Warrants - Warrant Activity (Details)	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Increase (Decrease) in Warrants Outstanding [Roll Forward]
Beginning balance, number of warrants outstanding (shares)	7,392,966
Granted (shares)	0
Exercised (shares)	0
Expired (shares)	0
Ending balance, number of warrants outstanding (shares)	7,392,966
Beginning balance, weighted-average exercise price (usd per share) | $ / shares	$ 7.36
Weighted-average exercise price, warrants granted during the period (usd per share) | $ / shares	0.00
Weighted-average exercise price, warrants exercised during the period (usd per share) | $ / shares	0.00
Weighted-average exercise price, warrants expired during the period (usd per share) | $ / shares	0.00
Ending balance, weighted-average exercise price (usd per share) | $ / shares	$ 7.36
Warrant
Increase (Decrease) in Warrants Outstanding [Roll Forward]
Beginning balance, number of warrants outstanding (shares)	1,205,840
Granted (shares)	0
Exercised (shares)	0
Expired (shares)	0
Ending balance, number of warrants outstanding (shares)	1,205,840
Warrant
Increase (Decrease) in Warrants Outstanding [Roll Forward]
Beginning balance, number of warrants outstanding (shares)	6,187,126
Granted (shares)	0
Exercised (shares)	0
Expired (shares)	0
Ending balance, number of warrants outstanding (shares)	6,187,126