Earnings per Common Share - Reconciliation of Numerators and Denominators of Basic and Diluted Loss Per Share Computations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Basic:
Net income (loss)	$ (11,951)	$ (15,977)	$ 21,495	$ (51,196)
Weighted average common shares outstanding	55,604,708	53,767,099	55,170,569	53,531,770
Basic income (loss) per common share	$ (0.21)	$ (0.30)	$ 0.39	$ (0.96)
Effect of dilutive securities:
Net income (loss)	$ (11,951)	$ (15,977)	$ 21,495	$ (51,196)
Weighted average common shares outstanding	55,604,708	53,767,099	55,170,569	53,531,770
Effect of dilutive options and warrants			1,033,789
Diluted weighted average common shares outstanding	55,604,708	53,767,099	56,204,358	53,531,770
Diluted income (loss) per common share	$ (0.21)	$ (0.30)	$ 0.38	$ (0.96)