Medidata Solutions 10-Q 8 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	May 01, 2017
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	Mar. 31, 2017
Document fiscal period focus	Q1
Document fiscal year focus	2,017
Current fiscal year end date	--12-31
Entity filer category	Large Accelerated Filer
Entity common stock, shares outstanding		58,358,341

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 90,422	$ 93,519
Marketable securities	274,602	281,285
Accounts receivable, net of allowance for doubtful accounts	102,491	115,216
Prepaid commission expense	2,550	1,842
Prepaid expenses and other current assets	24,472	20,382
Deferred income taxes	0	6,536
Total current assets	494,537	518,780
Restricted cash	5,511	5,760
Furniture, fixtures and equipment, net	63,284	58,461
Marketable securities- long-term	148,359	140,418
Goodwill	39,075	30,780
Intangible assets, net	13,036	5,090
Deferred income taxes- long-term	43,276	40,415
Other assets	20,350	18,181
Total assets	827,428	817,885
Current liabilities:
Accounts payable	6,699	6,202
Accrued payroll and other compensation	16,034	29,260
Accrued expenses and other	23,829	20,958
Deferred revenue	80,122	75,911
Total current liabilities	126,684	132,331
Noncurrent liabilities:
1.00% convertible senior notes, net	266,999	263,401
Deferred revenue, less current portion	1,607	1,703
Deferred tax liabilities	124	322
Other long-term liabilities	20,642	18,138
Total noncurrent liabilities	289,372	283,564
Total liabilities	416,056	415,895
Commitments and contingencies
Stockholders' equity:
Preferred stock	0	0
Common stock	622	614
Additional paid-in capital	431,479	418,497
Treasury stock	(127,822)	(114,204)
Accumulated other comprehensive loss	(4,784)	(5,276)
Retained earnings	111,877	102,359
Total stockholders' equity	411,372	401,990
Total liabilities and stockholders' equity	$ 827,428	$ 817,885

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accounts receivable, allowance for doubtful accounts	$ 1,650	$ 1,041
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	62,246	61,393
Common stock, shares outstanding	58,254	57,733
Treasury stock, shares	3,992	3,660

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Revenues
Subscription		$ 107,070	$ 89,968
Professional services		19,751	14,270
Total revenues		126,821	104,238
Cost of revenues
Subscription		17,129	14,329
Professional services		13,485	10,339
Total cost of revenues	[1],[2]	30,614	24,668
Gross profit		96,207	79,570
Operating costs and expenses:
Research and development	[2]	29,937	28,228
Sales and marketing	[1],[2]	30,109	25,458
General and administrative	[2]	23,988	19,246
Total operating costs and expenses		84,034	72,932
Operating income		12,173	6,638
Interest and other income (expense):
Interest expense		(4,327)	(4,127)
Interest income		1,171	872
Other income (expense), net		0	(4)
Total interest and other expense, net		(3,156)	(3,259)
Income before income taxes		9,017	3,379
Provision for income taxes		(501)	(1,196)	[3]
Net income		$ 9,518	$ 4,575	[3],[4]
Earnings per share:
Basic		$ 0.17	$ 0.08	[3]
Diluted		$ 0.16	$ 0.08	[3]
Weighted average common shares outstanding:
Basic		56,072	55,119	[3]
Diluted		58,083	56,589	[3]
Total stock-based compensation	[2]	$ 10,321	$ 10,250
Total amortization of intangible assets	[1]	537	103
Cost of revenues
Weighted average common shares outstanding:
Total stock-based compensation	[2]	1,169	1,210
Total amortization of intangible assets	[1]	454	79
Research and development
Weighted average common shares outstanding:
Total stock-based compensation	[2]	2,835	2,194
Sales and marketing
Weighted average common shares outstanding:
Total stock-based compensation	[2]	1,175	1,877
Total amortization of intangible assets	[1]	83	24
General and administrative
Weighted average common shares outstanding:
Total stock-based compensation	[2]	$ 5,142	$ 4,969
[1]	Amortization of intangible assets included in cost of revenues and operating costs and expenses
[2]	Stock-based compensation expense included in cost of revenues and operating costs and expenses
[3]	Prior period recast to reflect the Company's early adoption of Accounting Standards Update No. 2016-09 in the third quarter of 2016
[4]	As a result of the Company's 2016 mid-year early adoption of Accounting Standards Update No. 2016-09, which requires excess tax benefit on equity awards to be presented as an operating activity, the consolidated statement of cash flows for the three months ended March 31, 2016 has been adjusted to reflect an offsetting increase of $1,341 thousand to net cash provided by operating activities and net cash used in financing activities

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 9,518	$ 4,575	[1],[2]
Other comprehensive income (loss):
Foreign currency translation adjustments	423	(87)
Unrealized gain (loss) on marketable securities	112	1,308
Other comprehensive income (loss)	535	1,221
Income tax effect of unrealized gain or loss on marketable securities	(43)	0
Other comprehensive income (loss), net of tax	492	1,221
Comprehensive income (loss), net of tax	$ 10,010	$ 5,796	[2]
[1]	As a result of the Company's 2016 mid-year early adoption of Accounting Standards Update No. 2016-09, which requires excess tax benefit on equity awards to be presented as an operating activity, the consolidated statement of cash flows for the three months ended March 31, 2016 has been adjusted to reflect an offsetting increase of $1,341 thousand to net cash provided by operating activities and net cash used in financing activities
[2]	Prior period recast to reflect the Company's early adoption of Accounting Standards Update No. 2016-09 in the third quarter of 2016

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income		$ 9,518	$ 4,575	[1],[2]
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of intangible assets and depreciation		4,476	3,217
Stock-based compensation	[3]	10,321	10,250
Amortization of discounts or premiums on marketable securities		413	983
Deferred income taxes		1,355	1,187	[1]
Amortization of debt issuance costs		319	319
Amortization of debt discount		3,279	3,089
Provision for doubtful accounts		680	371
Loss on fixed asset disposal		(2)	4
Changes in operating assets and liabilities:
Accounts receivable		12,045	4,635
Prepaid commission expense		(1,843)	(2,738)
Prepaid expenses and other current assets		(6,791)	1,199
Other assets		1,712	(2,590)
Accounts payable		130	(1,297)
Accrued payroll and other compensation		(15,557)	(10,052)
Accrued expenses and other		(2,397)	238
Deferred revenue		4,090	3,134
Other long-term liabilities		737	(2,720)
Net cash provided by (used in) operating activities		22,485	13,804	[1]
Cash flows from investing activities:
Purchases of furniture, fixtures and equipment		(6,790)	(7,589)
Purchases of available-for-sale securities		(81,985)	(28,815)
Proceeds from sale of available-for-sale securities		80,426	69,352
Acquisition of business, net of cash acquired		(8,702)	0
Net cash provided by (used in) investing activities		(17,051)	32,948
Cash flows from financing activities:
Proceeds from exercise of stock options		2,597	194
Proceeds from employee stock purchase plan		2,090	1,819
Acquisition of treasury stock		(13,617)	(10,831)
Net cash provided by (used in) financing activities		(8,930)	(8,818)	[1]
Effect of exchange rate changes on cash, cash equivalents and restricted cash		150	173
Net increase (decrease) in cash, cash equivalents and restricted cash		(3,346)	38,107
Cash, cash equivalents and restricted cash - beginning of period	[4]	99,279	55,472
Cash, cash equivalents and restricted cash - end of period	[4]	95,933	93,579
Cash paid during the period for:
Interest		1,438	1,438
Income taxes		640	794
Noncash activities:
Furniture, fixtures, and equipment acquired but not yet paid for at period-end		2,743	951
Contingent consideration associated with acquisition		$ 5,697	$ 0
[1]	As a result of the Company's 2016 mid-year early adoption of Accounting Standards Update No. 2016-09, which requires excess tax benefit on equity awards to be presented as an operating activity, the consolidated statement of cash flows for the three months ended March 31, 2016 has been adjusted to reflect an offsetting increase of $1,341 thousand to net cash provided by operating activities and net cash used in financing activities
[2]	Prior period recast to reflect the Company's early adoption of Accounting Standards Update No. 2016-09 in the third quarter of 2016
[3]	Stock-based compensation expense included in cost of revenues and operating costs and expenses
[4]	As a result of the Company's early adoption of Accounting Standards Update No. 2016-18, the consolidated statements of cash flows have been adjusted to include restricted cash in beginning-of-period and end-of-period cash. Beginning- and end-of-period cash, cash equivalents and restricted cash for the three months ended March 31, 2016 include $154 thousand of short-term restricted cash; the Company records short-term restricted cash in prepaid expenses and other current assets on its consolidated balance sheets

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Medidata Solutions, Inc., together with its consolidated subsidiaries (collectively, the "Company"), is the leading global provider of cloud-based solutions for clinical research in life sciences, offering platform technology that transforms clinical development and increases the value of its customers' research investments. The Company was organized as a New York corporation in June 1999 and reincorporated as a Delaware corporation in May 2000. Except to the extent updated or described below, the Company’s significant accounting policies as of March 31, 2017 are the same as those at December 31, 2016 , which are included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2016 , filed with the Securities and Exchange Commission (“SEC”) on February 28, 2017 . Basis of Presentation — The accompanying interim condensed consolidated balance sheets as of March 31, 2017 and December 31, 2016 , the condensed consolidated statements of operations for the three months ended March 31, 2017 and 2016 , the condensed consolidated statements of comprehensive income for the three months ended March 31, 2017 and 2016 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2017 and 2016 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, 2016 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2017 . The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments consisting of normal recurring accruals considered necessary to present fairly the Company’s financial position as of March 31, 2017 , results of its operations for the three months ended March 31, 2017 and 2016 , comprehensive income for the three months ended March 31, 2017 and 2016 , and cash flows for the three months ended March 31, 2017 and 2016 . The results of operations for the three months ended March 31, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 . 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. Accounts Receivable — Accounts receivable are recorded at original invoice amount less an allowance that management believes will be adequate to absorb estimated losses on uncollectible accounts. This allowance is based on an evaluation of the collectability of accounts receivable and prior bad debt experience. Accounts receivable are written off when deemed uncollectible. Unbilled receivables consist of revenue recognized in excess of billings, substantially all of which is expected to be billed and collected within one year. As of March 31, 2017 and December 31, 2016 , unbilled accounts receivable of $14.7 million and $14.1 million , respectively, were included in accounts receivable on the Company's consolidated balance sheets. In general, there is a direct relationship between the Company's accounts receivable balance and its transaction volume. Recently Adopted Accounting Pronouncements — In November 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2015-17, Income Taxes: Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred income taxes by requiring that all deferred tax assets and liabilities be classified as noncurrent in the consolidated balance sheets. ASU No. 2015-17 is effective for annual reporting periods beginning after December 15, 2016 and interim periods within those annual periods, and may be applied either prospectively or retrospectively to all periods presented. The Company adopted ASU No. 2015-17 prospectively on January 1, 2017, and the adoption did not have a material impact on its consolidated financial statements, aside from a balance sheet reclassification from short-term to long-term deferred income taxes. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory, which requires entities to recognize the income tax consequences of intra-entity transfers of assets other than inventory when those transfers occur. ASU No. 2016-16 is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual periods. The Company early adopted ASU No. 2016-16 on January 1, 2017, and the adoption had no impact on its consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash , which requires entities to include restricted cash in cash and cash equivalents when reconciling beginning-of-period and end-of-period cash in the statement of cash flows. ASU No. 2016-18 is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. The Company early adopted ASU No. 2016-18 retrospectively on January 1, 2017 and the adoption did not have a material impact on its consolidated financial statements, aside from changes in presentation. 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.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2017
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 Second Amended and Restated 2009 Long-Term Incentive Plan (the “2009 Plan”). Under the provisions of the 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 for future reissuance. During the three months ended March 31, 2017 and 2016 , the Company withheld 242,998 shares at an average price of $56.04 and 257,878 shares at an average price of $33.57 , respectively, in connection with the vesting of equity awards. Nonvested restricted stock awards forfeited by plan participants are transferred to the Company's treasury stock at par. During the three months ended March 31, 2017 and 2016 , 89,386 and 54,161 forfeited shares, respectively, were transferred to treasury stock at their par value of $0.01 .

Investments

Investments	3 Months Ended
	Mar. 31, 2017
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 consolidated balance sheets. The following tables provide the Company’s marketable securities by security type as of March 31, 2017 and December 31, 2016 (in thousands): As of March 31, 2017 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 389,100 $ 2 $ (713 ) $ 388,389 U.S. government agency debt securities 34,636 — (64 ) 34,572 Total $ 423,736 $ 2 $ (777 ) $ 422,961 As of December 31, 2016 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 389,459 $ 4 $ (827 ) $ 388,636 U.S. government agency debt securities 33,132 — (65 ) 33,067 Total $ 422,591 $ 4 $ (892 ) $ 421,703 Contractual maturities of the Company’s marketable securities as of March 31, 2017 and December 31, 2016 are summarized as follows (in thousands): As of March 31, 2017 As of December 31, 2016 Cost Estimated Fair Value Cost Estimated Fair Value Due in one year or less $ 275,007 $ 274,602 $ 281,591 $ 281,285 Due in one to five years 148,729 148,359 141,000 140,418 Total $ 423,736 $ 422,961 $ 422,591 $ 421,703 At March 31, 2017 , the Company had $0.8 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 March 31, 2017 are temporary in nature. Accordingly, the Company did not consider its investments in marketable securities to be other-than-temporarily impaired as of March 31, 2017 . 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 March 31, 2017 and December 31, 2016 (in thousands): In Loss Position for Less than 12 Months As of March 31, 2017 As of December 31, 2016 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 351,361 $ (685 ) $ 299,708 $ (771 ) U.S. government agency debt securities 27,454 (56 ) 28,273 (59 ) Total $ 378,815 $ (741 ) $ 327,981 $ (830 ) In Loss Position for More than 12 Months As of March 31, 2017 As of December 31, 2016 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 35,021 $ (28 ) $ 68,158 $ (56 ) U.S. government agency debt securities 4,792 (8 ) 4,794 (6 ) Total $ 39,813 $ (36 ) $ 72,952 $ (62 ) During the three months ended March 31, 2017 and 2016 , the Company recorded an insignificant amount of net realized gains from the sale of marketable securities. Cost Method Investment The Company holds shares of Series B Preferred Stock of SHYFT Analytics, Inc. ("SHYFT"), purchased via a private placement. This investment is accounted for under the cost method and is included in other assets on the Company's consolidated balance sheet as of March 31, 2017 at its purchase price of $4.0 million .

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUE The following table summarizes, as of March 31, 2017 and December 31, 2016 , 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, 2016 (in thousands): As of March 31, 2017 As of December 31, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 90,174 $ — $ — $ 90,174 $ 93,384 $ — $ — $ 93,384 Money market funds 248 — — 248 135 — — 135 Total cash and cash equivalents 90,422 — — 90,422 93,519 — — 93,519 Commercial paper and corporate bonds — 388,389 — 388,389 — 388,636 — 388,636 U.S. government agency debt securities — 34,572 — 34,572 — 33,067 — 33,067 Total marketable securities — 422,961 — 422,961 — 421,703 — 421,703 Total financial assets measured at fair value on a recurring basis $ 90,422 $ 422,961 $ — $ 513,383 $ 93,519 $ 421,703 $ — $ 515,222 Contingent consideration – short-term $ — $ — $ 3,930 $ 3,930 $ — $ — $ — $ — Contingent consideration – long-term — — 1,767 1,767 — — — — Total financial liabilities measured at fair value on a recurring basis $ — $ — $ 5,697 $ 5,697 $ — $ — $ — $ — Investments in commercial paper, corporate bonds, and U.S. government agency debt securities have been classified as Level 2 as they are valued using quoted prices in less active markets or other directly or indirectly observable inputs. Fair values of corporate bonds and U.S. government agency debt securities were derived from a consensus or weighted-average price based on input of market prices from multiple sources at each reporting period. With regard to commercial paper, all of the securities had high credit ratings and one year or less to maturity; therefore, fair value was derived from accretion of purchase price to face value over the term of maturity or quoted market prices for similar instruments if available. During the three months ended March 31, 2017 and 2016 , there were no transfers of financial assets between Level 1 and Level 2. Contingent consideration liabilities associated with acquisition-related earn-out payments 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 short-term contingent consideration, which is related to the achievement of a technical milestone, has been estimated using situation-based modeling, which considers the probability-weighted present value of the expected payout amount. Significant assumptions include the Company's expectations with regard to the likelihood and timing of achievement of the related technical milestone and a discount rate of 2.9%. The fair value of long-term contingent consideration, which is related to achievement of revenue targets, has been estimated using a Monte Carlo simulation to simulate future performance of the acquired business under a risk-neutral framework; significant assumptions include a risk-adjusted discount rate of 10.2% and revenue volatility of 8.0%. Short-term and long-term contingent consideration are recorded in accrued expenses and other and other long-term liabilities, respectively, on the Company's consolidated balance sheet as of March 31, 2017 . The carrying amounts of all other current financial assets and current financial liabilities reflected in the consolidated balance sheets approximate fair value due to their short-term nature.

Acquisition

Acquisition	3 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
ACQUISITION	ACQUISITION On February 17, 2017 , the Company acquired all outstanding equity interests in CHITA Inc. ("CHITA") and its parent company, Daybreak Information Technologies Holdings Limited. CHITA provides regulated content management for the life sciences industry. With this acquisition, the Company adds regulated document and standard operating procedure ("SOP") management to its portfolio of offerings, and expects to add an electronic trial master file ("eTMF") solution built on CHITA's technology in the near future. The total purchase consideration of $14.7 million consisted of initial cash consideration of $9.0 million and additional contingent consideration that had a fair value of $5.7 million as of the acquisition date. In connection with this acquisition, the Company recognized $0.1 million in net tangible assets, $8.5 million in finite-lived intangible assets, and a deferred tax liability of $2.1 million , resulting in the recognition of $8.2 million in goodwill. Intangible assets acquired were as follows (in thousands): Acquisition Date Fair Value Weighted-Average Useful Life Developed technology $ 8,423 5 years Non-competition agreements 60 4 years Total $ 8,483 The Company does not consider this acquisition to be significant to its financial condition or results of operations; its consolidated results of operations for the three months ended March 31, 2017 include the revenues and expenses of CHITA since the date of acquisition.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS The change in the carrying amount of goodwill during the three months ended March 31, 2017 was as follows (in thousands): Balance as of January 1, 2017 $ 30,780 Additions related to acquisition 8,248 Foreign currency translation adjustments 47 Balance as of March 31, 2017 $ 39,075 Total intangible assets are summarized as follows (in thousands): As of March 31, 2017 As of December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 17,153 $ (5,568 ) $ 11,585 $ 8,714 $ (5,098 ) $ 3,616 Customer relationships 3,570 (2,254 ) 1,316 3,566 (2,176 ) 1,390 Non-competition agreements 210 (75 ) 135 150 (66 ) 84 Total $ 20,933 $ (7,897 ) $ 13,036 $ 12,430 $ (7,340 ) $ 5,090 Future amortization of intangible assets is expected to be as follows (in thousands): Remainder of year ending December 31, 2017 $ 2,447 Years ending December 31, 2018 3,187 2019 2,930 2020 2,198 2021 1,932 2022 342 Total $ 13,036

Debt

Debt	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
DEBT	DEBT The Company's 1.00% convertible senior notes (the "Notes"), issued in August 2013, consisted of the following components as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Equity component, net of equity issue costs $ 60,222 $ 60,222 Liability component: Principal 287,500 287,500 Less: unamortized debt discount (18,797 ) (22,076 ) Less: unamortized debt issuance costs (1,704 ) (2,023 ) Net carrying amount $ 266,999 $ 263,401 As of March 31, 2017 and December 31, 2016 , the estimated fair value of the Notes was $326.6 million and $314.4 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. As of March 31, 2017 , the Notes are not convertible. Based on the closing price of the Company's common stock as of March 31, 2017 of $57.69 , which is less than the Notes' initial conversion price of $58.05 , the if-converted value of the Notes was less than their principal amount. As of March 31, 2017 , the remaining life of the Notes is approximately 16 months . The following table sets forth total interest expense recognized related to the Notes for the three months ended March 31, 2017 and 2016 (in thousands except percentages): Three Months Ended March 31, 2017 2016 Contractual interest expense $ 719 $ 719 Amortization of debt issuance costs 319 319 Amortization of debt discount 3,279 3,089 Total $ 4,317 $ 4,127 Effective interest rate 6.5 % 6.5 %

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION For the three months ended March 31, 2017 and 2016 , the components of stock-based compensation expense were as follows (in thousands): Three Months Ended March 31, 2017 2016 Stock options $ 917 $ 1,055 Restricted stock awards and units 6,919 5,478 Performance-based restricted stock units 1,628 2,634 Employee stock purchase plan 928 1,083 Total stock-based compensation (1) $ 10,392 $ 10,250 (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 Options The fair value of each stock option granted during the three months ended March 31, 2017 and 2016 was estimated on the date of grant using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended March 31, 2017 2016 Expected volatility 44 % 43 % Expected life 6 years 6 years Risk-free interest rate 2.09 % 1.50 % Dividend yield — — The following table summarizes the status of the Company's stock options as of March 31, 2017 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2017 1,793 $23.39 Granted 57 56.74 Exercised (117 ) 22.20 Forfeited (26 ) 45.66 Expired (7 ) 58.92 Outstanding at March 31, 2017 1,700 $24.10 5.06 $57,328 Exercisable at March 31, 2017 1,347 $18.08 4.13 $53,538 Vested and expected to vest at March 31, 2017 1,663 $23.60 4.97 $56,900 The weighted-average grant-date fair value of stock options granted during the three months ended March 31, 2017 and 2016 was $25.33 and $16.94 , respectively. The total intrinsic value of stock options exercised during the three months ended March 31, 2017 and 2016 was $4.0 million and $0.7 million , respectively. The total fair value of stock options vested during the three months ended March 31, 2017 and 2016 was $1.1 million and $0.8 million , respectively. As of March 31, 2017 , there was $6.7 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 2.60 years . R estricted Stock Awards and Units The following table summarizes the status of the Company’s nonvested time-based RSAs and RSUs as of March 31, 2017 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Grant-Date Fair Value Nonvested at January 1, 2017 1,850 $40.89 Granted 648 56.10 Vested (468 ) 37.82 Forfeited (89 ) 40.97 Nonvested at March 31, 2017 1,941 $46.70 The total fair value of RSAs and RSUs vested during the three months ended March 31, 2017 and 2016 was $26.3 million and $9.4 million , respectively. As of March 31, 2017 , there was $82.1 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 2.94 years . Performance-Based Restricted Stock Units During the three months ended March 31, 2017 , the Company granted: (1) 132 thousand PBRSUs ("2017 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, 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. During the three months ended March 31, 2016 , the Company granted 223 thousand PBRSUs ("2016 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, 2018, 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 insignificant number of other PBRSUs with performance conditions based on achievement of certain individual performance objectives. The fair value of PBRSUs with market conditions granted during the three months ended March 31, 2017 and 2016 was estimated as of the date of grant using a Monte Carlo valuation model with the following weighted average assumptions: 2017 TSR PBRSUs 2016 TSR PBRSUs Expected volatility - Medidata 42 % 48 % Expected volatility - comparison index 43 % 43 % Expected life 2.85 years 2.84 years Risk-free interest rate 1.40 % 0.91 % Dividend yield — — The following table summarizes the status of the Company’s PBRSUs based upon expected performance as of March 31, 2017 , and changes during the three 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, 2017 — 390 2 392 $ 57.05 Granted (based on performance at 100% of targeted levels) 132 132 — 264 71.51 Adjustment related to expected performance 66 152 — 218 62.06 Vested — (92 ) — (92 ) 67.30 Forfeited — (26 ) — (26 ) 59.60 Nonvested at March 31, 2017 198 556 2 756 $ 62.21 The total fair value of PBRSUs vested during the three months ended March 31, 2017 and 2016 was $5.1 million and $10.0 million , respectively. As of March 31, 2017 , there was $29.5 million in unrecognized compensation cost related to all nonvested PBRSUs. This cost is expected to be recognized over a weighted-average remaining period of 2.24 years . Employee Stock Purchase Plan The fair value of shares granted under the Company's employee stock purchase plan ("ESPP") was estimated using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended March 31, 2017 2016 Expected volatility 40 % 46 % Expected life 1.51 years 1.68 years Risk-free interest rate 0.63 % 0.58 % Dividend yield — — No shares were purchased under the ESPP during the three months ended March 31, 2017 and 2016 . As of March 31, 2017 , there was $4.4 million in unrecognized compensation cost related to ESPP shares. This cost is expected to be recognized over a weighted-average remaining period of 1.24 years . Modifications Incremental expense associated with modifications to stock options, RSAs and PBRSUs during the three months ended March 31, 2017 and 2016 was $0.1 million and $0.2 million , respectively.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2017
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 three months ended March 31, 2017 are as follows (in thousands): Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Total Balance as of January 1, 2017 $ (4,729 ) $ (547 ) $ (5,276 ) Other comprehensive income 423 69 492 Balance as of March 31, 2017 $ (4,306 ) $ (478 ) $ (4,784 ) For the three months ended March 31, 2017 and 2016 , reclassifications of items from accumulated other comprehensive loss to net income were insignificant.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2017
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. As the Company intends to settle the principal amount of the Notes (see Note 7 , "Debt") in cash upon conversion, their dilutive effect, if any, will be 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. During the three months ended March 31, 2017 and 2016 , the average price of the Company's stock was below the conversion price of the Notes; as a result the Notes were not dilutive for these periods. A reconciliation of the numerator and denominator of basic earnings per share and diluted earnings per share for the three months ended March 31, 2017 and 2016 is shown in the following table (in thousands, except per share data): Three Months Ended March 31, 2017 2016 (1) Numerator Net income $ 9,518 $ 4,575 Denominator Denominator for basic earnings per share: Weighted average common shares outstanding 56,072 55,119 Denominator for diluted earnings per share: Dilutive potential common shares: Stock options 932 970 Restricted stock awards and units 735 348 Performance-based restricted stock units 298 152 Employee stock purchase plan 46 — Weighted average common shares outstanding with assumed conversion 58,083 56,589 Basic earnings per share $ 0.17 $ 0.08 Diluted earnings per share $ 0.16 $ 0.08 (1) Prior period recast to reflect the Company's early adoption of ASU No. 2016-09 in the third quarter of 2016. Anti-dilutive common stock equivalents excluded from the calculation of diluted earnings per share for the three months ended March 31, 2017 and 2016 are shown in the following table (in thousands, except per share data): Three Months Ended March 31, 2017 2016 (1) Stock options 343 623 Restricted stock awards and units 252 181 Performance-based restricted stock units 157 196 Employee stock purchase plan 365 417 Total 1,117 1,417 (1) Prior period recast to reflect the Company's early adoption of ASU No. 2016-09 in the third quarter of 2016.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company's unrecognized tax benefits were approximately $2.9 million as of March 31, 2017 , and were unchanged from December 31, 2016 .

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
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.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENT On April 18, 2017 , the Company acquired Mytrus, Incorporated ("Mytrus") for total cash consideration of approximately $14 million. Mytrus provides cloud-based software for electronic informed consent ("eConsent"), which replaces traditional paper patient consent forms. By adding an eConsent solution to its growing mobile health portfolio, the Company seeks to increase client adoption of its mobile technology while modernizing clinical trials for patients, sites, and sponsors.

Summary of Significant Accoun20

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of presentation	Basis of Presentation — The accompanying interim condensed consolidated balance sheets as of March 31, 2017 and December 31, 2016 , the condensed consolidated statements of operations for the three months ended March 31, 2017 and 2016 , the condensed consolidated statements of comprehensive income for the three months ended March 31, 2017 and 2016 , and the condensed consolidated statements of cash flows for the three months ended March 31, 2017 and 2016 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, 2016 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 28, 2017 . The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all adjustments consisting of normal recurring accruals considered necessary to present fairly the Company’s financial position as of March 31, 2017 , results of its operations for the three months ended March 31, 2017 and 2016 , comprehensive income for the three months ended March 31, 2017 and 2016 , and cash flows for the three months ended March 31, 2017 and 2016 . The results of operations for the three months ended March 31, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 .
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.
Accounts receivable	Accounts Receivable — Accounts receivable are recorded at original invoice amount less an allowance that management believes will be adequate to absorb estimated losses on uncollectible accounts. This allowance is based on an evaluation of the collectability of accounts receivable and prior bad debt experience. Accounts receivable are written off when deemed uncollectible. Unbilled receivables consist of revenue recognized in excess of billings, substantially all of which is expected to be billed and collected within one year. As of March 31, 2017 and December 31, 2016 , unbilled accounts receivable of $14.7 million and $14.1 million , respectively, were included in accounts receivable on the Company's consolidated balance sheets. In general, there is a direct relationship between the Company's accounts receivable balance and its transaction volume.
Recently issued accounting pronouncements	Recently Adopted Accounting Pronouncements — In November 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2015-17, Income Taxes: Balance Sheet Classification of Deferred Taxes , which simplifies the presentation of deferred income taxes by requiring that all deferred tax assets and liabilities be classified as noncurrent in the consolidated balance sheets. ASU No. 2015-17 is effective for annual reporting periods beginning after December 15, 2016 and interim periods within those annual periods, and may be applied either prospectively or retrospectively to all periods presented. The Company adopted ASU No. 2015-17 prospectively on January 1, 2017, and the adoption did not have a material impact on its consolidated financial statements, aside from a balance sheet reclassification from short-term to long-term deferred income taxes. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory, which requires entities to recognize the income tax consequences of intra-entity transfers of assets other than inventory when those transfers occur. ASU No. 2016-16 is effective for annual reporting periods beginning after December 15, 2017, including interim periods within those annual periods. The Company early adopted ASU No. 2016-16 on January 1, 2017, and the adoption had no impact on its consolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows: Restricted Cash , which requires entities to include restricted cash in cash and cash equivalents when reconciling beginning-of-period and end-of-period cash in the statement of cash flows. ASU No. 2016-18 is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. The Company early adopted ASU No. 2016-18 retrospectively on January 1, 2017 and the adoption did not have a material impact on its consolidated financial statements, aside from changes in presentation. Recently Issued Accounting Pronouncements — There have been no changes in the expected dates of adoption or estimated effects on the Company's consolidated financial statements of recently issued accounting pronouncements from those disclosed in the Company’s Annual Report on Form 10-K.
Earnings per share	Basic earnings per share is calculated by dividing net income available to common stockholders by the weighted-average number of shares outstanding during the period. The holders of unvested RSAs do not have nonforfeitable rights to dividends or dividend equivalents and therefore, such vested awards do not qualify as participating securities and are excluded from the basic earnings per share calculation. Diluted earnings per share includes the determinants of basic net income per share and, in addition, gives effect to the potential dilution that would occur if securities or other contracts to issue common stock are exercised, vested, or converted into common stock, unless they are anti-dilutive. As the Company intends to settle the principal amount of the Notes (see Note 7 , "Debt") in cash upon conversion, their dilutive effect, if any, will be 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. During the three months ended March 31, 2017 and 2016 , the average price of the Company's stock was below the conversion price of the Notes; as a result the Notes were not dilutive for these periods.

Investments (Tables)

Investments (Tables)	3 Months Ended
	Mar. 31, 2017
Investments [Abstract]
Marketable securities by security type	The following tables provide the Company’s marketable securities by security type as of March 31, 2017 and December 31, 2016 (in thousands): As of March 31, 2017 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 389,100 $ 2 $ (713 ) $ 388,389 U.S. government agency debt securities 34,636 — (64 ) 34,572 Total $ 423,736 $ 2 $ (777 ) $ 422,961 As of December 31, 2016 Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Commercial paper and corporate bonds $ 389,459 $ 4 $ (827 ) $ 388,636 U.S. government agency debt securities 33,132 — (65 ) 33,067 Total $ 422,591 $ 4 $ (892 ) $ 421,703
Contractual maturities of marketable securities	Contractual maturities of the Company’s marketable securities as of March 31, 2017 and December 31, 2016 are summarized as follows (in thousands): As of March 31, 2017 As of December 31, 2016 Cost Estimated Fair Value Cost Estimated Fair Value Due in one year or less $ 275,007 $ 274,602 $ 281,591 $ 281,285 Due in one to five years 148,729 148,359 141,000 140,418 Total $ 423,736 $ 422,961 $ 422,591 $ 421,703
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 March 31, 2017 and December 31, 2016 (in thousands): In Loss Position for Less than 12 Months As of March 31, 2017 As of December 31, 2016 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 351,361 $ (685 ) $ 299,708 $ (771 ) U.S. government agency debt securities 27,454 (56 ) 28,273 (59 ) Total $ 378,815 $ (741 ) $ 327,981 $ (830 ) In Loss Position for More than 12 Months As of March 31, 2017 As of December 31, 2016 Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Commercial paper and corporate bonds $ 35,021 $ (28 ) $ 68,158 $ (56 ) U.S. government agency debt securities 4,792 (8 ) 4,794 (6 ) Total $ 39,813 $ (36 ) $ 72,952 $ (62 )

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Financial assets and liabilities measured at fair value on a recurring basis	The following table summarizes, as of March 31, 2017 and December 31, 2016 , 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, 2016 (in thousands): As of March 31, 2017 As of December 31, 2016 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Cash $ 90,174 $ — $ — $ 90,174 $ 93,384 $ — $ — $ 93,384 Money market funds 248 — — 248 135 — — 135 Total cash and cash equivalents 90,422 — — 90,422 93,519 — — 93,519 Commercial paper and corporate bonds — 388,389 — 388,389 — 388,636 — 388,636 U.S. government agency debt securities — 34,572 — 34,572 — 33,067 — 33,067 Total marketable securities — 422,961 — 422,961 — 421,703 — 421,703 Total financial assets measured at fair value on a recurring basis $ 90,422 $ 422,961 $ — $ 513,383 $ 93,519 $ 421,703 $ — $ 515,222 Contingent consideration – short-term $ — $ — $ 3,930 $ 3,930 $ — $ — $ — $ — Contingent consideration – long-term — — 1,767 1,767 — — — — Total financial liabilities measured at fair value on a recurring basis $ — $ — $ 5,697 $ 5,697 $ — $ — $ — $ —

Acquisition (Tables)

Acquisition (Tables)	3 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Schedule of finite-lived intangibles acquired as part of a business combination	Intangible assets acquired were as follows (in thousands): Acquisition Date Fair Value Weighted-Average Useful Life Developed technology $ 8,423 5 years Non-competition agreements 60 4 years Total $ 8,483

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of goodwill	The change in the carrying amount of goodwill during the three months ended March 31, 2017 was as follows (in thousands): Balance as of January 1, 2017 $ 30,780 Additions related to acquisition 8,248 Foreign currency translation adjustments 47 Balance as of March 31, 2017 $ 39,075
Intangible assets	Total intangible assets are summarized as follows (in thousands): As of March 31, 2017 As of December 31, 2016 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Carrying Amount Accumulated Amortization Net Carrying Amount Developed technology $ 17,153 $ (5,568 ) $ 11,585 $ 8,714 $ (5,098 ) $ 3,616 Customer relationships 3,570 (2,254 ) 1,316 3,566 (2,176 ) 1,390 Non-competition agreements 210 (75 ) 135 150 (66 ) 84 Total $ 20,933 $ (7,897 ) $ 13,036 $ 12,430 $ (7,340 ) $ 5,090
Annual amortization for the next five years	Future amortization of intangible assets is expected to be as follows (in thousands): Remainder of year ending December 31, 2017 $ 2,447 Years ending December 31, 2018 3,187 2019 2,930 2020 2,198 2021 1,932 2022 342 Total $ 13,036

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Components of convertible senior notes	The Company's 1.00% convertible senior notes (the "Notes"), issued in August 2013, consisted of the following components as of March 31, 2017 and December 31, 2016 (in thousands): March 31, December 31, Equity component, net of equity issue costs $ 60,222 $ 60,222 Liability component: Principal 287,500 287,500 Less: unamortized debt discount (18,797 ) (22,076 ) Less: unamortized debt issuance costs (1,704 ) (2,023 ) Net carrying amount $ 266,999 $ 263,401
Interest expense related to convertible senior notes	The following table sets forth total interest expense recognized related to the Notes for the three months ended March 31, 2017 and 2016 (in thousands except percentages): Three Months Ended March 31, 2017 2016 Contractual interest expense $ 719 $ 719 Amortization of debt issuance costs 319 319 Amortization of debt discount 3,279 3,089 Total $ 4,317 $ 4,127 Effective interest rate 6.5 % 6.5 %

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Components of stock-based compensation expense	For the three months ended March 31, 2017 and 2016 , the components of stock-based compensation expense were as follows (in thousands): Three Months Ended March 31, 2017 2016 Stock options $ 917 $ 1,055 Restricted stock awards and units 6,919 5,478 Performance-based restricted stock units 1,628 2,634 Employee stock purchase plan 928 1,083 Total stock-based compensation (1) $ 10,392 $ 10,250 (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.
Fair value of stock option grants	The fair value of each stock option granted during the three months ended March 31, 2017 and 2016 was estimated on the date of grant using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended March 31, 2017 2016 Expected volatility 44 % 43 % Expected life 6 years 6 years Risk-free interest rate 2.09 % 1.50 % 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 March 31, 2017 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at January 1, 2017 1,793 $23.39 Granted 57 56.74 Exercised (117 ) 22.20 Forfeited (26 ) 45.66 Expired (7 ) 58.92 Outstanding at March 31, 2017 1,700 $24.10 5.06 $57,328 Exercisable at March 31, 2017 1,347 $18.08 4.13 $53,538 Vested and expected to vest at March 31, 2017 1,663 $23.60 4.97 $56,900
Summary of nonvested restricted stock awards	The following table summarizes the status of the Company’s nonvested time-based RSAs and RSUs as of March 31, 2017 , and changes during the three months then ended (in thousands, except per share data): Number of Shares Weighted- Average Grant-Date Fair Value Nonvested at January 1, 2017 1,850 $40.89 Granted 648 56.10 Vested (468 ) 37.82 Forfeited (89 ) 40.97 Nonvested at March 31, 2017 1,941 $46.70
Fair value of TSR PBRSUs	The fair value of PBRSUs with market conditions granted during the three months ended March 31, 2017 and 2016 was estimated as of the date of grant using a Monte Carlo valuation model with the following weighted average assumptions: 2017 TSR PBRSUs 2016 TSR PBRSUs Expected volatility - Medidata 42 % 48 % Expected volatility - comparison index 43 % 43 % Expected life 2.85 years 2.84 years Risk-free interest rate 1.40 % 0.91 % Dividend yield — —
Summary of performance-based restricted stock units based on expected performance	The following table summarizes the status of the Company’s PBRSUs based upon expected performance as of March 31, 2017 , and changes during the three 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, 2017 — 390 2 392 $ 57.05 Granted (based on performance at 100% of targeted levels) 132 132 — 264 71.51 Adjustment related to expected performance 66 152 — 218 62.06 Vested — (92 ) — (92 ) 67.30 Forfeited — (26 ) — (26 ) 59.60 Nonvested at March 31, 2017 198 556 2 756 $ 62.21
Fair value of employee stock purchase plan shares	The fair value of shares granted under the Company's employee stock purchase plan ("ESPP") was estimated using a Black-Scholes pricing model with the following weighted-average assumptions: Three Months Ended March 31, 2017 2016 Expected volatility 40 % 46 % Expected life 1.51 years 1.68 years Risk-free interest rate 0.63 % 0.58 % Dividend yield — —

Accumulated Other Comprehensi27

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2017
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 three months ended March 31, 2017 are as follows (in thousands): Foreign currency translation adjustments Unrealized gains (losses) on marketable securities Total Balance as of January 1, 2017 $ (4,729 ) $ (547 ) $ (5,276 ) Other comprehensive income 423 69 492 Balance as of March 31, 2017 $ (4,306 ) $ (478 ) $ (4,784 )

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Reconciliation of the numerators and denominators of basic and diluted earnings per share	A reconciliation of the numerator and denominator of basic earnings per share and diluted earnings per share for the three months ended March 31, 2017 and 2016 is shown in the following table (in thousands, except per share data): Three Months Ended March 31, 2017 2016 (1) Numerator Net income $ 9,518 $ 4,575 Denominator Denominator for basic earnings per share: Weighted average common shares outstanding 56,072 55,119 Denominator for diluted earnings per share: Dilutive potential common shares: Stock options 932 970 Restricted stock awards and units 735 348 Performance-based restricted stock units 298 152 Employee stock purchase plan 46 — Weighted average common shares outstanding with assumed conversion 58,083 56,589 Basic earnings per share $ 0.17 $ 0.08 Diluted earnings per share $ 0.16 $ 0.08 (1) Prior period recast to reflect the Company's early adoption of ASU No. 2016-09 in the third quarter of 2016.
Schedule of antidilutive securities excluded from computation of earnings per share	Anti-dilutive common stock equivalents excluded from the calculation of diluted earnings per share for the three months ended March 31, 2017 and 2016 are shown in the following table (in thousands, except per share data): Three Months Ended March 31, 2017 2016 (1) Stock options 343 623 Restricted stock awards and units 252 181 Performance-based restricted stock units 157 196 Employee stock purchase plan 365 417 Total 1,117 1,417 (1) Prior period recast to reflect the Company's early adoption of ASU No. 2016-09 in the third quarter of 2016.

Summary of Significant Accoun29

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Unbilled receivables	$ 14.7	$ 14.1

Stockholders' Equity (Details)

Stockholders' Equity (Details) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Equity [Abstract]
Shares paid for tax withholding for share based compensation	242,998	257,878
Shares paid for tax withholding for share based compensation, average price	$ 56.04	$ 33.57
Forfeited restricted stock awards transferred to treasury stock	89,386	54,161
Par value of treasury stock	$ 0.01		$ 0.01

Investments (Details)

Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Marketable securities by security type
Cost	$ 423,736	$ 422,591
Gross unrealized gains	2	4
Gross unrealized losses	(777)	(892)
Estimated fair value	422,961	421,703
Commercial paper and corporate bonds [Member]
Marketable securities by security type
Cost	389,100	389,459
Gross unrealized gains	2	4
Gross unrealized losses	(713)	(827)
Estimated fair value	388,389	388,636
U.S. government agency debt securities [Member]
Marketable securities by security type
Cost	34,636	33,132
Gross unrealized gains	0	0
Gross unrealized losses	(64)	(65)
Estimated fair value	$ 34,572	$ 33,067

Investments (Details 1)

Investments (Details 1) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Marketable securities by contractual maturity
Cost	$ 423,736	$ 422,591
Estimated fair value	422,961	421,703
One year or less [Member]
Marketable securities by contractual maturity
Cost	275,007	281,591
Estimated fair value	274,602	281,285
One to five years [Member]
Marketable securities by contractual maturity
Cost	148,729	141,000
Estimated fair value	$ 148,359	$ 140,418

Investments (Details 2)

Investments (Details 2) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair market value and gross unrealized losses of marketable securities
Less than 12 months in unrealized loss position - fair value	$ 378,815	$ 327,981
Less than 12 months in unrealized loss position - gross unrealized losses	(741)	(830)
12 months or more in unrealized loss position - fair value	39,813	72,952
12 months or more in unrealized loss position - gross unrealized losses	(36)	(62)
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	351,361	299,708
Less than 12 months in unrealized loss position - gross unrealized losses	(685)	(771)
12 months or more in unrealized loss position - fair value	35,021	68,158
12 months or more in unrealized loss position - gross unrealized losses	(28)	(56)
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	27,454	28,273
Less than 12 months in unrealized loss position - gross unrealized losses	(56)	(59)
12 months or more in unrealized loss position - fair value	4,792	4,794
12 months or more in unrealized loss position - gross unrealized losses	$ (8)	$ (6)

Investments (Details Textual)

Investments (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Investments (Textual)
Net realized gains (losses) from the sale of marketable securities	$ 1	$ 0
Cost method investment, description	The Company holds shares of Series B Preferred Stock of SHYFT Analytics, Inc. ("SHYFT"), purchased via a private placement. This investment is accounted for under the cost method and is included in other assets on the Company's consolidated balance sheet
Cost method investment, original cost	$ 4,000

Fair Value (Details)

Fair Value (Details) - Fair value, recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets
Total cash and cash equivalents	$ 90,422	$ 93,519
Total marketable securities	422,961	421,703
Total financial assets	513,383	515,222
Cash [Member]
Assets
Total cash and cash equivalents	90,174	93,384
Money market funds [Member]
Assets
Total cash and cash equivalents	248	135
Commercial paper and corporate bonds [Member]
Assets
Total marketable securities	388,389	388,636
U.S. government agency debt securities [Member]
Assets
Total marketable securities	34,572	33,067
Contingent Consideration [Member]
Liabilities
Contingent consideration - short-term	3,930	0
Contingent consideration - long-term	1,767	0
Total financial liabilities	5,697	0
Level 1 [Member]
Assets
Total cash and cash equivalents	90,422	93,519
Total marketable securities	0	0
Total financial assets	90,422	93,519
Level 1 [Member] | Cash [Member]
Assets
Total cash and cash equivalents	90,174	93,384
Level 1 [Member] | Money market funds [Member]
Assets
Total cash and cash equivalents	248	135
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 1 [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]
Assets
Total cash and cash equivalents	0	0
Total marketable securities	422,961	421,703
Total financial assets	422,961	421,703
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	388,389	388,636
Level 2 [Member] | U.S. government agency debt securities [Member]
Assets
Total marketable securities	34,572	33,067
Level 2 [Member] | Contingent Consideration [Member]
Liabilities
Contingent consideration - short-term	0	0
Contingent consideration - long-term	0	0
Total financial liabilities	0	0
Fair Value, Inputs, Level 3 [Member]
Assets
Total cash and cash equivalents	0	0
Total marketable securities	0	0
Total financial assets	0	0
Fair Value, Inputs, Level 3 [Member] | Cash [Member]
Assets
Total cash and cash equivalents	0	0
Fair Value, Inputs, Level 3 [Member] | Money market funds [Member]
Assets
Total cash and cash equivalents	0	0
Fair Value, Inputs, Level 3 [Member] | Commercial paper and corporate bonds [Member]
Assets
Total marketable securities	0	0
Fair Value, Inputs, Level 3 [Member] | U.S. government agency debt securities [Member]
Assets
Total marketable securities	0	0
Fair Value, Inputs, Level 3 [Member] | Contingent Consideration [Member]
Liabilities
Contingent consideration - short-term	3,930	0
Contingent consideration - long-term	1,767	0
Total financial liabilities	$ 5,697	$ 0

Fair Value (Details Textual)

Fair Value (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Transfers of financial assets between Level 1 and Level 2	$ 0	$ 0
Level 3 fair value inputs and techniques	The fair value of short-term contingent consideration, which is related to the achievement of a technical milestone, has been estimated using situation-based modeling, which considers the probability-weighted present value of the expected payout amount. Significant assumptions include the Company's expectations with regard to the likelihood and timing of achievement of the related technical milestone and a discount rate of 2.9%. The fair value of long-term contingent consideration, which is related to achievement of revenue targets, has been estimated using a Monte Carlo simulation to simulate future performance of the acquired business under a risk-neutral framework; significant assumptions include a risk-adjusted discount rate of 10.2% and revenue volatility of 8.0%.

Acquisition (Details)

Acquisition (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 8,483
Developed technology [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 8,423
Useful life	5 years
Non-competition agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 60
Useful life	4 years

Acquisition (Details Textual)

Acquisition (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Feb. 17, 2017
Business Combinations [Abstract]
Acquisition date	Feb. 17, 2017
Name of acquired entity	CHITA, Inc.
Transaction description	the Company acquired all outstanding equity interests in CHITA Inc. ("CHITA") and its parent company, Daybreak Information Technologies Holdings Limited.
Reason for business combination	CHITA provides regulated content management for the life sciences industry. With this acquisition, the Company adds regulated document and standard operating procedure ("SOP") management to its portfolio of offerings, and expects to add an electronic trial master file ("eTMF") solution built on CHITA's technology in the near future.
Total consideration	$ 14,700
Acquisition date fair value of contingent consideration liability		$ 5,700
Net tangible assets acquired		100
Deferred tax liability recognized		$ 2,100
Goodwill acquired	$ 8,248

Goodwill and Intangible Asset39

Goodwill and Intangible Assets (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Changes in the carrying amount of goodwill
Balance as of beginning of period	$ 30,780
Additions related to acquisition	8,248
Foreign currency translation adjustments	47
Balance as of end of period	$ 39,075

Goodwill and Intangible Asset40

Goodwill and Intangible Assets (Details 1) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Intangible assets
Gross carrying amount	$ 20,933	$ 12,430
Accumulated amortization	(7,897)	(7,340)
Net carrying amount	13,036	5,090
Developed technology [Member]
Intangible assets
Gross carrying amount	17,153	8,714
Accumulated amortization	(5,568)	(5,098)
Net carrying amount	11,585	3,616
Customer relationships [Member]
Intangible assets
Gross carrying amount	3,570	3,566
Accumulated amortization	(2,254)	(2,176)
Net carrying amount	1,316	1,390
Non-competition agreements [Member]
Intangible assets
Gross carrying amount	210	150
Accumulated amortization	(75)	(66)
Net carrying amount	$ 135	$ 84

Goodwill and Intangible Asset41

Goodwill and Intangible Assets (Details 2) $ in Thousands	Mar. 31, 2017USD ($)
Annual amortization for the next five years
Remainder of year current year	$ 2,447
Next twelve months	3,187
Year two	2,930
Year three	2,198
Year four	1,932
Year five	$ 342

Debt (Details)

Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Components of convertible senior notes
Equity component net of equity issue costs	$ 60,222	$ 60,222
Principal amount	287,500	287,500
Unamortized discount	(18,797)	(22,076)
Unamortized debt issuance costs	(1,704)	(2,023)
Convertible senior notes, net carrying amount	$ 266,999	$ 263,401

Debt (Details 1)

Debt (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Interest expense on convertible senior notes
Convertible senior notes, contractual interest expense	$ 719	$ 719
Amortization of debt issuance costs	319	319
Amortization of debt discount	3,279	3,089
Convertible senior notes, total interest expense	$ 4,317	$ 4,127
Convertible senior notes, effective interest rate during period	6.50%	6.50%

Debt (Details Textual)

Debt (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Aug. 12, 2013
Convertible senior notes
Conversion price			$ 58.05
Closing price of the Company's common stock	$ 57.69
Approximate remaining life	16 months
Convertible Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Convertible senior notes
Approximate fair value	$ 326.6	$ 314.4

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Components of stock-based compensation expense
Total stock-based compensation	[1]	$ 10,392	$ 10,250
Stock options [Member]
Components of stock-based compensation expense
Total stock-based compensation		917	1,055
Restricted stock awards and units [Member]
Components of stock-based compensation expense
Total stock-based compensation		6,919	5,478
Performance-based restricted stock units [Member]
Components of stock-based compensation expense
Total stock-based compensation		1,628	2,634
Employee stock purchase plan [Member]
Components of stock-based compensation expense
Total stock-based compensation		$ 928	$ 1,083
[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 (Det46

Stock-Based Compensation (Details 1) - Stock options [Member]	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Weighted-average Black-Scholes assumptions used to estimate fair value of stock options granted
Expected volatility	44.00%	43.00%
Expected term	6 years	6 years
Risk-free interest rate	2.09%	1.50%
Dividend yield	0.00%	0.00%

Stock-Based Compensation (Det47

Stock-Based Compensation (Details 2) - Stock options [Member] $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)$ / sharesshares
Summary of activities and changes in stock option plans
Number of shares outstanding at beginning of period | shares	1,793
Weighted-average exercise price outstanding at beginning of period | $ / shares	$ 23.39
Number of shares granted | shares	57
Weighted-average exercise price granted | $ / shares	$ 56.74
Number of shares exercised | shares	(117)
Weighted-average exercise price exercised | $ / shares	$ 22.20
Number of shares forfeited | shares	(26)
Weighted-average exercise price forfeited | $ / shares	$ 45.66
Number of shares expired | shares	(7)
Weighted-average exercise price expired | $ / shares	$ 58.92
Number of shares outstanding at end of period | shares	1,700
Weighted-average exercise price outstanding at end of period | $ / shares	$ 24.10
Weighted average remaining contractual term outstanding at end of period	5 years 22 days
Aggregate intrinsic value outstanding at end of period | $	$ 57,328
Number of shares exercisable at end of period | shares	1,347
Weighted-average exercise price exercisable at end of period | $ / shares	$ 18.08
Weighted average remaining contractual term exercisable at end of period	4 years 1 month 16 days
Aggregate intrinsic value exercisable at end of period | $	$ 53,538
Number of shares vested and expected to vest at end of period | shares	1,663
Weighted-average exercise price vested and expected to vest at end of period | $ / shares	$ 23.60
Weighted average remaining contractual term vested and expected to vest at end of period	4 years 11 months 19 days
Aggregate intrinsic value vested and expected to vest at end of period | $	$ 56,900

Stock-Based Compensation (Det48

Stock-Based Compensation (Details 3) - Restricted stock awards and units [Member] shares in Thousands	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Summary of time-based nonvested restricted stock awards and units
Nonvested number of shares/units at beggining of period | shares	1,850
Nonvested weighted-average grant-date fair value at beginning of period | $ / shares	$ 40.89
Granted number of shares | shares	648
Granted weighted-average grant-date fair value | $ / shares	$ 56.10
Vested number of shares/units | shares	(468)
Vested weighted-average grant-date fair value | $ / shares	$ 37.82
Forfeited number of shares/units | shares	(89)
Forfeited weighted-average grant-date fair value | $ / shares	$ 40.97
Nonvested number of shares/units at end of period | shares	1,941
Nonvested weighted-average grant-date fair value at end of period | $ / shares	$ 46.70

Stock-Based Compensation (Det49

Stock-Based Compensation (Details 4) - Performance-based restricted stock units [Member] - TSR [Member]	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Assumptions used to estimate fair value of TSR PBRSUs
Expected volatility - Medidata	42.00%	48.00%
Expected volatility - Comparison index	43.00%	43.00%
Expected term	2 years 10 months 5 days	2 years 10 months 4 days
Risk-free interest rate	1.40%	0.91%
Dividend yield	0.00%	0.00%

Stock-Based Compensation (Det50

Stock-Based Compensation (Details 5) - Performance-based restricted stock units [Member] shares in Thousands	3 Months Ended
	Mar. 31, 2017$ / sharesshares
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	392
Nonvested weighted-average grant-date fair value at beginning of period | $ / shares	$ 57.05
Granted number of units (based on performance at 100% of targeted levels)	264
Granted weighted-average grant-date fair value | $ / shares	$ 71.51
Adjustment due to expected performance	218
Adjustment due to expected performance weighted average grant date fair value | $ / shares	$ 62.06
Vested number of shares/units	(92)
Vested weighted-average grant-date fair value | $ / shares	$ 67.30
Forfeited number of shares/units	(26)
Forfeited weighted-average grant-date fair value | $ / shares	$ 59.60
Nonvested number of shares/units at end of period	756
Nonvested weighted-average grant-date fair value at end of period | $ / shares	$ 62.21
Net income [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	0
Granted number of units (based on performance at 100% of targeted levels)	132
Adjustment due to expected performance	(66)
Vested number of shares/units	0
Forfeited number of shares/units	0
Nonvested number of shares/units at end of period	198
TSR [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	390
Granted number of units (based on performance at 100% of targeted levels)	132
Adjustment due to expected performance	152
Vested number of shares/units	(92)
Forfeited number of shares/units	(26)
Nonvested number of shares/units at end of period	556
Sales Goals [Member]
Summary of performance-based restricted stock units based upon expected performance
Nonvested number of shares/units at beggining of period	2
Granted number of units (based on performance at 100% of targeted levels)	0
Adjustment due to expected performance	0
Vested number of shares/units	0
Forfeited number of shares/units	0
Nonvested number of shares/units at end of period	2

Stock-Based Compensation (Det51

Stock-Based Compensation (Details 6) - Employee stock purchase plan [Member]	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Weighted-average Black-Scholes assumptions used to estimate fair value of ESPP shares
Expected volatility	40.00%	46.00%
Expected term	1 year 6 months 2 days	1 year 8 months 4 days
Risk-free interest rate	0.63%	0.58%
Dividend yield	0.00%	0.00%

Stock-Based Compensation (Det52

Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stock based compensation (Textual) [Abstract]
Incremental expense associated with equity modifications	$ 0.1	$ 0.2
Stock options [Member]
Stock based compensation (Textual) [Abstract]
Weighted-average grant-date fair value of stock options granted	$ 25.33	$ 16.94
Total intrinsic value of stock options exercised	$ 4	$ 0.7
Total fair value of shares vested	1.1	0.8
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 6.7
Weighted-average remaining period over which cost is expected to be recognized	2 years 7 months 5 days
Restricted stock awards and units [Member]
Stock based compensation (Textual) [Abstract]
Total fair value of shares vested	$ 26.3	9.4
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 82.1
Weighted-average remaining period over which cost is expected to be recognized	2 years 11 months 7 days
Performance-based restricted stock units [Member]
Stock based compensation (Textual) [Abstract]
Total fair value of shares vested	$ 5.1	$ 10
Unrecognized compensation cost related to non-vested stock-based compensation awards granted	$ 29.5
Weighted-average remaining period over which cost is expected to be recognized	2 years 2 months 26 days
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	132	223
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, 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	market conditions based on the Company's TSR relative to that of the Russell 2000 Index over the three-year period ending December 31, 2018, 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] | Net income [Member]
Stock based compensation (Textual) [Abstract]
Target number of performance-based restricted stock units granted during the period	132
Award terms	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	$ 4.4
Weighted-average remaining period over which cost is expected to be recognized	1 year 2 months 25 days
Shares issued during period under employee stock purchase plan	0	0

Accumulated Other Comprehensi53

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated other comprehensive income
Balance as of beginning of period	$ (5,276)
Other comprehensive income (loss), net of tax	492	$ 1,221
Balance as of end of period	(4,784)
Unrealized gains (losses) on available for sale securities
Accumulated other comprehensive income
Balance as of beginning of period	(547)
Other comprehensive income (loss), net of tax	69
Balance as of end of period	(478)
Foreign currency translation adjustments
Accumulated other comprehensive income
Balance as of beginning of period	(4,729)
Other comprehensive income (loss), net of tax	423
Balance as of end of period	$ (4,306)

Accumulated Other Comprehensi54

Accumulated Other Comprehensive Income (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassifications from accumulated other comprehensive income	$ 2	$ 0

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	[2]
Numerator
Net income	$ 9,518	$ 4,575	[1]
Denominator for basic earnings per share:
Weighted average common shares outstanding	56,072	55,119
Dilutive potential common shares:
Stock options	932	970
Restricted stock awards and units	735	348
Performance-based restricted stock units	298	152
Employee stock purchase plan	46	0
Weighted average common shares outstanding with assumed conversion	58,083	56,589
Basic earnings per share	$ 0.17	$ 0.08
Diluted earnings per share	$ 0.16	$ 0.08
[1]	As a result of the Company's 2016 mid-year early adoption of Accounting Standards Update No. 2016-09, which requires excess tax benefit on equity awards to be presented as an operating activity, the consolidated statement of cash flows for the three months ended March 31, 2016 has been adjusted to reflect an offsetting increase of $1,341 thousand to net cash provided by operating activities and net cash used in financing activities
[2]	Prior period recast to reflect the Company's early adoption of Accounting Standards Update No. 2016-09 in the third quarter of 2016

Earnings Per Share (Details 1)

Earnings Per Share (Details 1) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	[1]
Antidilutive common stock equivalents excluded from the calculation of diluted earnings per share
Antidilutive shares excluded from calculation of diluted earnings (loss) per share	1,117	1,417
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	343	623
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	252	181
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	157	196
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	365	417
[1]	Prior period recast to reflect the Company's early adoption of Accounting Standards Update No. 2016-09 in the third quarter of 2016

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Income Taxes (Textual) [Abstract]
Gross unrecognized tax benefits	$ 2.9	$ 2.9
Changes in tax position	$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details)	3 Months Ended
	Mar. 31, 2017
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.

Subsequent Event (Details)

Subsequent Event (Details)	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent event date	Apr. 18, 2017
Subsequent event description	the Company acquired Mytrus, Incorporated ("Mytrus") for total cash consideration of approximately $14 million. Mytrus provides cloud-based software for electronic informed consent ("eConsent"), which replaces traditional paper patient consent forms. By adding an eConsent solution to its growing mobile health portfolio, the Company seeks to increase client adoption of its mobile technology while modernizing clinical trials for patients, sites, and sponsors.