401(K) Savings Plan - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution expenses	$ 0.3	$ 0.2
First 3% of each Participant's Contributions
Defined Benefit Plan Disclosure [Line Items]
Company's matching contributions to the 401(k)plan	100.00%
Second 2% of each Participant's Contributions
Defined Benefit Plan Disclosure [Line Items]
Company's matching contributions to the 401(k)plan	50.00%