Warrants - Activity (Details) - $ / shares	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Shares
Outstanding at beginning of period (in shares)	979,869
Exercised (in shares)	(75,399)
Expired (in shares)	0
Outstanding at end of period (in shares)	904,470
Exercisable at end of period (in shares)	904,470
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 6.36
Exercised (in dollars per shares)	19.46
Expired ( in dollars per share)	0.00
Outstanding at end of period (in dollars per share)	5.27
Exercisable at end of period (in dollars per share)	5.27
Range of Exercise Prices
Expired (in dollars per share)	$ 0.00
Temporary equity, shares outstanding (in shares)	21,920	21,920
Minimum
Range of Exercise Prices
Outstanding at beginning of period (in dollars per share)	$ 2.20
Outstanding at end of period (in dollars per share)	2.20
Exercisable (in dollars per share)	2.20
Maximum
Range of Exercise Prices
Outstanding at beginning of period (in dollars per share)	21.00
Outstanding at end of period (in dollars per share)	21.00
Exercisable (in dollars per share)	$ 21.00