Income (loss) per Common Share - Computation of Basic and Diluted Net Income (loss) Per Common Share (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, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net loss	$ (27,714)	$ (30,794)	$ 6,631	$ (11,540)	$ (13,045)	$ (26,084)	$ (27,506)	$ (5,591)	$ (63,417)	$ (72,226)	$ (29,217)
Adjustments for basic net loss per common share:
Dividend accrued on redeemable preferred stock									(30,729)	(26,840)	(23,443)
Dividend requirements									(300)	(300)	(300)
Net loss attributable to common stockholders	$ (36,411)	$ (39,133)	$ (1,530)	$ (19,367)	$ (20,705)	$ (33,422)	$ (35,011)	$ (13,603)	$ (96,441)	$ (102,741)	$ (59,447)
Denominator:
Denominator for basic and dilutive net loss per common share - adjusted weighted-average shares									28,039,625	27,490,717	27,250,876
Basic and dilutive income (loss) per common share:
Loss from continuing operations									$ (3.44)	$ (3.74)	$ (2.22)
Income from discontinued operations, net of taxes											0.04
Net loss	$ (1.30)	$ (1.39)	$ (0.05)	$ (0.69)	$ (0.75)	$ (1.22)	$ (1.27)	$ (0.49)	$ (3.44)	$ (3.74)	$ (2.18)
Series E Redeemable Preferred Stock [Member]
Adjustments for basic net loss per common share:
Dividend accrued on redeemable preferred stock									$ (30,729)	$ (26,840)	$ (23,443)
Accretion of redeemable preferred stock									(1,995)	(3,375)	(6,487)
Series B Preferred Stock [Member]
Adjustments for basic net loss per common share:
Dividend requirements									(240)	(240)	(240)
Series D Preferred Stock [Member]
Adjustments for basic net loss per common share:
Dividend requirements									$ (60)	$ (60)	$ (60)