Warrants - Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Warrants
Warrants outstanding beginning balance	123,037	2,099,199	337,746
Warrants issued	58,334	15,750	1,890,602
Warrants exercised	(111,715)	(101,310)	(129,149)
Warrants expired		(1,890,602)
Warrants outstanding ending balance	69,656	123,037	2,099,199
Weighted average exercise price
Beginning balance (in dollars per share)	$ 6.35	$ 5.21	$ 3.06
Issued (in dollars per share)	8.10	3.06	5.33
Exercised (in dollars per share)	6.73	1.30	1.30
Expired (in dollars per share)		5.33
Ending balance (in dollars per share)	$ 7.21	$ 6.35	$ 5.21