Going Concern - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents, at Carrying Value	$ 5,160,070		$ 7,585,392
Net Income (Loss) Attributable to Parent	(5,811,634)	$ 22,039,472
Gain (Loss) on Derivative Instruments, Net, Pretax	(3,159,532)	25,614,305
Operating Expenses	2,675,867	3,574,833
Net Cash Provided by (Used in) Operating Activities	(2,440,218)	(3,604,025)
Retained Earnings (Accumulated Deficit)	(176,814,142)		(171,002,508)
Stockholders' deficit	(467,983)	(8,856,812)	$ 5,236,096	$ (34,176,885)
Stock Issued During Period, Value, Stock Options Exercised		$ 400,759
Cash requirements for fixed, on-going expenses such as payroll, legal and accounting, patents and overhead at an average cash burn rate	700,000
Warrant to purchase shares of common stock [Member]
Stock Issued During Period, Value, Stock Options Exercised	$ 20,000