Stockholders' Equity - Stock Options and Warrants (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) $ / shares $ / warrant shares	Dec. 31, 2018 USD ($) $ / shares $ / warrant shares
Warrants, Number of Shares [Roll Forward]
Warrants, Outstanding, Beginning of Period (in shares)	30,000
Warrants, Granted (in shares)	0
Warrants, Exercised (in shares)	0
Warrants, Forfeited (in shares)	0
Warrants, Expired (in shares)	0
Warrants, Outstanding, End of Period (in shares)	30,000	30,000
Warrants Weighted Average Exercise Price [Roll Forward]
Warrants Outstanding, Beginning of Period (in dollars per share) | $ / warrant	5.89
Warrants, Granted (in dollars per share) | $ / shares	$ 0.00
Warrants, Exercised (in dollars per share) | $ / shares	0.00
Warrants, Forfeited (in dollars per share) | $ / shares	0.00
Warrants, Expired (in dollars per share) | $ / shares	$ 0.00
Warrants Outstanding, End of Period (in dollars per share) | $ / warrant	5.89	5.89
Warrants, Outstanding, Weighted Average Remaining Contractual Term	3 years 5 months 12 days	4 years 2 months 9 days
Warrants Outstanding, Aggregate Intrinsic Value | $	$ 0	$ 0
Warrants, Vested and expected to vest (in shares)	30,000
Warrants, Vested and expected to vest, Weighted Average Exercise Price (in dollars per share) | $ / warrant	5.89
Warrants, Vested and expected to vest, Weighted Average Remaining Contractual Term	3 years 5 months 12 days
Warrants, Vested and expected to vest, Aggregate Intrinsic Value | $	$ 0
Warrants, Vested (in shares)	30,000
Warrants, Vested, Weighted Average Exercise Price (in dollars per share) | $ / warrant	5.89
Warrants, Vested, Weighted Average Remaining Contractual Term	3 years 5 months 12 days
Warrants, Vested, Aggregate Intrinsic Value | $	$ 0
US Equity Plan [Member]
Options, Outstanding [Roll Forward]
Options, Outstanding, Beginning of Period (in shares)	1,018,530
Options, Granted (in shares)	209,346
Options, Exercised (in shares)	(240)
Options, Forfeited (in shares)	(2,610)
Options, Expired (in shares)	(130,354)
Options, Outstanding, End of Period (in shares)	1,094,672	1,018,530
Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options, Outstanding. Beginning of Period (in dollars per share) | $ / shares	$ 30.54
Options, Granted (in dollars per share) | $ / shares	4.86
Options, Exercised (in dollars per share) | $ / shares	3.54
Options, Forfeited (in dollars per share) | $ / shares	4.63
Options, Expired (in dollars per share) | $ / shares	57.67
Options, Outstanding, End of Period (in dollars per share) | $ / shares	$ 22.47	$ 30.54
Options, Outstanding, Weighted Average Remaining Contractual Term	6 years 11 days	5 years 3 months 18 days
Options, Outstanding, Aggregate Intrinsic Value | $	$ 0	$ 3,300
Options, Vested and expected to vest (in shares)	1,074,281
Options, Vested and expected to vest, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 22.81
Options, Vested and expected to vest, Weighted Average Remaining Contractual Term	5 years 11 months 19 days
Options, Vested and expected to vest, Aggregate Intrinsic Value | $	$ 0
Options, Vested (in shares)	854,347
Options, Vested, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 27.50
Options, Vested, Weighted Average Remaining Contractual Term	5 years 2 months 12 days
Options, Vested, Aggregate Intrinsic Value | $	$ 0