Warrants - Summary of Change in Warrant (Detail) - Warrants Not Settleable in Cash - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Class of Warrant or Right [Line Items]
Number of Warrants, Outstanding, Beginning balance (in shares)	2,071,172
Number of Warrants, Sold or Granted (in shares)	50,735,292
Number of Warrants, Exercised (in shares)	0
Number of Warrants, Expired (in shares)	(2,040,757)
Number of Warrants, Adjustment to number of warrant shares due to down-round adjustment (in shares)	607,687
Number of Warrants, Outstanding, Ending balance (in shares)	51,373,394	2,071,172
Weighted Average Exercise Price, Outstanding (in dollars per share), Beginning balance	$ 2.05
Weighted Average Exercise Price, Sold or Granted (in dollars per share)	0.68
Weighted Average Exercise Price, Exercised (in dollars per share)	0
Weighted Average Expercise Price, Expired (in dollars per share)	1.24
Weighted Average Exercise Price, Adjustment to number of warrant shares due to down-round adjustment (in dollars per share)	0.37
Weighted Average Exercise Price, Outstanding (in dollars per share), Ending balance	$ 0.71	$ 2.05
Weighted Average Remaining Contractual Life, Outstanding	2 years 10 months 24 days	2 years 4 months 24 days
Weighted Average Remaining Contractual Life, Sold or Granted	2 years 10 months 24 days
Weighted Average Remaining Contractual Life, Adjustment to number of warrant shares due to down-round adjustment	2 years 1 month 6 days
Weighted Average Fair Value, Outstanding (in dollars per share)	$ 0.13	$ 1.34
Weighted Average Fair Value, Sold or Granted (in dollars per share)	0.12
Weighted Average Fair Value, Adjustment to number of warrant shares due to down-round adjustment	$ 0.14