Cash and Cash Equivalents, Restricted Cash and Short-Term Investments - Summary of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Cash and Cash Equivalents [Abstract]
Cash	$ 1,851	$ 1,511
Money market	69,261	33,255
Total cash and cash equivalents	71,112	34,766	$ 52,566	$ 10,014
Total restricted cash	0	250
Total	$ 71,112	$ 35,016