Earnings per Common Share - Reconciliation of Numerators and Denominators (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	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, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic:
Net income (loss)													$ 25,711	$ (15,305)	$ (33,867)
Less deemed dividend related to beneficial conversion feature on Series B Preferred Stock													0	0	(12,500)
Net income (loss) attributable to common stockholders	$ 10,197	$ 9,383	$ 1,165	$ 4,966	$ (696)	$ 354	$ (11,130)	$ (3,833)	$ (7,008)	$ (18,880)	$ (9,770)	$ (10,709)	$ 25,711	$ (15,305)	$ (46,367)
Weighted average common shares outstanding (in shares)													99,830,520	83,213,704	63,165,063
Basic income (loss) per common share (in usd per share)	$ 0.10	$ 0.09	$ 0.01	$ 0.05	$ 0	$ 0	$ (0.13)	$ (0.05)	$ (0.13)	$ (0.29)	$ (0.16)	$ (0.18)	$ 0.26	$ (0.18)	$ (0.73)
Effect of dilutive securities:
Net income (loss) attributable to common stockholders, diluted													$ 25,711	$ (15,305)	$ (46,367)
Weighted average common stock shares outstanding (in shares)													99,830,520	83,213,704	63,165,063
Effect of dilutive options and warrants (in shares)													5,232,002	0	0
Diluted weighted average common shares outstanding (in shares)													105,062,522	83,213,704	63,165,063
Diluted income (loss) per common share (in usd per share)	$ 0.10	$ 0.09	$ 0.01	$ 0.05	$ 0	$ 0	$ (0.13)	$ (0.05)	$ (0.13)	$ (0.29)	$ (0.16)	$ (0.18)	$ 0.24	$ (0.18)	$ (0.73)