Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax at the U.S. statutory rate	$ (779,000)	$ (3,347,000)
Change in value of warrant liability	(202,000)	1,505,000
Valuation allowance	981,000	1,841,000
Other	0	1,000
Total	$ 0	$ 0	$ 0