Computation of Basic and Diluted Earnings per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net loss, basic	$ (630,210)	$ (171,799)	$ (133,969)
Gain on common stock held by the NQDC	(3,184)
Net loss, diluted	$ (633,394)	$ (171,799)	$ (133,969)
Weighted-average common shares outstanding, basic	165,985	160,025	146,349
Common shares held by the NQDC	234	0	0
Weighted-average common shares outstanding, diluted	166,219	160,025	146,349
Net loss per common share, basic	$ (3.80)	$ (1.07)	$ (0.92)
Net loss per common share, diluted	$ (3.81)	$ (1.07)	$ (0.92)