Stockholders’ Equity - Common Stock Warrant Activity (Details) - $ / shares	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Class of Warrant or Right
Outstanding warrants, beginning of period	5,469,673
Outstanding warrants, end of period	2,768,882
Warrant exercise price per share	$ 0.08	$ 1.90
Expiration Date - November 2017
Class of Warrant or Right
Exercised (1)	(2,700,791)
Warrant exercise price per share	$ 3.76