Stockholders' Equity - Stock options and warrants (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) $ / shares $ / warrant shares	Dec. 31, 2017 USD ($) $ / shares $ / warrant shares
Warrants, Number of Shares [Roll Forward]
Warrants, Shares, Beginning of Period	209,818
Warrants Granted	0
Warrants Exercised	0
Warrants Canceled	0
Warrants Expired	(160,164)
Warrants, Shares, End of Period	49,654	209,818
Warrants Weighted Average Exercise Price [Roll Forward]
Weighted Average Exercise Price, Warrants Outstanding, Beginning of Period | $ / warrant	53.20
Weighted Average Exercise Price, Warrants Granted | $ / shares	$ 0.00
Weighted Average Exercise Price, Warrants Exercised | $ / shares	0.00
Weighted Average Exercise Price, Warrants Canceled | $ / shares	0.00
Weighted Average Exercise Price, Warrants Expired | $ / shares	$ 50.30
Weighted Average Exercise Price, Warrants Outstanding, End of Period | $ / warrant	62.70	53.20
Weighted Average Remaining Contractual Term, Warrant outstanding	2 years 8 months 12 days	11 months 12 days
Aggregate Intrinsic Value, Warrants Outstanding | $	$ 300	$ 0
Warrants, vested and expected to vest	49,654
Weighted Average Exercise Price, Warrants vested & expected to vest | $ / warrant	62.70
Weighted Average Remaining Contractual Term, Warrants Vested and Expect to Vest	2 years 8 months 12 days
Aggregate Intrinsic Value, Warrants vested and expected to vest | $	$ 300
Warrants, Vested. Number	49,654
Warrants, Vested, Weighted Average Exercise Price | $ / warrant	62.70
Warrants, Vested, Weighted Average Remaining Contractual Term	2 years 8 months 12 days
Warrants, Vested, Aggregate Intrinsic Value | $	$ 300
US Equity Plan [Member]
Options, Outstanding [Roll Forward]
Options, Outstanding, Beginning of Period	1,072,499
Options, Grants in Period, Net of Forfeitures	156,760
Options, Exercises in Period	(77,498)
Options, Forfeitures in Period	(3,030)
Options, Expirations in Period	(112,460)
Options, Outstanding, End of Period	1,036,271	1,072,499
Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options, Outstanding, Weighted Average Exercise Price, Beginning of Period | $ / shares	$ 33.50
Options, Grants in Period, Weighted Average Exercise Price | $ / shares	4.00
Options, Exercises in Period, Weighted Average Exercise Price | $ / shares	4.60
Options, Forfeitures in Period, Weighted Average Exercise Price | $ / shares	3.80
Options, Expirations in Period, Weighted Average Exercise Price | $ / shares	33.20
Options, Outstanding, Weighted Average Exercise Price, End of Period | $ / shares	$ 30.50	$ 33.50
Options, Outstanding, Weighted Average Remaining Contractual Term	5 years 5 months 16 days	4 years 9 months 4 days
Options, Outstanding, Intrinsic Value | $	$ 903,200	$ 100
Options, Vested and Expected to Vest, Outstanding, Number	1,021,775
Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price | $ / shares	$ 30.90
Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	5 years 4 months 28 days
Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value | $	$ 876,400
Options, Vested and Expected to Vest, Exercisable, Number	914,102
Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price | $ / shares	$ 34.00
Options, Vested, Weighted Average Remaining Contractual Term	4 years 11 months 9 days
Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value | $	$ 678,800