Warrants - Warrants Activity (Detail) - $ / shares shares in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Number of Warrants Outstanding
Number of Warrants Outstanding, Ending Balance	6,866
Warrants [Member]
Number of Warrants Outstanding
Number of Warrants Outstanding, Beginning Balance	7,116
Number of Warrants, Warrants exercised	(250)
Number of Warrants Outstanding, Ending Balance	6,866	7,116
Warrants, Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding Beginning Balance	$ 0.57
Weighted Average Exercise Price, Warrants exercised	0.40
Weighted Average Exercise Price, Outstanding Ending Balance	$ 0.57	$ 0.57
Weighted Average Remaining Contractual Life
Weighted Average Remaining Contractual Life, Warrants Outstanding	2 years 10 months 24 days	3 years 4 months 28 days
Equity based-warrants
Number of Warrants Outstanding
Number of Warrants Outstanding, Ending Balance	2,700
Liability warrants
Number of Warrants Outstanding
Number of Warrants Outstanding, Ending Balance	4,200