
Other income (expense), net		7,729	0		7,633	0
Total interest and other expense, net		4,357	(3,055)		774	(6,211)
Income before income taxes		17,194	9,606		26,937	19,329
Provision for income taxes		605	2,065	[1]	23	1,808	[1]
Net income		$ 16,589	$ 7,541	[1],[4]	$ 26,914	$ 17,521	[1],[4]
Earnings per share:
Basic		$ 0.29	$ 0.13	[1]	$ 0.47	$ 0.31	[1]
Diluted		$ 0.27	$ 0.13	[1]	$ 0.44	$ 0.30	[1]
Weighted average common shares outstanding:
Basic		57,448	56,433		57,252	56,254
Diluted		60,874	59,835		60,564	59,051
Total stock-based compensation	[3]	$ 15,119	$ 12,692		$ 28,274	$ 23,013
Total amortization of intangible assets	[2]	1,436	1,141		2,650	1,678
Cost of revenues
Weighted average common shares outstanding:
Total stock-based compensation	[3]	1,506	1,246		2,774	2,415
Total amortization of intangible assets	[2]	1,205	1,022		2,299	1,476
Research and development
Weighted average common shares outstanding:
Total stock-based compensation	[3]	3,319	3,427		6,173	6,262
Sales and marketing
Weighted average common shares outstanding:
Total stock-based compensation	[3]	2,917	1,836		5,561	3,011
Total amortization of intangible assets	[2]	231	119		351	202
General and administrative
Weighted average common shares outstanding:
Total stock-based compensation	[3]	$ 7,377	$ 6,183		$ 13,766	$ 11,325
[1]	The condensed consolidated statements of operations for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."
[2]	Amortization of intangible assets included in cost of revenues and operating costs and expenses
[3]	Stock-based compensation expense included in cost of revenues and operating costs and expenses
[4]	The condensed consolidated statements of comprehensive income for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Net income	$ 16,589	$ 7,541	[1],[2]	$ 26,914	$ 17,521	[1],[2]
Other comprehensive income (loss):
Foreign currency translation adjustments	(1,954)	879		(684)	1,302
Unrealized gain (loss) on marketable securities	719	128		(307)	240
Other comprehensive income (loss)	(1,235)	1,007		(991)	1,542
Income tax effect of unrealized gain or loss on marketable securities	(180)	(49)		(122)	(92)
Other comprehensive income (loss), net of tax	(1,415)	958		(1,113)	1,450
Comprehensive income (loss), net of tax	$ 15,174	$ 8,499	[1]	$ 25,801	$ 18,971	[1]
[1]	The condensed consolidated statements of comprehensive income for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."
[2]	The condensed consolidated statements of operations for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income		$ 26,914	$ 17,521	[1],[2]
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of intangible assets and depreciation		16,218	10,065
Stock-based compensation	[3]	28,274	23,013
Amortization of discounts or premiums on marketable securities		50	757
Deferred income taxes		106	2,406	[4]
Amortization of debt issuance costs		856	639
Amortization of debt discount		7,015	6,607
Provision for doubtful accounts		763	526
Loss on fixed asset disposal		127	(2)
Gain on step acquisition		(7,648)	0
Changes in fair value of contingent consideration		7	58
Changes in operating assets and liabilities:
Accounts receivable		(27,247)	4,058
Prepaid commission expense		(7,205)	(5,514)	[4]
Prepaid expenses and other current assets		(3,008)	(12,366)	[4]
Other assets		1,591	1,171
Accounts payable		1,753	4,490
Accrued payroll and other compensation		(8,909)	(10,122)
Accrued expenses and other		3,236	5,313
Deferred revenue		(9,572)	11,198	[4]
Other long-term liabilities		455	884
Net cash provided by (used in) operating activities		23,776	60,702
Cash flows from investing activities:
Purchases of furniture, fixtures and equipment		(19,520)	(16,642)
Purchases of available-for-sale securities		(69,214)	(157,228)
Proceeds from sale of available-for-sale securities		137,786	154,117
Acquisition of business, net of cash acquired		(178,568)	(22,941)
Net cash provided by (used in) investing activities		(129,516)	(42,694)
Cash flows from financing activities:
Proceeds from exercise of stock options		6,351	9,057
Proceeds from employee stock purchase plan		6,345	4,248
Acquisition of treasury stock		(18,257)	(14,785)
Term loan principal payments		(1,250)	0
Payment of acquisition-related earn-out		(4,087)	0
Payments of credit facility financing costs		(175)	0
Net cash provided by (used in) financing activities		(11,073)	(1,480)
Effect of exchange rate changes on cash, cash equivalents and restricted cash		(209)	414
Net increase (decrease) in cash, cash equivalents and restricted cash		(117,022)	16,942
Cash, cash equivalents and restricted cash - beginning of period		242,843	99,279
Cash, cash equivalents and restricted cash - end of period		125,821	116,221
Cash paid during the period for:
Interest		3,263	1,441
Income taxes		2,253	2,877
Noncash activities:
Furniture, fixtures, and equipment acquired but not yet paid for at period-end		3,054	4,671
Contingent consideration associated with acquisition		$ 0	$ 5,697
[1]	The condensed consolidated statements of comprehensive income for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."
[2]	The condensed consolidated statements of operations for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."
[3]	Stock-based compensation expense included in cost of revenues and operating costs and expenses
[4]	The condensed consolidated statement of cash flows for the six months ended June 30, 2017 has been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 are the same as those at December 31, 2017 , which are included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2017 , filed with the Securities and Exchange Commission (“SEC”) on February 28, 2018 . Basis of Presentation — The accompanying interim condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017 , the condensed consolidated statements of operations for the three and six months ended June 30, 2018 and 2017 , the condensed consolidated statements of comprehensive income for the three and six months ended June 30, 2018 and 2017 , and the condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 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, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2018 . 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 June 30, 2018 , results of its operations for the three and six months ended June 30, 2018 and 2017 , comprehensive income for the three and six months ended June 30, 2018 and 2017 , and cash flows for the six months ended June 30, 2018 and 2017 . The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 . 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 June 30, 2018 and December 31, 2017 , unbilled accounts receivable of $11.8 million and $12.5 million , respectively, were included in accounts receivable on the Company's condensed consolidated balance sheets. In general, there is a direct relationship between the Company's accounts receivable balance and its transaction volume. Revenue Recognition — Revenues are recognized when control of the promised goods or services are transferred to a customer, in an amount that reflects the consideration that the Company expects to receive in exchange for those goods or services. The Company derives its revenues from two sources: (1) subscription revenues, which are comprised of subscription fees from customers utilizing the Company's cloud-based solutions; and (2) professional services, such as training, implementation, consulting, interface creation, trial configuration, data testing, reporting, procedure documentation, and other customer-specific services. The Company applies the following five steps in order to determine the appropriate amount of revenue to be recognized as it fulfills its obligations under each of its agreements: • identify the contract with a customer; • identify the performance obligations in the contract; • determine the transaction price; • allocate the transaction price to performance obligations in the contract; and • recognize revenue as the performance obligation is satisfied. For further information, see Note 2 , “Revenues,” to the condensed consolidated financial statements included in this Quarterly Report on Form 10-Q. Subscription The Company derives its subscription revenues from multi-study and single-study arrangements that grant the customer the right to utilize its cloud-based solutions for a specified term. Multi-study arrangements grant the customer the right to manage a predetermined number of clinical trials simultaneously for a term typically ranging from one to five years. Single-study arrangements allow customers to use the Company’s solutions on a per-trial basis. Subscription services are transferred to customers over time. The Company uses the passage of time as its measurement method, as control of the services is simultaneously transferred to and used by the customer throughout the contractual term. As a result, revenue for subscription services is recognized ratably over the term of the agreement, which is generally aligned with the dates during which the customer has access to the Company’s cloud-based applications. Fees for subscription services are generally invoiced in advance installments and typically have payment terms of net 30 or net 45 days. Professional Services The Company also makes available a range of professional services, including implementation, enablement, training, and strategic consulting. Professional services do not result in significant alterations to the underlying solutions. Professional services engagements involving implementation and training tend to be shorter term in nature (expected durations of less than one year), while enablement and consulting type engagements are longer in term (expected durations of one to five years). Professional services are transferred to customers over time. For fixed price arrangements, the Company measures its progress in transferring services to a customer using a proportional performance method. The proportional performance method is reflective of the variable rates at which services are transferred to the customer, and results in recognition of revenue that is consistent with the services provided to date. For time and materials contracts, the Company recognizes revenue as services are rendered. Fees for professional services are generally invoiced either in milestone installments based on work performed or, for time and materials based arrangements, as services are rendered, and typically have payment terms of net 30 or net 45 days. Performance Obligations The Company enters into contracts that contain multiple distinct performance obligations, combining a cloud-based technology subscription with various professional services. The Company has determined that its subscriptions and professional services are distinct performance obligations because both can be and are sold by the Company on a standalone basis, and because other vendors sell similar technologies and services on a standalone basis. For each performance obligation identified, the Company estimates the standalone selling price, which represents the price at which the Company would sell the good or service separately. If the standalone selling price is not observable through past transactions, the Company estimates the standalone selling price, taking into account available information such as market conditions, review of historical pricing data, and internal pricing guidelines related to the performance obligations. The Company then allocates the transaction price among those obligations based on the estimation of standalone selling price. Transaction prices for the Company's contracts may include both fixed and variable consideration, but do not contain significant financing components or noncash consideration. Cost to Obtain and Fulfill a Contract The Company capitalizes commission expenses paid to internal sales personnel that are incremental to obtaining customer contracts. Costs related to nonrenewable contracts are deferred and amortized on a straight-line basis over the duration of the contractual term. Costs related to renewable contracts are deferred and amortized on a straight-line basis over a period equal to twice the contractual term, which the Company deems to be the expected period of benefit for these costs. In developing this estimate, the Company considered its historical renewal rates and customer retention rates, as well as technology development life cycles and other industry factors. The Company defers these costs in prepaid commission expense and other current assets, net of any long term portion included in other noncurrent assets in the Company's condensed consolidated balance sheets. These costs are periodically reviewed for impairment. 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 May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers , which supersedes the existing accounting standards for revenue recognition in Accounting Standards Codification ("ASC") 605, and provides principles for recognizing revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. ASU No. 2014-09 also creates a new subtopic under ASC 340, Other Assets and Deferred Costs , which discusses the deferral of incremental costs of obtaining a contract with a customer, including the period of amortization of such costs. The Company adopted ASU No. 2014-09 on January 1, 2018, using the full retrospective method. Refer to Note 2 , "Revenues," for related disclosures. The following tables summarize the impact of adoption of ASC 606 on the Company’s condensed consolidated statements of operations for the three and six months ended June 30, 2017 (in thousands, except per share data): Three Months Ended June 30, 2017 Six Months Ended June 30, 2017 As Reported Under ASC 605 Impact of ASC 606 Adoption As Adjusted As Reported Under ASC 605 Impact of ASC 606 Adoption As Adjusted Revenues Subscription $ 114,291 $ (1,387 ) $ 112,904 $ 221,361 $ (564 ) $ 220,797 Professional services 23,123 — 23,123 42,874 — 42,874 Total revenues 137,414 (1,387 ) 136,027 264,235 (564 ) 263,671 Operating costs and expenses Sales and marketing 32,784 (305 ) 32,479 62,893 (188 ) 62,705 Operating income 13,743 (1,082 ) 12,661 25,916 (376 ) 25,540 Provision for income taxes 2,438 (373 ) 2,065 1,937 (129 ) 1,808 Net income $ 8,250 $ (709 ) $ 7,541 $ 17,768 $ (247 ) $ 17,521 Earnings per share Basic $ 0.15 $ (0.02 ) $ 0.13 $ 0.32 $ (0.01 ) $ 0.31 Diluted $ 0.14 $ (0.01 ) $ 0.13 $ 0.30 $ — $ 0.30 The adoption has no cash flow impact. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , which amends certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. ASU No. 2016-01 is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual periods. The Company adopted ASU No. 2016-01 on January 1, 2018, and the adoption did not have a material impact on its condensed consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Cash Flows - Classification of Certain Cash Receipts and Cash Payments , which addresses the diversity in practice around presentation of certain cash receipts and payments in the statement of cash flows. ASU No. 2016-15 is effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The Company adopted ASU No. 2016-15 on January 1, 2018, and the adoption did not have a material impact on its condensed consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business , which provides a more specific definition of a business than was afforded under previous guidance. The definition of a business affects many areas of accounting, including acquisitions, disposals, goodwill, and consolidation. ASU No. 2017-01 is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. The Company adopted ASU No. 2017-01 on January 1, 2018, and the adoption had no impact on its condensed consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting , which clarifies when a change in the terms or conditions of a share-based payment award should be accounted for as a modification. ASU No. 2017-09 is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. The Company adopted ASU No. 2017-09 on January 1, 2018, and the adoption did not have a material impact on its condensed consolidated financial statements. In June 2018. the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which simplifies several aspects of the accounting for nonemployee share-based payment transactions by expanding the scope of the stock-based compensation guidance in ASC 718 to include share-based payment transactions for acquiring goods and services from non-employees. ASU No. 2018-07 is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods. Early adoption is permitted, but entities may not adopt prior to adopting the new revenue recognition guidance in ASC 606. The Company early adopted ASU No. 2018-07 in the second quarter of 2018, and the adoption did not have a material impact on its 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, except as described below. In February 2016, the FASB issued 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 new guidance also adds quantitative and qualitative disclosure requirements around leasing activities. ASU No. 2016-02 is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods. The Company will adopt ASU No. 2016-02 on January 1, 2019. The Company expects that this standard will have a material effect on its financial condition, with the most significant change relating to the recognition of new right-of-use assets and lease liabilities on its consolidated balance sheets for its facility operating leases. The Company estimates that the hypothetical balance sheet impact of recognizing these assets and liabilities would be approximately 5% of total assets and 10% of total liabilities as of June 30, 2018 , based on the present value of the remaining minimum rental payments under current leasing standards for existing operating leases. The final quantitative impact of the adoption of the new lease guidance is subject to change from these estimates, pending the completion of the Company's implementation in the first quarter of 2019. 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 will adopt ASU No. 2018-02 on January 1, 2019, and does not expect the adoption to have a material impact on its condensed consolidated financial statements.

Revenues

Revenues	6 Months Ended
	Jun. 30, 2018
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 and six months ended June 30, 2018 and 2017 (in thousands): Three Months Ended June 30, 2018 2017 Subscription Professional Services Total Subscription Professional Services Total Revenues: United States $ 99,646 $ 18,526 $ 118,172 $ 85,425 $ 16,708 $ 102,133 Rest of Americas 1,689 277 1,966 57 196 253 Total Americas 101,335 18,803 120,138 85,482 16,904 102,386 Japan 7,665 1,261 8,926 7,627 1,222 8,849 Rest of Asia Pacific 3,875 1,243 5,118 2,603 1,351 3,954 Total Asia Pacific 11,540 2,504 14,044 10,230 2,573 12,803 Europe, Middle East and Africa 17,611 4,112 21,723 17,192 3,646 20,838 Total $ 130,486 $ 25,419 $ 155,905 $ 112,904 $ 23,123 $ 136,027 Six Months Ended June 30, 2018 2017 Subscription Professional Services Total Subscription Professional Services Total Revenues: United States $ 195,811 $ 34,510 $ 230,321 $ 169,764 $ 30,616 $ 200,380 Rest of Americas 1,998 481 2,479 87 221 308 Total Americas 197,809 34,991 232,800 169,851 30,837 200,688 Japan 15,777 3,055 18,832 14,276 3,029 17,305 Rest of Asia Pacific 7,576 2,381 9,957 4,952 2,297 7,249 Total Asia Pacific 23,353 5,436 28,789 19,228 5,326 24,554 Europe, Middle East and Africa 36,143 7,371 43,514 31,718 6,711 38,429 Total $ 257,305 $ 47,798 $ 305,103 $ 220,797 $ 42,874 $ 263,671 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 six months ended June 30, 2018 and 2017 (in thousands): Deferred Revenue 2018 2017 Balance as of January 1 $ 82,631 $ 75,850 Revenue recognized that was included in deferred revenue at the beginning of the period (71,137 ) (64,581 ) Revenue recognized that was not included in deferred revenue at the beginning of the period (233,400 ) (198,379 ) Increases due to invoicing 297,161 277,087 Other 813 (2,705 ) Balance as of June 30 $ 76,068 $ 87,272 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 June 30, 2018 , 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, which the Company also refers to as total multi-year subscription backlog, is approximately $1 billion , representing the future contract value of outstanding multi-study and single study arrangements, billed and unbilled as of June 30, 2018 . Of this amount, approximately $257 million , $371 million , and $389 million are expected to be recognized in 2018 , 2019 , and thereafter, respectively. As of June 30, 2018 , 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 $44.4 million and $36.9 million as of June 30, 2018 and December 31, 2017 , respectively. Amortization of capitalized contract costs was $4.6 million and $5.7 million for the three months ended June 30, 2018 and 2017 , respectively, and $9.5 million and $12.1 million for the six months ended June 30, 2018 and 2017 , respectively. There have been no impairment losses related to capitalized contract costs.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2018
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 six months ended June 30, 2018 and 2017 , the Company withheld 271,585 shares at an average price of $67.23 and 260,737 shares at an average price of $56.71 , 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 six months ended June 30, 2018 and 2017 , 189,668 and 154,106 forfeited shares, respectively, were transferred to treasury stock at their par value of $0.01.

Investments

Investments	6 Months Ended
	Jun. 30, 2018
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 June 30, 2018 and December 31, 2017 (in thousands): As of June 30, 2018 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 333,185 $ — $ (1,650 ) $ 331,535 U.S. government agency debt securities 25,690 — (146 ) 25,544 Total $ 358,875 $ — $ (1,796 ) $ 357,079 As of December 31, 2017 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 392,481 $ — $ (1,334 ) $ 391,147 U.S. government agency debt securities 35,016 — (155 ) 34,861 Total $ 427,497 $ — $ (1,489 ) $ 426,008 Contractual maturities of the Company’s marketable securities as of June 30, 2018 and December 31, 2017 are summarized as follows (in thousands): As of June 30, 2018 As of December 31, 2017 Cost Estimated Fair Value Cost Estimated Fair Value Due in one year or less $ 288,628 $ 287,603 $ 247,495 $ 246,967 Due in one to five years 70,247 69,476 180,002 179,041 Total $ 358,875 $ 357,079 $ 427,497 $ 426,008 At June 30, 2018 , the Company had $1.8 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 June 30, 2018 are temporary in nature. Accordingly, the Company did not consider its investments in marketable securities to be other-than-temporarily impaired as of June 30, 2018 . The following tables provide the fair market value and gross unrealized losses of the Company's marketable securities with unrealized losses, aggregated by security type, as of June 30, 2018 and December 31, 2017 (in thousands): In Loss Position for Less than 12 Months As of June 30, 2018 As of December 31, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 254,385 $ (1,353 ) $ 295,224 $ (1,137 ) U.S. government agency debt securities 10,575 (116 ) 18,431 (86 ) Total $ 264,960 $ (1,469 ) $ 313,655 $ (1,223 ) In Loss Position for More than 12 Months As of June 30, 2018 As of December 31, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 77,151 $ (297 ) $ 95,923 $ (197 ) U.S. government agency debt securities 14,970 (30 ) 16,430 (69 ) Total $ 92,121 $ (327 ) $ 112,353 $ (266 ) During the three and six months ended June 30, 2018 and 2017 , the Company recorded an insignificant amount of net realized gains from the sale of marketable securities. Other Investments The Company holds shares of Series D Preferred Stock of Syapse Inc. ("Syapse") 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 June 30, 2018 and December 31, 2017 . The Company periodically evaluates this investment to determine if impairment charges are required; no impairment charges were recognized during the three and six months ended June 30, 2018 . As of December 31, 2017 , the Company held shares of Series Seed Preferred Stock and Series B Preferred Stock of SHYFT Analytics, Inc. ("SHYFT"), purchased in private placements. These investments did not have a readily determinable fair value and were carried at original cost of $5.1 million in other assets on the Company's condensed consolidated balance sheets. In June 2018, the Company acquired SHYFT and realized a gain on step acquisition of $7.6 million based upon the implied fair value of its previous holdings relative to the enterprise value for the transaction. This gain is included in other income, net on the Company's condensed consolidated statements of operations for the three and six months ended June 30, 2018 . Refer to Note 6 , "Acquisitions," for further discussion of the Company's acquisition of SHYFT.

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUE The following table summarizes, as of June 30, 2018 and December 31, 2017 , 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, 2017 (in thousands): As of June 30, 2018 As of December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 118,584 $ — $ — $ 118,584 $ 237,149 $ — $ — $ 237,149 Money market funds 1,714 — — 1,714 176 — — 176 Total cash and cash equivalents 120,298 — — 120,298 237,325 — — 237,325 Commercial paper and corporate bonds — 331,534 — 331,534 — 391,147 — 391,147 U.S. government agency debt securities — 25,545 — 25,545 — 34,861 — 34,861 Total marketable securities — 357,079 — 357,079 — 426,008 — 426,008 Total financial assets measured at fair value on a recurring basis $ 120,298 $ 357,079 $ — $ 477,377 $ 237,325 $ 426,008 $ — $ 663,333 Contingent consideration – short-term $ — $ — $ 1,351 $ 1,351 $ — $ — $ 3,993 $ 3,993 Contingent consideration – long-term — — 581 581 — — 2,012 2,012 Total financial liabilities measured at fair value on a recurring basis $ — $ — $ 1,932 $ 1,932 $ — $ — $ 6,005 $ 6,005 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 six months ended June 30, 2018 and 2017 , 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%. Short-term and long-term portions of contingent consideration are recorded in accrued expenses and other and other long-term liabilities, respectively, 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 financial liabilities during the six months ended June 30, 2018 (in thousands): Balance as of January 1, 2018 $ 6,005 Amounts earned by sellers (4,080 ) Fair value adjustment (included in general and administrative expenses) 7 Balance as of June 30, 2018 $ 1,932 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.

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
ACQUISITION	ACQUISITIONS Three and Six Months Ended June 30, 2018 On June 20, 2018 , the Company acquired all outstanding equity interests in SHYFT , a Waltham, Massachusetts provider of cloud data analytics for life sciences . With this acquisition, the Company expands its offerings to include commercial and real-world data analytics solutions that are designed specifically for the pharmaceutical and biotech industries . The total purchase price of $196.5 million was composed of cash consideration of $183.8 million and the Company's previous investment in SHYFT, which had a fair value of $12.7 million as of the acquisition date. (Refer to Note 4 , "Investments — Other Investments" for further information on the initial investment and gain recognized on step acquisition.) In connection with this acquisition, the Company acquired $4.7 million in cash and cash equivalents, assumed $1.9 million in net tangible liabilities, and recognized a deferred tax asset of $1.9 million ; given the transaction's proximity to the end of the current reporting period, valuation of identified intangible assets is still in progress and allocation of the remaining $191.8 million of purchase price between intangible assets and goodwill is incomplete. The Company anticipates that this transaction will generate significant goodwill due to the skilled workforce of approximately 150 employees acquired and considerable synergies expected. As of June 30, 2018, the Company has recorded a provisional estimate based on observation of industry trends , consisting of $40.0 million of intangible assets and $151.8 million of goodwill. The Company expects to finalize valuation and useful life determination for the acquired customer relationships, developed technology, non-competition agreements, and trade name during the third quarter of 2018. The purchase price and the allocation thereof are subject to change within the relevant one-year measurement period as a result of customary working capital adjustments. The Company's consolidated results of operations for the three and six months ended June 30, 2018 include the revenues and expenses of SHYFT since the date of acquisition. The Company does not consider this acquisition to be significant to its results of operations; as such, pro forma revenue and earnings information is not provided. Three and Six Months Ended June 30, 2017 The Company acquired all outstanding equity interests in CHITA and Mytrus , Incorporated ("Mytrus") on February 17, 2017 and April 18, 2017 , respectively, adding regulated document and standard operating procedure ("SOP") management, electronic trial master file ("eTMF"), and eConsent capabilities to its platform . Aggregate purchase consideration of $28.9 million consisted of upfront consideration of $23.2 million and contingent consideration (associated with CHITA) initially valued at $5.7 million .

Goodwill and Intangible Assets

Goodwill and Intangible Assets	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS The change in the carrying amount of goodwill during the six months ended June 30, 2018 was as follows (in thousands): Balance as of January 1, 2018 $ 47,435 Additions related to current period acquisition - SHYFT 151,857 Final purchase price adjustment - Mytrus (422 ) Foreign currency translation adjustments (90 ) Balance as of June 30, 2018 $ 198,780 Total intangible assets are summarized as follows (in thousands): As of June 30, 2018 As of December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 44,407 $ (11,152 ) $ 33,255 $ 24,436 $ (8,883 ) $ 15,553 Customer relationships 24,481 (2,907 ) 21,574 4,489 (2,595 ) 1,894 Non-competition agreements 260 (151 ) 109 260 (120 ) 140 Total $ 69,148 $ (14,210 ) $ 54,938 $ 29,185 $ (11,598 ) $ 17,587 Future amortization of intangible assets is expected to be as follows (in thousands): Remainder of 2018 $ 6,339 2019 12,486 2020 11,742 2021 11,472 2022 8,877 2023 4,022 Thereafter — Total $ 54,938

Debt

Debt	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
DEBT	DEBT 1.00% Convertible Senior Notes The Company's 1.00% convertible senior notes (the "Notes"), issued in August 2013, consisted of the following components as of June 30, 2018 and December 31, 2017 (in thousands): June 30, December 31, Equity component, net of equity issue costs $ 60,222 $ 60,222 Liability component: Principal 287,500 287,500 Less: unamortized debt discount (1,646 ) (8,661 ) Less: unamortized debt issuance costs (106 ) (745 ) Net carrying amount $ 285,748 $ 278,094 As of June 30, 2018 and December 31, 2017 , the estimated fair value of the Notes was $395.7 million and $336.4 million , respectively. The Company considers this disclosure to be a Level 2 measurement because it is based upon a recent modeled bid-price quote for the Notes, reflecting activity in a less active market. The Notes mature on August 1, 2018 unless earlier repurchased or converted. Until close of business on the business day immediately preceding the maturity date, holders may convert their Notes at any time; as such, the Notes are convertible as of June 30, 2018 . Based on the closing price of the Company's common stock as of June 30, 2018 of $80.56 , the if-converted value of the Notes exceeded their face value by $111.5 million . Upon conversion, the Company has elected to pay cash for the principal amount of the Notes and to deliver shares of common stock for any amounts in excess of principal. As of June 30, 2018 , the remaining life of the Notes is approximately 1 month , and the Notes are classified as current liabilities on the Company's condensed consolidated balance sheet. The following table sets forth total interest expense recognized related to the Notes for the three and six months ended June 30, 2018 and 2017 (in thousands except percentages): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Contractual interest expense $ 719 $ 719 $ 1,438 $ 1,438 Amortization of debt issuance costs 320 320 639 639 Amortization of debt discount 3,534 3,328 7,015 6,607 Total $ 4,573 $ 4,367 $ 9,092 $ 8,684 Effective interest rate 6.5 % 6.5 % 6.5 % 6.5 % 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 June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Term Loans $ 98,750 $ 100,000 Less: unamortized debt issuance costs (1,942 ) (2,159 ) Net carrying amount (1) $ 96,808 $ 97,841 (1) Of the total carrying amount of the Term Loans, short-term maturities of $4.9 million and $5.0 million were included in accrued expenses and other on the Company's condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017, respectively. As of June 30, 2018 , the contractual interest rate on the Term Loans was 3.465% , and there was a 0.200% commitment fee on the undrawn Revolver. The following table sets forth total interest expense recognized related to the Credit Facility for the three and six months ended June 30, 2018 (in thousands): Three Months Ended Six Months Ended June 30, 2018 Contractual interest expense on Term Loans $ 811 $ 1,559 Amortization of debt issuance costs 109 217 Unused commitment fee on Revolver 209 409 Total $ 1,129 $ 2,185 As of June 30, 2018 the remaining term of the Credit Facility is approximately 54 months . The Company was in compliance with all financial covenants related to the Credit Facility as of June 30, 2018 .

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION For the three and six months ended June 30, 2018 and 2017 , the components of stock-based compensation expense were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Stock options $ 522 $ 938 $ 1,094 $ 1,855 Restricted stock awards and units 9,024 7,769 16,891 14,688 Performance-based restricted stock units 3,932 3,074 7,159 4,702 Employee stock purchase plan 1,712 969 3,260 1,897 Total stock-based compensation (1) $ 15,190 $ 12,750 $ 28,404 $ 23,142 (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 fair value of each stock option granted during the three and six months ended June 30, 2018 and 2017 was estimated on the date of grant using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility 42 % 43 % 42 % 44 % Expected life 4.78 years 6.00 years 4.78 years 6.00 years Risk-free interest rate 2.82 % 2.02 % 2.82 % 2.07 % Dividend yield — — — — The following table summarizes the status of the Company's stock options as of June 30, 2018 , and changes during the six 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, 2018 1,511 $22.72 Granted 35 72.27 Exercised (248 ) 25.62 Forfeited (34 ) 45.55 Expired — — Outstanding at June 30, 2018 1,264 $22.91 3.88 $72,894 Exercisable at June 30, 2018 1,092 $17.45 3.16 $68,942 Vested and expected to vest at June 30, 2018 1,252 $22.52 3.83 $72,657 The weighted-average grant-date fair value of stock options granted during the three months ended June 30, 2018 and 2017 was $28.93 and $25.47 , respectively. The weighted-average grant-date fair value of stock options granted during the six months ended June 30, 2018 and 2017 was $28.93 and $25.37 , respectively. The total intrinsic value of stock options exercised during the three months ended June 30, 2018 and 2017 was $3.8 million and $4.0 million , respectively. The total intrinsic value of stock options exercised during the six months ended June 30, 2018 and 2017 was $11.4 million and $8.0 million , respectively. As of June 30, 2018 , there was $3.9 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 2.46 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 June 30, 2018 , and changes during the six months then ended (in thousands, except per share data): Number of Shares Weighted- Average Grant-Date Fair Value Nonvested at January 1, 2018 1,754 $48.45 Granted 982 72.56 Vested (554 ) 46.99 Forfeited (191 ) 50.03 Nonvested at June 30, 2018 1,991 $60.60 The total fair value of RSAs and RSUs vested during the three months ended June 30, 2018 and 2017 was $ 5.7 million and $4.7 million , respectively. The total fair value of RSAs and RSUs vested during the six months ended June 30, 2018 and 2017 was $37.3 million and $31.0 million , respectively. As of June 30, 2018 , there was $107.0 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 2.65 years . Performance-Based Restricted Stock Units During the three months ended June 30, 2018 , the Company granted (1) 6 thousand PBRSUs ("2018 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, 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) 5 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 PBRSUs with performance conditions based on achievement of certain individual and team objectives. No PBRSUs were granted during the three months ended June 30, 2017 . During the six months ended June 30, 2018 , the Company granted: (1) 122 thousand 2018 TSR PBRSUs; (2) 122 thousand 2018 Net Income PBRSUs. The Company also granted an immaterial number of other PBRSUs with performance conditions based on achievement of certain individual and team objectives. During the six months ended June 30, 2017 , the Company granted: (1) 132 thousand PBRSUs ("2017 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, 2019, 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) 132 thousand PBRSUs ("2017 Net Income PBRSUs") with performance conditions based on the compound annual growth rate of net income over the three-year period ending December 31, 2019, 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 fair value of PBRSUs with market conditions granted during the three and six months ended June 30, 2018 and 2017 was estimated as of the date of grant using a Monte Carlo valuation model with the following weighted average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility - Medidata 36 % 42 % 37 % 42 % Expected volatility - comparison index 43 % 43 % 42 % 43 % Expected life 2.69 years 2.85 years 2.85 years 2.85 years Risk-free interest rate 2.58 % 1.40 % 2.37 % 1.40 % Dividend yield — — — — The following table summarizes the status of the Company’s PBRSUs based upon expected performance as of June 30, 2018 , and changes during the six months then ended (in thousands, except per share data): Net Income TSR Other Total Number of Shares Weighted-Average Grant Date Fair Value Nonvested at January 1, 2018 110 613 13 736 $ 62.96 Granted (based on performance at 100% of targeted levels) 122 122 2 246 85.92 Adjustment related to expected performance — 171 10 181 78.54 Vested — (120 ) — (120 ) 69.92 Forfeited — — (1 ) (1 ) 77.64 Nonvested at June 30, 2018 232 786 24 1,042 $ 70.27 No PBRSUs vested during the three months ended June 30, 2018 and 2017 . The total fair value of PBRSUs vested during the six months ended June 30, 2018 and 2017 was $8.1 million and $5.1 million , respectively. As of June 30, 2018 , there was $30.3 million in unrecognized compensation cost related to all nonvested PBRSUs. This cost is expected to be recognized over a weighted-average remaining period of 1.72 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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility 37 % 39 % 37 % 39 % Expected life 1.70 years 1.49 years 1.70 years 1.49 years Risk-free interest rate 1.09 % 0.62 % 1.09 % 0.62 % Dividend yield — — — — During the three and six months ended June 30, 2018 , 150 thousand shares were purchased under the ESPP at a weighted-average price of $43.04 . During the three and six months ended June 30, 2017 , 103 thousand shares were purchased under the ESPP at a weighted-average price of $40.50 . As of June 30, 2018 , there was $2.2 million in unrecognized compensation cost related to ESPP shares. This cost is expected to be recognized over a weighted-average remaining period of 1.23 years. Modifications Aggregate incremental expense associated with modifications to stock options, RSAs and PBRSUs in connection with separation agreements during the three months ended June 30, 2018 and 2017 was $0.2 million and none , respectively. Incremental expense during the six months ended June 30, 2018 and 2017 was $0.4 million and $0.1 million , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
ACCUMULATED OTHER COMPREHENSIVE INCOME	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The changes in the balances of each component of accumulated other comprehensive loss during the six months ended June 30, 2018 are as follows (in thousands): Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Total Balance as of January 1, 2018 $ (2,459 ) $ (918 ) $ (3,377 ) Other comprehensive income (684 ) (429 ) (1,113 ) Balance as of June 30, 2018 $ (3,143 ) $ (1,347 ) $ (4,490 ) For the six months ended June 30, 2018 and 2017 , reclassifications of items from accumulated other comprehensive loss to net income were insignificant.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2018
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. Given the Company's election to settle the principal amount of the Notes (see Note 8 , "Debt") in cash upon conversion, their dilutive effect is reflected in diluted earnings per share using the treasury stock method, which considers the number of shares that would be required to settle any 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 and six months ended June 30, 2018 and 2017 is shown in the following table (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Numerator Net income $ 16,589 $ 7,541 (1) $ 26,914 $ 17,521 (1) Denominator Denominator for basic earnings per share: Weighted average common shares outstanding 57,448 56,433 57,252 56,254 Denominator for diluted earnings per share: Dilutive potential common shares: Stock options 866 1,001 897 976 Restricted stock awards and units 612 798 752 835 Performance-based restricted stock units 610 625 586 560 Employee stock purchase plan 220 149 181 114 Convertible senior notes 1,118 829 896 312 Weighted average common shares outstanding with assumed conversion 60,874 59,835 60,564 59,051 Basic earnings per share $ 0.29 $ 0.13 (1) $ 0.47 $ 0.31 (1) Diluted earnings per share $ 0.27 $ 0.13 (1) $ 0.44 $ 0.30 (1) (1) Figures for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. Anti-dilutive common stock equivalents excluded from the calculation of diluted earnings per share for the three and six months ended June 30, 2018 and 2017 are shown in the following table (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Stock options 79 94 78 202 Restricted stock awards and units 34 1 30 10 Performance-based restricted stock units — — — — Employee stock purchase plan 84 275 84 275 Total 197 370 192 487

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Unrecognized Tax Benefits The Company's unrecognized tax benefits were approximately $4.1 million as of June 30, 2018 , and were unchanged from December 31, 2017 . U.S. Tax Reform The U.S. Tax Cuts and Jobs Act (the "Tax Act") was enacted on December 22, 2017, is effective January 1, 2018, and introduces significant changes to U.S. income tax law. Due to the timing of the enactment and the complexity involved in applying the provisions of the Tax Act, the Company made a reasonable estimate of the effects and recorded provisional amounts in its financial statements in the fourth quarter of 2017. The Company made immaterial revisions to the provisional amounts during the first quarter of 2018. No further revisions were made during the three months ended June 30, 2018 . The Company will continue to interpret the Tax Act and any additional guidance issued by the U.S. Treasury Department, the Internal Revenue Service, and other standard-setting bodies, and may make further adjustments to these provisional amounts in future periods, but no later than twelve months from the date of enactment.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
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. Wire Transaction Claim — In September 2014, the Company was the victim of a crime involving the transfer of $4.8 million to an overseas account. As a result, the Company recorded charges of $4.9 million and $0.9 million to its operating costs and expenses in the third and fourth quarters of 2014, respectively, for the loss and related investigation costs incurred. The Company filed an insurance claim for its loss, and its insurer, Federal Insurance Co. ("Federal"), denied coverage. The Company commenced legal action, alleging that Federal had wrongly denied coverage. On July 21, 2017, the United States District Court for the Southern District of New York granted the Company's motion for summary judgment, and denied Federal's motion. In light of this ruling, the Company recognized the probable recovery of the originally recorded $4.8 million loss as a credit to its operating costs and expenses in the third quarter of 2017. Federal filed a Notice of Appeal with the United States Court of Appeals for the Second Circuit ("the Court") on August 11, 2017. On July 6, 2018, the Court affirmed the Company's judgment against Federal, awarding the Company a total of $5.8 million, which includes interest. On July 20, 2018, Federal filed a Petition for Panel Rehearing and Rehearing En Banc, which is currently pending with the Court.

Subsequent Event

Subsequent Event	6 Months Ended
	Jun. 30, 2018
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT The Notes matured on August 1, 2018, and the Company received notices of conversion for substantially all of the outstanding Notes prior to the maturity date. Pursuant to its election, the Company settled the $287.5 million principal amount of the Notes in cash and the conversion premium in shares of its common stock. The Company issued 1,439,704 shares of common stock in settlement of the premium, determined by a calculation based on the volume-weighted average price of the Company's common stock over the 40 trading-day observation period beginning on and including June 1, 2018, as specified in the indenture governing the Notes.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Basis of presentation	Basis of Presentation — The accompanying interim condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017 , the condensed consolidated statements of operations for the three and six months ended June 30, 2018 and 2017 , the condensed consolidated statements of comprehensive income for the three and six months ended June 30, 2018 and 2017 , and the condensed consolidated statements of cash flows for the six months ended June 30, 2018 and 2017 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, 2017 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2018 . 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 June 30, 2018 , results of its operations for the three and six months ended June 30, 2018 and 2017 , comprehensive income for the three and six months ended June 30, 2018 and 2017 , and cash flows for the six months ended June 30, 2018 and 2017 . The results of operations for the three and six months ended June 30, 2018 are not necessarily indicative of the results that may be expected for the year ending December 31, 2018 .
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 June 30, 2018 and December 31, 2017 , unbilled accounts receivable of $11.8 million and $12.5 million , respectively, were included in accounts receivable on the Company's condensed consolidated balance sheets. In general, there is a direct relationship between the Company's accounts receivable balance and its transaction volume.
Revenue recognition	Revenue Recognition — Revenues are recognized when control of the promised goods or services are transferred to a customer, in an amount that reflects the consideration that the Company expects to receive in exchange for those goods or services. The Company derives its revenues from two sources: (1) subscription revenues, which are comprised of subscription fees from customers utilizing the Company's cloud-based solutions; and (2) professional services, such as training, implementation, consulting, interface creation, trial configuration, data testing, reporting, procedure documentation, and other customer-specific services. The Company applies the following five steps in order to determine the appropriate amount of revenue to be recognized as it fulfills its obligations under each of its agreements: • identify the contract with a customer; • identify the performance obligations in the contract; • determine the transaction price; • allocate the transaction price to performance obligations in the contract; and • recognize revenue as the performance obligation is satisfied. For further information, see Note 2 , “Revenues,” to the condensed consolidated financial statements included in this Quarterly Report on Form 10-Q. Subscription The Company derives its subscription revenues from multi-study and single-study arrangements that grant the customer the right to utilize its cloud-based solutions for a specified term. Multi-study arrangements grant the customer the right to manage a predetermined number of clinical trials simultaneously for a term typically ranging from one to five years. Single-study arrangements allow customers to use the Company’s solutions on a per-trial basis. Subscription services are transferred to customers over time. The Company uses the passage of time as its measurement method, as control of the services is simultaneously transferred to and used by the customer throughout the contractual term. As a result, revenue for subscription services is recognized ratably over the term of the agreement, which is generally aligned with the dates during which the customer has access to the Company’s cloud-based applications. Fees for subscription services are generally invoiced in advance installments and typically have payment terms of net 30 or net 45 days. Professional Services The Company also makes available a range of professional services, including implementation, enablement, training, and strategic consulting. Professional services do not result in significant alterations to the underlying solutions. Professional services engagements involving implementation and training tend to be shorter term in nature (expected durations of less than one year), while enablement and consulting type engagements are longer in term (expected durations of one to five years). Professional services are transferred to customers over time. For fixed price arrangements, the Company measures its progress in transferring services to a customer using a proportional performance method. The proportional performance method is reflective of the variable rates at which services are transferred to the customer, and results in recognition of revenue that is consistent with the services provided to date. For time and materials contracts, the Company recognizes revenue as services are rendered. Fees for professional services are generally invoiced either in milestone installments based on work performed or, for time and materials based arrangements, as services are rendered, and typically have payment terms of net 30 or net 45 days. Performance Obligations The Company enters into contracts that contain multiple distinct performance obligations, combining a cloud-based technology subscription with various professional services. The Company has determined that its subscriptions and professional services are distinct performance obligations because both can be and are sold by the Company on a standalone basis, and because other vendors sell similar technologies and services on a standalone basis. For each performance obligation identified, the Company estimates the standalone selling price, which represents the price at which the Company would sell the good or service separately. If the standalone selling price is not observable through past transactions, the Company estimates the standalone selling price, taking into account available information such as market conditions, review of historical pricing data, and internal pricing guidelines related to the performance obligations. The Company then allocates the transaction price among those obligations based on the estimation of standalone selling price. Transaction prices for the Company's contracts may include both fixed and variable consideration, but do not contain significant financing components or noncash consideration. Cost to Obtain and Fulfill a Contract The Company capitalizes commission expenses paid to internal sales personnel that are incremental to obtaining customer contracts. Costs related to nonrenewable contracts are deferred and amortized on a straight-line basis over the duration of the contractual term. Costs related to renewable contracts are deferred and amortized on a straight-line basis over a period equal to twice the contractual term, which the Company deems to be the expected period of benefit for these costs. In developing this estimate, the Company considered its historical renewal rates and customer retention rates, as well as technology development life cycles and other industry factors. The Company defers these costs in prepaid commission expense and other current assets, net of any long term portion included in other noncurrent assets in the Company's condensed consolidated balance sheets. These costs are periodically reviewed for impairment.
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 May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers , which supersedes the existing accounting standards for revenue recognition in Accounting Standards Codification ("ASC") 605, and provides principles for recognizing revenue for the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. ASU No. 2014-09 also creates a new subtopic under ASC 340, Other Assets and Deferred Costs , which discusses the deferral of incremental costs of obtaining a contract with a customer, including the period of amortization of such costs. The Company adopted ASU No. 2014-09 on January 1, 2018, using the full retrospective method. Refer to Note 2 , "Revenues," for related disclosures. The following tables summarize the impact of adoption of ASC 606 on the Company’s condensed consolidated statements of operations for the three and six months ended June 30, 2017 (in thousands, except per share data): Three Months Ended June 30, 2017 Six Months Ended June 30, 2017 As Reported Under ASC 605 Impact of ASC 606 Adoption As Adjusted As Reported Under ASC 605 Impact of ASC 606 Adoption As Adjusted Revenues Subscription $ 114,291 $ (1,387 ) $ 112,904 $ 221,361 $ (564 ) $ 220,797 Professional services 23,123 — 23,123 42,874 — 42,874 Total revenues 137,414 (1,387 ) 136,027 264,235 (564 ) 263,671 Operating costs and expenses Sales and marketing 32,784 (305 ) 32,479 62,893 (188 ) 62,705 Operating income 13,743 (1,082 ) 12,661 25,916 (376 ) 25,540 Provision for income taxes 2,438 (373 ) 2,065 1,937 (129 ) 1,808 Net income $ 8,250 $ (709 ) $ 7,541 $ 17,768 $ (247 ) $ 17,521 Earnings per share Basic $ 0.15 $ (0.02 ) $ 0.13 $ 0.32 $ (0.01 ) $ 0.31 Diluted $ 0.14 $ (0.01 ) $ 0.13 $ 0.30 $ — $ 0.30 The adoption has no cash flow impact. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities , which amends certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. ASU No. 2016-01 is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual periods. The Company adopted ASU No. 2016-01 on January 1, 2018, and the adoption did not have a material impact on its condensed consolidated financial statements. In August 2016, the FASB issued ASU No. 2016-15, Cash Flows - Classification of Certain Cash Receipts and Cash Payments , which addresses the diversity in practice around presentation of certain cash receipts and payments in the statement of cash flows. ASU No. 2016-15 is effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. The Company adopted ASU No. 2016-15 on January 1, 2018, and the adoption did not have a material impact on its condensed consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-01, Clarifying the Definition of a Business , which provides a more specific definition of a business than was afforded under previous guidance. The definition of a business affects many areas of accounting, including acquisitions, disposals, goodwill, and consolidation. ASU No. 2017-01 is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. The Company adopted ASU No. 2017-01 on January 1, 2018, and the adoption had no impact on its condensed consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, Scope of Modification Accounting , which clarifies when a change in the terms or conditions of a share-based payment award should be accounted for as a modification. ASU No. 2017-09 is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. The Company adopted ASU No. 2017-09 on January 1, 2018, and the adoption did not have a material impact on its condensed consolidated financial statements. In June 2018. the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which simplifies several aspects of the accounting for nonemployee share-based payment transactions by expanding the scope of the stock-based compensation guidance in ASC 718 to include share-based payment transactions for acquiring goods and services from non-employees. ASU No. 2018-07 is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods. Early adoption is permitted, but entities may not adopt prior to adopting the new revenue recognition guidance in ASC 606. The Company early adopted ASU No. 2018-07 in the second quarter of 2018, and the adoption did not have a material impact on its 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, except as described below. In February 2016, the FASB issued 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 new guidance also adds quantitative and qualitative disclosure requirements around leasing activities. ASU No. 2016-02 is effective for annual periods beginning after December 15, 2018, including interim periods within those annual periods. The Company will adopt ASU No. 2016-02 on January 1, 2019. The Company expects that this standard will have a material effect on its financial condition, with the most significant change relating to the recognition of new right-of-use assets and lease liabilities on its consolidated balance sheets for its facility operating leases. The Company estimates that the hypothetical balance sheet impact of recognizing these assets and liabilities would be approximately 5% of total assets and 10% of total liabilities as of June 30, 2018 , based on the present value of the remaining minimum rental payments under current leasing standards for existing operating leases. The final quantitative impact of the adoption of the new lease guidance is subject to change from these estimates, pending the completion of the Company's implementation in the first quarter of 2019. 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 will adopt ASU No. 2018-02 on January 1, 2019, and does not expect the adoption to have a material impact on its condensed consolidated financial statements.
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. Given the Company's election to settle the principal amount of the Notes (see Note 8 , "Debt") in cash upon conversion, their dilutive effect is reflected in diluted earnings per share using the treasury stock method, which considers the number of shares that would be required to settle any premium above principal at the average stock price for the period.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Impact of ASC 606 adoption on prior periods	The following tables summarize the impact of adoption of ASC 606 on the Company’s condensed consolidated statements of operations for the three and six months ended June 30, 2017 (in thousands, except per share data): Three Months Ended June 30, 2017 Six Months Ended June 30, 2017 As Reported Under ASC 605 Impact of ASC 606 Adoption As Adjusted As Reported Under ASC 605 Impact of ASC 606 Adoption As Adjusted Revenues Subscription $ 114,291 $ (1,387 ) $ 112,904 $ 221,361 $ (564 ) $ 220,797 Professional services 23,123 — 23,123 42,874 — 42,874 Total revenues 137,414 (1,387 ) 136,027 264,235 (564 ) 263,671 Operating costs and expenses Sales and marketing 32,784 (305 ) 32,479 62,893 (188 ) 62,705 Operating income 13,743 (1,082 ) 12,661 25,916 (376 ) 25,540 Provision for income taxes 2,438 (373 ) 2,065 1,937 (129 ) 1,808 Net income $ 8,250 $ (709 ) $ 7,541 $ 17,768 $ (247 ) $ 17,521 Earnings per share Basic $ 0.15 $ (0.02 ) $ 0.13 $ 0.32 $ (0.01 ) $ 0.31 Diluted $ 0.14 $ (0.01 ) $ 0.13 $ 0.30 $ — $ 0.30

Revenues (Tables)

Revenues (Tables)	6 Months Ended
	Jun. 30, 2018
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 and six months ended June 30, 2018 and 2017 (in thousands): Three Months Ended June 30, 2018 2017 Subscription Professional Services Total Subscription Professional Services Total Revenues: United States $ 99,646 $ 18,526 $ 118,172 $ 85,425 $ 16,708 $ 102,133 Rest of Americas 1,689 277 1,966 57 196 253 Total Americas 101,335 18,803 120,138 85,482 16,904 102,386 Japan 7,665 1,261 8,926 7,627 1,222 8,849 Rest of Asia Pacific 3,875 1,243 5,118 2,603 1,351 3,954 Total Asia Pacific 11,540 2,504 14,044 10,230 2,573 12,803 Europe, Middle East and Africa 17,611 4,112 21,723 17,192 3,646 20,838 Total $ 130,486 $ 25,419 $ 155,905 $ 112,904 $ 23,123 $ 136,027 Six Months Ended June 30, 2018 2017 Subscription Professional Services Total Subscription Professional Services Total Revenues: United States $ 195,811 $ 34,510 $ 230,321 $ 169,764 $ 30,616 $ 200,380 Rest of Americas 1,998 481 2,479 87 221 308 Total Americas 197,809 34,991 232,800 169,851 30,837 200,688 Japan 15,777 3,055 18,832 14,276 3,029 17,305 Rest of Asia Pacific 7,576 2,381 9,957 4,952 2,297 7,249 Total Asia Pacific 23,353 5,436 28,789 19,228 5,326 24,554 Europe, Middle East and Africa 36,143 7,371 43,514 31,718 6,711 38,429 Total $ 257,305 $ 47,798 $ 305,103 $ 220,797 $ 42,874 $ 263,671
Contract balances	The following table provides information about changes in the Company's deferred revenue balances during the six months ended June 30, 2018 and 2017 (in thousands): Deferred Revenue 2018 2017 Balance as of January 1 $ 82,631 $ 75,850 Revenue recognized that was included in deferred revenue at the beginning of the period (71,137 ) (64,581 ) Revenue recognized that was not included in deferred revenue at the beginning of the period (233,400 ) (198,379 ) Increases due to invoicing 297,161 277,087 Other 813 (2,705 ) Balance as of June 30 $ 76,068 $ 87,272

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
Marketable securities by security type	The following tables provide the Company’s marketable securities by security type as of June 30, 2018 and December 31, 2017 (in thousands): As of June 30, 2018 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 333,185 $ — $ (1,650 ) $ 331,535 U.S. government agency debt securities 25,690 — (146 ) 25,544 Total $ 358,875 $ — $ (1,796 ) $ 357,079 As of December 31, 2017 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 392,481 $ — $ (1,334 ) $ 391,147 U.S. government agency debt securities 35,016 — (155 ) 34,861 Total $ 427,497 $ — $ (1,489 ) $ 426,008
Contractual maturities of marketable securities	Contractual maturities of the Company’s marketable securities as of June 30, 2018 and December 31, 2017 are summarized as follows (in thousands): As of June 30, 2018 As of December 31, 2017 Cost Estimated Fair Value Cost Estimated Fair Value Due in one year or less $ 288,628 $ 287,603 $ 247,495 $ 246,967 Due in one to five years 70,247 69,476 180,002 179,041 Total $ 358,875 $ 357,079 $ 427,497 $ 426,008
Fair market value and gross unrealized losses of marketable securities	The following tables provide the fair market value and gross unrealized losses of the Company's marketable securities with unrealized losses, aggregated by security type, as of June 30, 2018 and December 31, 2017 (in thousands): In Loss Position for Less than 12 Months As of June 30, 2018 As of December 31, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 254,385 $ (1,353 ) $ 295,224 $ (1,137 ) U.S. government agency debt securities 10,575 (116 ) 18,431 (86 ) Total $ 264,960 $ (1,469 ) $ 313,655 $ (1,223 ) In Loss Position for More than 12 Months As of June 30, 2018 As of December 31, 2017 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 77,151 $ (297 ) $ 95,923 $ (197 ) U.S. government agency debt securities 14,970 (30 ) 16,430 (69 ) Total $ 92,121 $ (327 ) $ 112,353 $ (266 )

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Financial assets and liabilities measured at fair value on a recurring basis	The following table summarizes, as of June 30, 2018 and December 31, 2017 , 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, 2017 (in thousands): As of June 30, 2018 As of December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 118,584 $ — $ — $ 118,584 $ 237,149 $ — $ — $ 237,149 Money market funds 1,714 — — 1,714 176 — — 176 Total cash and cash equivalents 120,298 — — 120,298 237,325 — — 237,325 Commercial paper and corporate bonds — 331,534 — 331,534 — 391,147 — 391,147 U.S. government agency debt securities — 25,545 — 25,545 — 34,861 — 34,861 Total marketable securities — 357,079 — 357,079 — 426,008 — 426,008 Total financial assets measured at fair value on a recurring basis $ 120,298 $ 357,079 $ — $ 477,377 $ 237,325 $ 426,008 $ — $ 663,333 Contingent consideration – short-term $ — $ — $ 1,351 $ 1,351 $ — $ — $ 3,993 $ 3,993 Contingent consideration – long-term — — 581 581 — — 2,012 2,012 Total financial liabilities measured at fair value on a recurring basis $ — $ — $ 1,932 $ 1,932 $ — $ — $ 6,005 $ 6,005
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 financial liabilities during the six months ended June 30, 2018 (in thousands): Balance as of January 1, 2018 $ 6,005 Amounts earned by sellers (4,080 ) Fair value adjustment (included in general and administrative expenses) 7 Balance as of June 30, 2018 $ 1,932

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of goodwill	The change in the carrying amount of goodwill during the six months ended June 30, 2018 was as follows (in thousands): Balance as of January 1, 2018 $ 47,435 Additions related to current period acquisition - SHYFT 151,857 Final purchase price adjustment - Mytrus (422 ) Foreign currency translation adjustments (90 ) Balance as of June 30, 2018 $ 198,780
Intangible assets	Total intangible assets are summarized as follows (in thousands): As of June 30, 2018 As of December 31, 2017 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 44,407 $ (11,152 ) $ 33,255 $ 24,436 $ (8,883 ) $ 15,553 Customer relationships 24,481 (2,907 ) 21,574 4,489 (2,595 ) 1,894 Non-competition agreements 260 (151 ) 109 260 (120 ) 140 Total $ 69,148 $ (14,210 ) $ 54,938 $ 29,185 $ (11,598 ) $ 17,587
Annual amortization for the next five years	Future amortization of intangible assets is expected to be as follows (in thousands): Remainder of 2018 $ 6,339 2019 12,486 2020 11,742 2021 11,472 2022 8,877 2023 4,022 Thereafter — Total $ 54,938

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2018
1.00% convertible senior notes [Member]
Debt Instrument [Line Items]
Schedule of debt	The Company's 1.00% convertible senior notes (the "Notes"), issued in August 2013, consisted of the following components as of June 30, 2018 and December 31, 2017 (in thousands): June 30, December 31, Equity component, net of equity issue costs $ 60,222 $ 60,222 Liability component: Principal 287,500 287,500 Less: unamortized debt discount (1,646 ) (8,661 ) Less: unamortized debt issuance costs (106 ) (745 ) Net carrying amount $ 285,748 $ 278,094
Interest expense	The following table sets forth total interest expense recognized related to the Notes for the three and six months ended June 30, 2018 and 2017 (in thousands except percentages): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Contractual interest expense $ 719 $ 719 $ 1,438 $ 1,438 Amortization of debt issuance costs 320 320 639 639 Amortization of debt discount 3,534 3,328 7,015 6,607 Total $ 4,573 $ 4,367 $ 9,092 $ 8,684 Effective interest rate 6.5 % 6.5 % 6.5 % 6.5 %
Credit facility [Member]
Debt Instrument [Line Items]
Schedule of debt	The Credit Facility consisted of the following components as of June 30, 2018 and December 31, 2017 (in thousands): June 30, 2018 December 31, 2017 Term Loans $ 98,750 $ 100,000 Less: unamortized debt issuance costs (1,942 ) (2,159 ) Net carrying amount (1) $ 96,808 $ 97,841 (1) Of the total carrying amount of the Term Loans, short-term maturities of $4.9 million and $5.0 million were included in accrued expenses and other on the Company's condensed consolidated balance sheets as of June 30, 2018 and December 31, 2017, respectively.
Interest expense	The following table sets forth total interest expense recognized related to the Credit Facility for the three and six months ended June 30, 2018 (in thousands): Three Months Ended Six Months Ended June 30, 2018 Contractual interest expense on Term Loans $ 811 $ 1,559 Amortization of debt issuance costs 109 217 Unused commitment fee on Revolver 209 409 Total $ 1,129 $ 2,185

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Components of stock-based compensation expense	For the three and six months ended June 30, 2018 and 2017 , the components of stock-based compensation expense were as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Stock options $ 522 $ 938 $ 1,094 $ 1,855 Restricted stock awards and units 9,024 7,769 16,891 14,688 Performance-based restricted stock units 3,932 3,074 7,159 4,702 Employee stock purchase plan 1,712 969 3,260 1,897 Total stock-based compensation (1) $ 15,190 $ 12,750 $ 28,404 $ 23,142 (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	The fair value of each stock option granted during the three and six months ended June 30, 2018 and 2017 was estimated on the date of grant using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility 42 % 43 % 42 % 44 % Expected life 4.78 years 6.00 years 4.78 years 6.00 years Risk-free interest rate 2.82 % 2.02 % 2.82 % 2.07 % Dividend yield — — — —
Summary of activities and changes in stock option plans	The following table summarizes the status of the Company's stock options as of June 30, 2018 , and changes during the six 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, 2018 1,511 $22.72 Granted 35 72.27 Exercised (248 ) 25.62 Forfeited (34 ) 45.55 Expired — — Outstanding at June 30, 2018 1,264 $22.91 3.88 $72,894 Exercisable at June 30, 2018 1,092 $17.45 3.16 $68,942 Vested and expected to vest at June 30, 2018 1,252 $22.52 3.83 $72,657
Summary of nonvested restricted stock awards	The following table summarizes the status of the Company’s nonvested time-based RSAs and RSUs as of June 30, 2018 , and changes during the six months then ended (in thousands, except per share data): Number of Shares Weighted- Average Grant-Date Fair Value Nonvested at January 1, 2018 1,754 $48.45 Granted 982 72.56 Vested (554 ) 46.99 Forfeited (191 ) 50.03 Nonvested at June 30, 2018 1,991 $60.60
Fair value of TSR PBRSUs	The fair value of PBRSUs with market conditions granted during the three and six months ended June 30, 2018 and 2017 was estimated as of the date of grant using a Monte Carlo valuation model with the following weighted average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility - Medidata 36 % 42 % 37 % 42 % Expected volatility - comparison index 43 % 43 % 42 % 43 % Expected life 2.69 years 2.85 years 2.85 years 2.85 years Risk-free interest rate 2.58 % 1.40 % 2.37 % 1.40 % 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 June 30, 2018 , and changes during the six months then ended (in thousands, except per share data): Net Income TSR Other Total Number of Shares Weighted-Average Grant Date Fair Value Nonvested at January 1, 2018 110 613 13 736 $ 62.96 Granted (based on performance at 100% of targeted levels) 122 122 2 246 85.92 Adjustment related to expected performance — 171 10 181 78.54 Vested — (120 ) — (120 ) 69.92 Forfeited — — (1 ) (1 ) 77.64 Nonvested at June 30, 2018 232 786 24 1,042 $ 70.27
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 June 30, Six Months Ended June 30, 2018 2017 2018 2017 Expected volatility 37 % 39 % 37 % 39 % Expected life 1.70 years 1.49 years 1.70 years 1.49 years Risk-free interest rate 1.09 % 0.62 % 1.09 % 0.62 % Dividend yield — — — —

Accumulated Other Comprehensi29

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of accumulated other comprehensive loss	The changes in the balances of each component of accumulated other comprehensive loss during the six months ended June 30, 2018 are as follows (in thousands): Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Total Balance as of January 1, 2018 $ (2,459 ) $ (918 ) $ (3,377 ) Other comprehensive income (684 ) (429 ) (1,113 ) Balance as of June 30, 2018 $ (3,143 ) $ (1,347 ) $ (4,490 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
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 and six months ended June 30, 2018 and 2017 is shown in the following table (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Numerator Net income $ 16,589 $ 7,541 (1) $ 26,914 $ 17,521 (1) Denominator Denominator for basic earnings per share: Weighted average common shares outstanding 57,448 56,433 57,252 56,254 Denominator for diluted earnings per share: Dilutive potential common shares: Stock options 866 1,001 897 976 Restricted stock awards and units 612 798 752 835 Performance-based restricted stock units 610 625 586 560 Employee stock purchase plan 220 149 181 114 Convertible senior notes 1,118 829 896 312 Weighted average common shares outstanding with assumed conversion 60,874 59,835 60,564 59,051 Basic earnings per share $ 0.29 $ 0.13 (1) $ 0.47 $ 0.31 (1) Diluted earnings per share $ 0.27 $ 0.13 (1) $ 0.44 $ 0.30 (1) (1) Figures for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606.
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 and six months ended June 30, 2018 and 2017 are shown in the following table (in thousands, except per share data): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Stock options 79 94 78 202 Restricted stock awards and units 34 1 30 10 Performance-based restricted stock units — — — — Employee stock purchase plan 84 275 84 275 Total 197 370 192 487

Summary of Significant Accoun31

Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Revenues
Subscription		$ 130,486	$ 112,904	[1]	$ 257,305	$ 220,797	[1]
Professional services		25,419	23,123		47,798	42,874
Total revenues		155,905	136,027		305,103	263,671
Operating costs and expenses:
Sales and marketing	[2],[3]	37,106	32,479	[1]	73,967	62,705	[1]
Operating income		12,837	12,661		26,163	25,540
Provision for income taxes		605	2,065	[1]	23	1,808	[1]
Net income		$ 16,589	$ 7,541	[1],[4]	$ 26,914	$ 17,521	[1],[4]
Earnings per share
Basic		$ 0.29	$ 0.13	[1]	$ 0.47	$ 0.31	[1]
Diluted		$ 0.27	$ 0.13	[1]	$ 0.44	$ 0.30	[1]
Previously reported under ASC 605
Revenues
Subscription			$ 114,291			$ 221,361
Professional services			23,123			42,874
Total revenues			137,414			264,235
Operating costs and expenses:
Sales and marketing			32,784			62,893
Operating income			13,743			25,916
Provision for income taxes			2,438			1,937
Net income			$ 8,250			$ 17,768
Earnings per share
Basic			$ 0.15			$ 0.32
Diluted			$ 0.14			$ 0.30
Impact of adoption of ASC 606
Revenues
Subscription			$ (1,387)			$ (564)
Professional services			0			0
Total revenues			(1,387)			(564)
Operating costs and expenses:
Sales and marketing			(305)			(188)
Operating income			(1,082)			(376)
Provision for income taxes			(373)			(129)
Net income			$ (709)			$ (247)
Earnings per share
Basic			$ (0.02)			$ (0.01)
Diluted			$ (0.01)			$ 0
[1]	The condensed consolidated statements of operations for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."
[2]	Amortization of intangible assets included in cost of revenues and operating costs and expenses
[3]	Stock-based compensation expense included in cost of revenues and operating costs and expenses
[4]	The condensed consolidated statements of comprehensive income for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Unbilled receivables	$ 11.8	$ 12.5

Revenues (Details)

Revenues (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Subscription	$ 130,486	$ 112,904	[1]	$ 257,305	$ 220,797	[1]
Professional services	25,419	23,123		47,798	42,874
Total revenues	155,905	136,027		305,103	263,671
United States
Disaggregation of Revenue [Line Items]
Subscription	99,646	85,425		195,811	169,764
Professional services	18,526	16,708		34,510	30,616
Total revenues	118,172	102,133		230,321	200,380
Rest of Americas [Member]
Disaggregation of Revenue [Line Items]
Subscription	1,689	57		1,998	87
Professional services	277	196		481	221
Total revenues	1,966	253		2,479	308
Total Americas [Member]
Disaggregation of Revenue [Line Items]
Subscription	101,335	85,482		197,809	169,851
Professional services	18,803	16,904		34,991	30,837
Total revenues	120,138	102,386		232,800	200,688
Japan
Disaggregation of Revenue [Line Items]
Subscription	7,665	7,627		15,777	14,276
Professional services	1,261	1,222		3,055	3,029
Total revenues	8,926	8,849		18,832	17,305
Rest of Asia Pacific
Disaggregation of Revenue [Line Items]
Subscription	3,875	2,603		7,576	4,952
Professional services	1,243	1,351		2,381	2,297
Total revenues	5,118	3,954		9,957	7,249
Total Asia Pacific
Disaggregation of Revenue [Line Items]
Subscription	11,540	10,230		23,353	19,228
Professional services	2,504	2,573		5,436	5,326
Total revenues	14,044	12,803		28,789	24,554
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Subscription	17,611	17,192		36,143	31,718
Professional services	4,112	3,646		7,371	6,711
Total revenues	$ 21,723	$ 20,838		$ 43,514	$ 38,429
[1]	The condensed consolidated statements of operations for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."

Revenues (Details 1)

Revenues (Details 1) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Change in contract liabilities
Contract liabilities, balance at beginning of period	$ 82,631	$ 75,850
Revenue recognized that was included in deferred revenue at the beginning of the period	(71,137)	(64,581)
Revenue recognized that was not included in deferred revenue at the beginning of the period	(233,400)	(198,379)
Increase due to invoicing	297,161	277,087
Other	813	(2,705)
Contract liabilities, balance at end of period	$ 76,068	$ 87,272

Revenues (Details Textual)

Revenues (Details Textual) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
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.
Contract assets	$ 0		$ 0		$ 0
Year through which remaining performance obligations extend			2,030
Unsatisfied subscription performance obligations	1,000		$ 1,000
Unsatisfied subscription performance obligations, portion expected to be satisfied in current fiscal year	257		257
Unsatisfied subscription performance obligations, portion expected to be satisfied in following fiscal year	371		371
Unsatisfied subscription performance obligations, portion expected to be satisfied thereafter	389		$ 389
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	44.4		$ 44.4		$ 36.9
Capitalized contract costs, amortization	4.6	$ 5.7	9.5	$ 12.1
Capitalized contract costs, accumulated impairment	$ 0		$ 0

Stockholders' Equity (Details)

Stockholders' Equity (Details) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Shares paid for tax withholding for share based compensation	271,585	260,737
Shares paid for tax withholding for share based compensation, average price	$ 67.23	$ 56.71
Forfeited restricted stock awards transferred to treasury stock	189,668	154,106

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Marketable securities by security type
Cost	$ 358,875	$ 427,497
Gross unrealized gains	0	0
Gross unrealized losses	(1,796)	(1,489)
Estimated fair value	357,079	426,008
Commercial paper and corporate bonds [Member]
Marketable securities by security type
Cost	333,185	392,481
Gross unrealized gains	0	0
Gross unrealized losses	(1,650)	(1,334)
Estimated fair value	331,535	391,147
U.S. government agency debt securities [Member]
Marketable securities by security type
Cost	25,690	35,016
Gross unrealized gains	0	0
Gross unrealized losses	(146)	(155)
Estimated fair value	$ 25,544	$ 34,861

Investments (Details 1)

Investments (Details 1) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Marketable securities by contractual maturity
Cost	$ 358,875	$ 427,497
Estimated fair value	357,079	426,008
One year or less [Member]
Marketable securities by contractual maturity
Cost	288,628	247,495
Estimated fair value	287,603	246,967
One to five years [Member]
Marketable securities by contractual maturity
Cost	70,247	180,002
Estimated fair value	$ 69,476	$ 179,041

Investments (Details 2)

Investments (Details 2) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Fair market value and gross unrealized losses of marketable securities
Less than 12 months in unrealized loss position - fair value	$ 264,960	$ 313,655
Less than 12 months in unrealized loss position - gross unrealized losses	(1,469)	(1,223)
12 months or more in unrealized loss position - fair value	92,121	112,353
12 months or more in unrealized loss position - gross unrealized losses	(327)	(266)
Commercial paper and corporate bonds [Member]
Fair market value and gross unrealized losses of marketable securities
Less than 12 months in unrealized loss position - fair value	254,385	295,224
Less than 12 months in unrealized loss position - gross unrealized losses	(1,353)	(1,137)
12 months or more in unrealized loss position - fair value	77,151	95,923
12 months or more in unrealized loss position - gross unrealized losses	(297)	(197)
U.S. government agency debt securities [Member]
Fair market value and gross unrealized losses of marketable securities
Less than 12 months in unrealized loss position - fair value	10,575	18,431
Less than 12 months in unrealized loss position - gross unrealized losses	(116)	(86)
12 months or more in unrealized loss position - fair value	14,970	16,430
12 months or more in unrealized loss position - gross unrealized losses	$ (30)	$ (69)

Investments (Details Textual)

Investments (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Investment [Line Items]
Net realized gains (losses) from the sale of marketable securities	$ 0	$ 1	$ 0	$ 1
Investments without readily determinable fair value, impairments recognized			0
Gain on step acquisition			$ 7,648	$ 0
Shyft [Member]
Investment [Line Items]
Investments without readily determinable fair value, description			the Company held shares of Series Seed Preferred Stock and Series B Preferred Stock of SHYFT Analytics, Inc. ("SHYFT"), purchased in private placements. These investments did not have a readily determinable fair value and were carried at original cost
Investments without readily determinable fair value, original cost					$ 5,100
Syapse [Member]
Investment [Line Items]
Investments without readily determinable fair value, description			The Company holds shares of Series D Preferred Stock of Syapse Inc. ("Syapse") 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		$ 3,000

Fair Value (Details)

Fair Value (Details) - Fair value, recurring [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Assets
Total cash and cash equivalents	$ 120,298	$ 237,325
Total marketable securities	357,079	426,008
Total financial assets	477,377	663,333
Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	1,351	3,993
Contingent consideration - long-term	581	2,012
Total financial liabilities	1,932	6,005
Cash [Member]
Assets
Total cash and cash equivalents	118,584	237,149
Money market funds [Member]
Assets
Total cash and cash equivalents	1,714	176
Commercial paper and corporate bonds [Member]
Assets
Total marketable securities	331,534	391,147
U.S. government agency debt securities [Member]
Assets
Total marketable securities	25,545	34,861
Level 1 [Member]
Assets
Total cash and cash equivalents	120,298	237,325
Total marketable securities	0	0
Total financial assets	120,298	237,325
Level 1 [Member] | Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	0	0
Contingent consideration - long-term	0	0
Total financial liabilities	0	0
Level 1 [Member] | Cash [Member]
Assets
Total cash and cash equivalents	118,584	237,149
Level 1 [Member] | Money market funds [Member]
Assets
Total cash and cash equivalents	1,714	176
Level 1 [Member] | Commercial paper and corporate bonds [Member]
Assets
Total marketable securities	0	0
Level 1 [Member] | U.S. government agency debt securities [Member]
Assets
Total marketable securities	0	0
Level 2 [Member]
Assets
Total cash and cash equivalents	0	0
Total marketable securities	357,079	426,008
Total financial assets	357,079	426,008
Level 2 [Member] | Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	0	0
Contingent consideration - long-term	0	0
Total financial liabilities	0	0
Level 2 [Member] | Cash [Member]
Assets
Total cash and cash equivalents	0	0
Level 2 [Member] | Money market funds [Member]
Assets
Total cash and cash equivalents	0	0
Level 2 [Member] | Commercial paper and corporate bonds [Member]
Assets
Total marketable securities	331,534	391,147
Level 2 [Member] | U.S. government agency debt securities [Member]
Assets
Total marketable securities	25,545	34,861
Level 3 [Member]
Assets
Total cash and cash equivalents	0	0
Total marketable securities	0	0
Total financial assets	0	0
Level 3 [Member] | Contingent consideration [Member]
Liabilities
Contingent consideration - short-term	1,351	3,993
Contingent consideration - long-term	581	2,012
Total financial liabilities	1,932	6,005
Level 3 [Member] | Cash [Member]
Assets
Total cash and cash equivalents	0	0
Level 3 [Member] | Money market funds [Member]
Assets
Total cash and cash equivalents	0	0
Level 3 [Member] | Commercial paper and corporate bonds [Member]
Assets
Total marketable securities	0	0
Level 3 [Member] | U.S. government agency debt securities [Member]
Assets
Total marketable securities	$ 0	$ 0

Fair Value (Details 1)

Fair Value (Details 1) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent consideration, fair value - beginning of period	$ 6,005
Contingent consideration, due to sellers	(4,080)
Contingent consideration, fair value adjustment	7
Contingent consideration, fair value - end of period	$ 1,932

Fair Value (Details Textual)

Fair Value (Details Textual) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
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] | Commercial paper and corporate bonds [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 2 [Member] | U.S. government agency debt securities [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%.

Acquisitions (Details)

Acquisitions (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 20, 2018	Feb. 17, 2017
Shyft [Member]
Business Acquisition [Line Items]
Effective date of acquisition	Jun. 20, 2018
Transaction description	the Company acquired all outstanding equity interests
Name of acquired entity	SHYFT
Description of acquired entity	a Waltham, Massachusetts provider of cloud data analytics for life sciences
Reason for business combination	With this acquisition, the Company expands its offerings to include commercial and real-world data analytics solutions that are designed specifically for the pharmaceutical and biotech industries
Total consideration	$ 196.5
Cash consideration, gross	183.8
Fair value of previous investment in acquired entity	$ 12.7
Cash and cash equivalents acquired			$ 4.7
Net tangible assets acquired (liabilities assumed), net			1.9
Deferred tax asset recognized			1.9
Provisional information, initial accounting incomplete, reasons	given the transaction's proximity to the end of the current reporting period, valuation of identified intangible assets is still in progress and allocation of the remaining $191.8 million of purchase price between intangible assets and goodwill is incomplete. The Company anticipates that this transaction will generate significant goodwill due to the skilled workforce of approximately 150 employees acquired and considerable synergies expected. As of June 30, 2018, the Company has recorded a provisional estimate based on observation of industry trends
Estimated intangible assets acquired			$ 40
Estimated goodwill recognized	151.8
Provisional information, initial accounting incomplete, items	The Company expects to finalize valuation and useful life determination for the acquired customer relationships, developed technology, non-competition agreements, and trade name during the third quarter of 2018. The purchase price and the allocation thereof are subject to change within the relevant one-year measurement period as a result of customary working capital adjustments.
CHITA and Mytrus [Member]
Business Acquisition [Line Items]
Transaction description		The Company acquired all outstanding equity interests
Name of acquired entity		CHITA and Mytrus
Reason for business combination		adding regulated document and standard operating procedure ("SOP") management, electronic trial master file ("eTMF"), and eConsent capabilities to its platform
Total consideration		$ 28.9
Cash consideration, gross		$ 23.2
Acquisition date fair value of contingent consideration liability				$ 5.7
CHITA [Member]
Business Acquisition [Line Items]
Effective date of acquisition		Feb. 17, 2017
Mytrus [Member]
Business Acquisition [Line Items]
Effective date of acquisition		Apr. 18, 2017

Goodwill and Intangible Asset45

Goodwill and Intangible Assets (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Changes in the carrying amount of goodwill
Balance as of beginning of period	$ 47,435
Additions related to acquisition	151,857
Purchase price adjustment	(422)
Foreign currency translation adjustments	(90)
Balance as of end of period	$ 198,780

Goodwill and Intangible Asset46

Goodwill and Intangible Assets (Details 1) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Intangible assets
Gross carrying amount	$ 69,148	$ 29,185
Accumulated amortization	(14,210)	(11,598)
Net carrying amount	54,938	17,587
Developed technology [Member]
Intangible assets
Gross carrying amount	44,407	24,436
Accumulated amortization	(11,152)	(8,883)
Net carrying amount	33,255	15,553
Customer relationships [Member]
Intangible assets
Gross carrying amount	24,481	4,489
Accumulated amortization	(2,907)	(2,595)
Net carrying amount	21,574	1,894
Non-competition agreements [Member]
Intangible assets
Gross carrying amount	260	260
Accumulated amortization	(151)	(120)
Net carrying amount	$ 109	$ 140

Goodwill and Intangible Asset47

Goodwill and Intangible Assets (Details 2) $ in Thousands	Jun. 30, 2018USD ($)
Annual amortization for the next five years
Remainder of year current year	$ 6,339
Next twelve months	12,486
Year two	11,742
Year three	11,472
Year four	8,877
Year five	4,022
Thereafter	$ 0

Debt (Details)

Debt (Details) - 1.00% convertible senior notes [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Components of convertible senior notes
Equity component net of equity issue costs	$ 60,222	$ 60,222
Principal amount	287,500	287,500
Unamortized discount	(1,646)	(8,661)
Unamortized debt issuance costs	(106)	(745)
Convertible senior notes, net carrying amount	$ 285,748	$ 278,094

Debt (Details 1)

Debt (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest expense on convertible senior notes
Amortization of debt issuance costs			$ 856	$ 639
Amortization of debt discount			7,015	6,607
1.00% convertible senior notes [Member]
Interest expense on convertible senior notes
Contractual interest expense	$ 719	$ 719	1,438	1,438
Amortization of debt issuance costs	320	320	639	639
Amortization of debt discount	3,534	3,328	7,015	6,607
Total interest expense	$ 4,573	$ 4,367	$ 9,092	$ 8,684
Convertible senior notes, effective interest rate during period	6.50%	6.50%	6.50%	6.50%

Debt (Details 2)

Debt (Details 2) - Term loans (under credit facility) [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Dec. 21, 2017
Debt Instrument [Line Items]
Principal amount	$ 98,750	$ 100,000	$ 100,000
Unamortized debt issuance costs	(1,942)	(2,159)
Net carrying amount	$ 96,808	$ 97,841

Debt (Details 3)

Debt (Details 3) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Amortization of debt issuance costs		$ 856	$ 639
Credit facility [Member]
Debt Instrument [Line Items]
Contractual interest expense	$ 811	1,559
Amortization of debt issuance costs	109	217
Unused commitment fee	209	409
Total interest expense	$ 1,129	$ 2,185

Debt (Details Textual)

Debt (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017	Dec. 21, 2017
Debt Instrument [Line Items]
Closing price of the Company's common stock	$ 80.56
1.00% convertible senior notes [Member]
Debt Instrument [Line Items]
Contractual interest rate	1.00%
Maturity description	The Notes mature on August 1, 2018 unless earlier repurchased or converted. Until close of business on the business day immediately preceding the maturity date, holders may convert their Notes at any time;
If-converted value in excess of principal	$ 111,500
Principal amount	$ 287,500	$ 287,500
Approximate remaining life	1 month
1.00% convertible senior notes [Member] | Level 2 [Member]
Debt Instrument [Line Items]
Approximate fair value	$ 395,700	336,400
Credit facility [Member]
Debt Instrument [Line Items]
Approximate remaining life	54 months
Covenant compliance	The Company was in compliance with all financial covenants related to the Credit Facility
Term loans (under credit facility) [Member]
Debt Instrument [Line Items]
Contractual interest rate	3.465%
Maturity 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	$ 98,750	100,000	$ 100,000
Current maturities of long-term debt	4,900	$ 5,000
Revolver (under credit facility) [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 400,000
Remaining borrowing capacity	$ 400,000
Unused commitment fee rate	0.20%

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Components of stock-based compensation expense
Total stock-based compensation	$ 15,190	$ 12,750	$ 28,404	[1]	$ 23,142	[1]
Stock options [Member]
Components of stock-based compensation expense
Total stock-based compensation	522	938	1,094		1,855
Restricted stock awards and units [Member]
Components of stock-based compensation expense
Total stock-based compensation	9,024	7,769	16,891		14,688
Performance-based restricted stock units [Member]
Components of stock-based compensation expense
Total stock-based compensation	3,932	3,074	7,159		4,702
Employee stock purchase plan [Member]
Components of stock-based compensation expense
Total stock-based compensation	$ 1,712	$ 969	$ 3,260		$ 1,897
[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 (Det54

Stock-Based Compensation (Details 1) - Stock options [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted-average Black-Scholes assumptions used to estimate fair value of stock options granted
Expected volatility	42.00%	43.00%	42.00%	44.00%
Expected term	4 years 9 months 10 days	6 years	4 years 9 months 10 days	6 years
Risk-free interest rate	2.82%	2.02%	2.82%	2.07%
Dividend yield	0.00%	0.00%	0.00%	0.00%

Stock-Based Compensation (Det55

Stock-Based Compensation (Details 2) - Stock options [Member] $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Summary of activities and changes in stock option plans
Number of shares outstanding at beginning of period | shares	1,511
Weighted-average exercise price outstanding at beginning of period | $ / shares	$ 22.72
Number of shares granted | shares	35
Weighted-average exercise price granted | $ / shares	$ 72.27
Number of shares exercised | shares	(248)
Weighted-average exercise price exercised | $ / shares	$ 25.62
Number of shares forfeited | shares	(34)
Weighted-average exercise price forfeited | $ / shares	$ 45.55
Number of shares expired | shares	0
Weighted-average exercise price expired | $ / shares	$ 0
Number of shares outstanding at end of period | shares	1,264
Weighted-average exercise price outstanding at end of period | $ / shares	$ 22.91
Weighted average remaining contractual term outstanding at end of period	3 years 10 months 18 days
Aggregate intrinsic value outstanding at end of period | $	$ 72,894
Number of shares exercisable at end of period | shares	1,092
Weighted-average exercise price exercisable at end of period | $ / shares	$ 17.45
Weighted average remaining contractual term exercisable at end of period	3 years 1 month 27 days
Aggregate intrinsic value exercisable at end of period | $	$ 68,942
Number of shares vested and expected to vest at end of period | shares	1,252
Weighted-average exercise price vested and expected to vest at end of period | $ / shares	$ 22.52
Weighted average remaining contractual term vested and expected to vest at end of period	3 years 10 months
Aggregate intrinsic value vested and expected to vest at end of period | $	$ 72,657

Stock-Based Compensation (Det56

Stock-Based Compensation (Details 3) - Restricted stock awards and units [Member] shares in Thousands	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Summary of time-based nonvested restricted stock awards and units
Nonvested number of shares/units at beggining of period | shares	1,754
Nonvested weighted-average grant-date fair value at beginning of period | $ / shares	$ 48.45
Granted number of shares | shares	982
Granted weighted-average grant-date fair value | $ / shares	$ 72.56
Vested number of shares/units | shares	(554)
Vested weighted-average grant-date fair value | $ / shares	$ 46.99
Forfeited number of shares/units | shares	(191)
Forfeited weighted-average grant-date fair value | $ / shares	$ 50.03
Nonvested number of shares/units at end of period | shares	1,991
Nonvested weighted-average grant-date fair value at end of period | $ / shares	$ 60.60

Stock-Based Compensation (Det57

Stock-Based Compensation (Details 4) - Performance-based restricted stock units [Member] - TSR [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Assumptions used to estimate fair value of TSR PBRSUs
Expected volatility - Medidata	36.00%	42.00%	37.00%	42.00%
Expected volatility - Comparison index	43.00%	43.00%	42.00%	43.00%
Expected term	2 years 8 months 10 days	2 years 10 months 5 days	2 years 10 months 7 days	2 years 10 months 5 days
Risk-free interest rate	2.58%	1.40%	2.37%	1.40%
Dividend yield	0.00%	0.00%	0.00%	0.00%

Stock-Based Compensation (Det58

Stock-Based Compensation (Details 5) - Performance-based restricted stock units [Member] shares in Thousands	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	736
Nonvested weighted-average grant-date fair value at beginning of period | $ / shares	$ 62.96
Granted number of units (based on performance at 100% of targeted levels)	246
Granted weighted-average grant-date fair value | $ / shares	$ 85.92
Adjustment due to expected performance	181
Adjustment due to expected performance weighted average grant date fair value | $ / shares	$ 78.54
Vested number of shares/units	(120)
Vested weighted-average grant-date fair value | $ / shares	$ 69.92
Forfeited number of shares/units	(1)
Forfeited weighted-average grant-date fair value | $ / shares	$ 77.64
Nonvested number of shares/units at end of period	1,042
Nonvested weighted-average grant-date fair value at end of period | $ / shares	$ 70.27
Net income [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	110
Granted number of units (based on performance at 100% of targeted levels)	122
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	232
TSR [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	613
Granted number of units (based on performance at 100% of targeted levels)	122
Adjustment due to expected performance	171
Vested number of shares/units	(120)
Forfeited number of shares/units	0
Nonvested number of shares/units at end of period	786
Other goals [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	13
Granted number of units (based on performance at 100% of targeted levels)	2
Adjustment due to expected performance	10
Vested number of shares/units	0
Forfeited number of shares/units	(1)
Nonvested number of shares/units at end of period	24

Stock-Based Compensation (Det59

Stock-Based Compensation (Details 6) - Employee stock purchase plan [Member]	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted-average Black-Scholes assumptions used to estimate fair value of ESPP shares
Expected volatility	37.00%	39.00%	37.00%	39.00%
Expected term	1 year 8 months 12 days	1 year 5 months 27 days	1 year 8 months 12 days	1 year 5 months 27 days
Risk-free interest rate	1.09%	0.62%	1.09%	0.62%
Dividend yield	0.00%	0.00%	0.00%	0.00%

Stock-Based Compensation (Det60

Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock based compensation (Textual) [Abstract]
Incremental expense associated with equity modifications	$ 200	$ 0	$ 400	$ 100
Stock options [Member]
Stock based compensation (Textual) [Abstract]
Weighted-average grant-date fair value of stock options granted	$ 28.93	$ 25.47	$ 28.93	$ 25.37
Total intrinsic value of stock options exercised	$ 3,800	$ 4,000	$ 11,400	$ 8,000
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	3,900		$ 3,900
Weighted-average remaining period over which cost is expected to be recognized			2 years 5 months 15 days
Restricted stock awards and units [Member]
Stock based compensation (Textual) [Abstract]
Total fair value of shares vested	5,700	4,700	$ 37,300	31,000
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	107,000		$ 107,000
Weighted-average remaining period over which cost is expected to be recognized			2 years 7 months 25 days
Performance-based restricted stock units [Member]
Stock based compensation (Textual) [Abstract]
Total fair value of shares vested	0	$ 0	$ 8,100	$ 5,100
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 30,300		$ 30,300
Weighted-average remaining period over which cost is expected to be recognized			1 year 8 months 20 days
Target number of performance-based restricted stock units granted during the period		0
Performance-based restricted stock units [Member] | TSR [Member]
Stock based compensation (Textual) [Abstract]
Target number of performance-based restricted stock units granted during the period	6		122	132
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, 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		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.	market conditions based on the Company's TSR relative to that of the Russell 2000 Index over the three-year period ending December 31, 2019, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares
Performance-based restricted stock units [Member] | Other goals [Member]
Stock based compensation (Textual) [Abstract]
Award terms	performance conditions based on achievement of certain individual and team objectives.		performance conditions based on achievement of certain individual and team objectives.
Performance-based restricted stock units [Member] | Net income [Member]
Stock based compensation (Textual) [Abstract]
Target number of performance-based restricted stock units granted during the period	5		122	132
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.		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, 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	performance conditions based on the compound annual growth rate of net income over the three-year period ending December 31, 2019, vesting in full in three years with the number of shares ultimately earned ranging from zero to 200% of the target number of shares.
Employee stock purchase plan [Member]
Stock based compensation (Textual) [Abstract]
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 2,200		$ 2,200
Weighted-average remaining period over which cost is expected to be recognized			1 year 2 months 22 days
Shares issued during period under employee stock purchase plan	150	103	150	103
Weighted-average purchase price of shares issued during period under employee stock purchase plan	$ 43.04	$ 40.50	$ 43.04	$ 40.50

Accumulated Other Comprehensi61

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated other comprehensive income
Balance as of beginning of period			$ (3,377)
Other comprehensive income (loss), net of tax	$ (1,415)	$ 958	(1,113)	$ 1,450
Balance as of end of period	(4,490)		(4,490)
Unrealized gains (losses) on available for sale securities
Accumulated other comprehensive income
Balance as of beginning of period			(918)
Other comprehensive income (loss), net of tax			(429)
Balance as of end of period	(1,347)		(1,347)
Foreign currency translation adjustments
Accumulated other comprehensive income
Balance as of beginning of period			(2,459)
Other comprehensive income (loss), net of tax			(684)
Balance as of end of period	$ (3,143)		$ (3,143)

Accumulated Other Comprehensi62

Accumulated Other Comprehensive Income (Details Textual) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassifications from accumulated other comprehensive income	$ 0	$ 1

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Numerator
Net income	$ 16,589	$ 7,541	[1],[2]	$ 26,914	$ 17,521	[1],[2]
Denominator for basic earnings per share:
Weighted average common shares outstanding	57,448	56,433		57,252	56,254
Dilutive potential common shares:
Stock options	866	1,001		897	976
Restricted stock awards and units	612	798		752	835
Performance-based restricted stock units	610	625		586	560
Employee stock purchase plan	220	149		181	114
Convertible senior notes	1,118	829		896	312
Weighted average common shares outstanding with assumed conversion	60,874	59,835		60,564	59,051
Basic earnings per share	$ 0.29	$ 0.13	[2]	$ 0.47	$ 0.31	[2]
Diluted earnings per share	$ 0.27	$ 0.13	[2]	$ 0.44	$ 0.30	[2]
[1]	The condensed consolidated statements of comprehensive income for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."
[2]	The condensed consolidated statements of operations for the three and six months ended June 30, 2017 have been recast to reflect the Company's January 1, 2018 full retrospective adoption of ASC 606. For additional details, see Note 1, "Summary of Significant Accounting Policies — Recently Adopted Accounting Pronouncements."

Earnings Per Share (Details 1)

Earnings Per Share (Details 1) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Antidilutive common stock equivalents excluded from the calculation of diluted earnings per share
Antidilutive shares excluded from calculation of diluted earnings (loss) per share	197	370	192	487
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	79	94	78	202
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	34	1	30	10
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	0	0	0	0
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	84	275	84	275

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Income Taxes (Textual) [Abstract]
Gross unrecognized tax benefits	$ 4.1	$ 4.1
Changes in tax position	$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details)	6 Months Ended
	Jun. 30, 2018
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.
Wire transaction claim description	In September 2014, the Company was the victim of a crime involving the transfer of $4.8 million to an overseas account. As a result, the Company recorded charges of $4.9 million and $0.9 million to its operating costs and expenses in the third and fourth quarters of 2014, respectively, for the loss and related investigation costs incurred. The Company filed an insurance claim for its loss, and its insurer, Federal Insurance Co. ("Federal"), denied coverage. The Company commenced legal action, alleging that Federal had wrongly denied coverage. On July 21, 2017, the United States District Court for the Southern District of New York granted the Company's motion for summary judgment, and denied Federal's motion. In light of this ruling, the Company recognized the probable recovery of the originally recorded $4.8 million loss as a credit to its operating costs and expenses in the third quarter of 2017. Federal filed a Notice of Appeal with the United States Court of Appeals for the Second Circuit ("the Court") on August 11, 2017. On July 6, 2018, the Court affirmed the Company's judgment against Federal, awarding the Company a total of $5.8 million, which includes interest. On July 20, 2018, Federal filed a Petition for Panel Rehearing and Rehearing En Banc, which is currently pending with the Court.

Subsequent Event (Details)

Subsequent Event (Details) - Subsequent Event [Member]	9 Months Ended
	Sep. 30, 2018shares
Subsequent Event [Line Items]
Subsequent event, description	The Notes matured on August 1, 2018, and the Company received notices of conversion for substantially all of the outstanding Notes prior to the maturity date. Pursuant to its election, the Company settled the $287.5 million principal amount of the Notes in cash and the conversion premium in shares of its common stock. The Company issued 1,439,704 shares of common stock in settlement of the premium, determined by a calculation based on the volume-weighted average price of the Company's common stock over the 40 trading-day observation period beginning on and including June 1, 2018, as specified in the indenture governing the Notes.
Subsequent event, date	Aug. 1, 2018
Debt conversion, shares issued	1,439,704