Commitments and Contingencies - Summary of Liability Related to Lease (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]
Beginning balance	$ 3,033	$ 1,787
Net rental payments	(903)	(281)
Accretion of discount	173	125
Increase in net estimated contract termination costs	206	1,018
Ending balance	$ 2,509	$ 2,649