Cash and Cash Equivalents, Restricted Cash and Short-Term Investments - Summary of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Cash and Cash Equivalents [Abstract]
Cash	$ 874
Money market	52,019
Total cash and cash equivalents	52,893	$ 34,766	$ 44,344	$ 10,014
Total restricted cash	0	250
Total	$ 52,893	$ 35,016