Commitments and Contingencies - Additional Information (Detail) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($) Employees	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)
Operating Leased Assets [Line Items]
Total rent expense	$ 1.9		$ 1.5	$ 3.4	$ 3.0
Life Sciences Tax Incentive Program 2015 [Member]
Operating Leased Assets [Line Items]
Tax incentive awarded		$ 1.4
State research and development tax credits monetized		$ 1.2
Number of incremental employees pledged to be hired | Employees		75
Performance period		5 years