Commitments and Contingencies - Summary of Liability Related to Lease (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Commitments and Contingencies Disclosure [Abstract]
Beginning balance	$ 3,033	$ 1,787
Net rental payments	(461)	(256)
Accretion of discount	117	79
Increase in net estimated contract termination costs	206	741
Ending balance	$ 2,895	$ 2,351