Accounts Payable & Other Current Liabilities - Summary of Accounts Payable and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Accounts payable	$ 2,072	$ 2,068
Accrued expenses and other liabilities:
Employee benefits and compensation related accruals	1,431	2,257
General and administrative related accruals	1,289	731
Research and development related accruals	4,263	3,280
Accrued income taxes	8,655	0
Accounts payable and other accrued liabilities	$ 17,710	$ 8,336