Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Customer	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Summary Of Significant Accounting Policy [Line Items]
Original maturities	90 days
Number of customers accounted for revenues or accounts receivable greater than 2% of total | Customer	0
Annual goodwill impairment test, period	November 30
Goodwill impairment charges	$ 0	$ 0	$ 0
Non-current deferred rent liabilities	6,436,000	6,501,000
Foreign exchange losses		100,000	$ 400,000
Unamortized fair value stock based compensation	$ 16,200,000
Weighted average remaining recognition period	2 years 6 months
Research Service Revenue [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policy [Line Items]
Customer accounted for percentage	2.00%
Accounts Receivable [Member] | Credit Concentration Risk [Member]
Summary Of Significant Accounting Policy [Line Items]
Customer accounted for percentage	2.00%
Pre -Tax Expenses [Member]
Summary Of Significant Accounting Policy [Line Items]
Out-of-Period correction value		300,000
Post-Tax Expenses [Member]
Summary Of Significant Accounting Policy [Line Items]
Out-of-Period correction value		200,000
Depreciation Expenses [Member]
Summary Of Significant Accounting Policy [Line Items]
Out-of-Period correction value		400,000
Other Immaterial Expenses [Member]
Summary Of Significant Accounting Policy [Line Items]
Out-of-Period correction value		(100,000)
Additional Income Tax Expense [Member]
Summary Of Significant Accounting Policy [Line Items]
Out-of-Period correction value		$ 500,000