Commitments and Contingencies - Summary of Liability Related to Lease (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Beginning balance	$ 2,106	$ 3,033
Net rental payments	(691)	(1,352)
Accretion of discount	145	220
(Decrease) increase in net estimated contract termination costs	(85)	205
Ending balance	$ 1,475	$ 2,106