Net Loss Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net loss	$ (33,273)	$ (28,870)	$ (97,573)	$ (73,734)
Less: Participation rights of the Forward Transactions	0	0	0	0
Net loss attributable to common stock	$ (33,273)	$ (28,870)	$ (97,573)	$ (73,734)
Weighted-average common shares outstanding-basic and diluted	79,003	78,633	78,864	80,047
Net loss attributable to common stock per share-basic and diluted	$ (0.42)	$ (0.37)	$ (1.24)	$ (0.92)