Fair Value - Summary of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Assets measured at fair value
Cash and cash equivalents	$ 71,112	$ 34,766	$ 52,566	$ 10,014
Restricted cash	0	250
Total Assets measured at fair value	71,112	35,016
Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value
Cash and cash equivalents	71,112	34,766
Restricted cash		250
Total Assets measured at fair value	$ 71,112	$ 35,016