Stockholders' Equity and Dilutive Equity Instruments - Additional Information (Detail) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Stockholders Equity Note [Line Items]
Shares issuable upon exercise of warrants	0	108,044
Common stock, shares outstanding	37,381,954	23,988,075	36,978,280
Warrants outstanding	4,117,258	6,021,696
Common shares and new creditor warrants outstanding	41,499,212	30,009,771
In-the-money Warrants and Restricted Stock Awards and Units
Stockholders Equity Note [Line Items]
Incremental "in-the-money" warrants, and restricted stock awards and units	4,327,358	6,255,686
Out-of-the-money Warrants
Stockholders Equity Note [Line Items]
Warrants outstanding	5,923,399	5,062,089