Securities that Potentially Dilute Calculation of Diluted Earnings Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Warrants to purchase common stock	14,151,732	827,769
Warrants to purchase common stock - liability classified
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Warrants to purchase common stock	14,017,373	698,056
Warrant to purchase common stock - equity classified
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Warrants to purchase common stock	1,393	4,200
2017 Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Warrants to purchase common stock	47,827	75,192
2022 Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Warrants to purchase common stock	688	13,117
Outstanding options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Warrants to purchase common stock	76,915	23,756
Unvested restricted common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Warrants to purchase common stock	7,536	13,448