Earnings per Common Share - Reconciliation of Numerators and Denominators of Basic and Diluted Earnings Per Common Share Computations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic:
Net (loss) income	$ (6,380)	$ (11,951)	$ (26,859)	$ 21,495
Less deemed dividend related to beneficial conversion feature on Series B Preferred Stock	(12,500)		(12,500)
Net (loss) income attributable to common stockholders, basic	$ (18,880)	$ (11,951)	$ (39,359)	$ 21,495
Weighted average common shares outstanding	64,900,007	55,604,708	60,599,456	55,170,569
Basic (loss) income per common share	$ (0.29)	$ (0.21)	$ (0.65)	$ 0.39
Effect of dilutive securities:
Net (loss) income attributable to common stockholders, diluted	$ (18,880)	$ (11,951)	$ (39,359)	$ 21,495
Weighted average common shares outstanding	64,900,007	55,604,708	60,599,456	55,170,569
Effect of dilutive options and warrants				1,033,789
Diluted weighted average common shares outstanding	64,900,007	55,604,708	60,599,456	56,204,358
Diluted (loss) income per common share	$ (0.29)	$ (0.21)	$ (0.65)	$ 0.38