Earnings per Common Share - Reconciliation of Numerators and Denominators (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic:
Net (loss) income													$ (15,305)	$ (33,867)	$ 5,285
Less deemed dividend related to beneficial conversion feature on Series B Preferred Stock													0	(12,500)	0
Net (loss) income attributable to common stockholders	$ (696)	$ 354	$ (11,130)	$ (3,833)	$ (7,008)	$ (18,880)	$ (9,770)	$ (10,709)	$ (16,210)	$ (11,951)	$ (14,879)	$ 48,325	$ (15,305)	$ (46,367)	$ 5,285
Weighted average common stock shares outstanding (in shares)													83,213,704	63,165,063	55,355,802
Basic (loss) income per common share (in usd per share)	$ 0	$ 0	$ (0.13)	$ (0.05)	$ (0.13)	$ (0.29)	$ (0.16)	$ (0.18)	$ (0.31)	$ (0.21)	$ (0.27)	$ 0.89	$ (0.18)	$ (0.73)	$ 0.10
Effect of dilutive securities:
Net (loss) income attributable to common stockholders, diluted													$ (15,305)	$ (46,367)	$ 5,285
Weighted average common stock shares outstanding (in shares)													83,213,704	63,165,063	55,355,802
Effect of dilutive options and warrants (in shares)													0	0	1,046,677
Diluted weighted average common shares outstanding (in shares)													83,213,704	63,165,063	56,402,479
Diluted (loss) income per common share (in usd per share)	$ 0	$ 0	$ (0.13)	$ (0.05)	$ (0.13)	$ (0.29)	$ (0.16)	$ (0.18)	$ (0.30)	$ (0.21)	$ (0.27)	$ 0.87	$ (0.18)	$ (0.73)	$ 0.09