Summary of Significant Accounting Policies - Additional Information (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Customer shares	Dec. 31, 2017 USD ($) Customer shares	Dec. 31, 2016 USD ($) shares	Jan. 01, 2018 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Sales rebates		$ 200,000
Sales rebates on revenue	$ 1,200,000
Performance obligations remaining to be performed	$ 1,060,700,000
Number of customers accounted for more than 10% of accounts receivable | Customer	0	0
Disbursement of pre-funded study costs		$ 138,700,000	$ 150,300,000
Fair value measurements transfers between level 1, level 2, or level 3	$ 0	0	$ 0
Accumulated deficit	(41,487,000)	(120,402,000)
Accounts receivable and unbilled, net	133,449,000	83,079,000
Deferred income tax liability	439,000	560,000
Accrued expenses	87,493,000	23,673,000
Pre-funded study costs	0	57,406,000
Advanced billings	147,935,000	$ 73,756,000
ASC 606
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable and unbilled, net				$ 106,966,000
Pre-funded study costs				0
Advanced billings				112,613,000
ASC 606 | Impact of Adoption of ASC 606 - Adjustments
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	2,637,000			5,700,000
Accounts receivable and unbilled, net	(28,729,000)			23,887,000
Deferred income tax liability	2,049,000			(1,600,000)
Accrued expenses	(51,109,000)			35,100,000
Pre-funded study costs	61,156,000			(57,406,000)
Advanced billings	$ (41,732,000)			$ 38,857,000
Stock Options
Summary Of Significant Accounting Policies [Line Items]
Anti-dilutive securities excluded from computation of diluted EPS | shares	121	63	0
Maximum
Summary Of Significant Accounting Policies [Line Items]
Sales rebates			$ 100,000
Estimated useful life of intangible assets	15 years
Maximum | Accounting Standard Update (“ASU”) No. 2016-09
Summary Of Significant Accounting Policies [Line Items]
Discrete Adjustments to Income Tax Expense Benefit		$ 100,000
Maximum | Computer Hardware Software Phone and Medical Imaging Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets	5 years
Maximum | Furniture and Fixtures and Other Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets	7 years
Maximum | Buildings
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets	40 years
Maximum | Computer Software Developed Costs
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets	3 years
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets	5 years
Minimum | Computer Hardware Software Phone and Medical Imaging Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets	3 years
Minimum | Furniture and Fixtures and Other Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets	5 years
Minimum | Buildings
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets	30 years
Miscellaneous Income (Expense), Net
Summary Of Significant Accounting Policies [Line Items]
Net gain (loss) on foreign currency transactions	$ 400,000	(1,000,000.0)	(700,000)
Selling, General and Administrative
Summary Of Significant Accounting Policies [Line Items]
Advertisement expenses	$ 800,000	$ 600,000	$ 600,000