Stock Options and Equity-Classified Warrants, Options by Exercise Price Range (Details)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Stock Options [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Number of Options (in shares) | shares	2,865,512
Weighted-Average Remaining Contractual Life	7 years 10 months 10 days
Weighted-Average Exercise Price (in dollars per share)	$ 10.62
Number of Options Exercisable (in shares) | shares	2,074,778
Weighted-Average Contractual Life	7 years 3 months 14 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 13.21
Warrants [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Number of Options (in shares) | shares	3,980,781
Weighted-Average Remaining Contractual Life	8 months 26 days
Weighted-Average Exercise Price (in dollars per share)	$ 4.26
Number of Options Exercisable (in shares) | shares	3,626,613
Weighted-Average Contractual Life	9 months
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 4.23
Range $1.50 - 1.75 [Member] | Stock Options [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	1.50
Range of Exercise Prices, Upper Range (in dollars per share)	$ 1.75
Number of Options (in shares) | shares	829,702
Weighted-Average Remaining Contractual Life	9 years 11 months 16 days
Weighted-Average Exercise Price (in dollars per share)	$ 1.75
Number of Options Exercisable (in shares) | shares	400,000
Weighted-Average Contractual Life	9 years 11 months 16 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 1.75
Range $1.76 - 11.0 [Member] | Stock Options [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	1.76
Range of Exercise Prices, Upper Range (in dollars per share)	$ 11.00
Number of Options (in shares) | shares	720,970
Weighted-Average Remaining Contractual Life	7 years 11 months 23 days
Weighted-Average Exercise Price (in dollars per share)	$ 4.76
Number of Options Exercisable (in shares) | shares	469,910
Weighted-Average Contractual Life	7 years 5 months 19 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 5.92
Range $11.01 - 15.00 [Member] | Stock Options [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	11.01
Range of Exercise Prices, Upper Range (in dollars per share)	$ 15.00
Number of Options (in shares) | shares	776,290
Weighted-Average Remaining Contractual Life	7 years 2 months 12 days
Weighted-Average Exercise Price (in dollars per share)	$ 13.92
Number of Options Exercisable (in shares) | shares	667,290
Weighted-Average Contractual Life	7 years 25 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 13.80
Range $15.01 - 195.30 [Member] | Stock Options [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	15.01
Range of Exercise Prices, Upper Range (in dollars per share)	$ 195.30
Number of Options (in shares) | shares	538,550
Weighted-Average Remaining Contractual Life	5 years 5 months 8 days
Weighted-Average Exercise Price (in dollars per share)	$ 27.36
Number of Options Exercisable (in shares) | shares	537,578
Weighted-Average Contractual Life	5 years 5 months 5 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 27.36
Range $3.00 - 6.00 [Member] | Warrants [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	3.00
Range of Exercise Prices, Upper Range (in dollars per share)	$ 6.00
Number of Options (in shares) | shares	3,252,137
Weighted-Average Remaining Contractual Life	7 months 6 days
Weighted-Average Exercise Price (in dollars per share)	$ 3.19
Number of Options Exercisable (in shares) | shares	2,918,803
Weighted-Average Contractual Life	7 months 13 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 3.08
Range $6.01 - 9.00 [Member] | Warrants [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	6.01
Range of Exercise Prices, Upper Range (in dollars per share)	$ 9.00
Number of Options (in shares) | shares	500,000
Weighted-Average Remaining Contractual Life	1 year 25 days
Weighted-Average Exercise Price (in dollars per share)	$ 6.60
Number of Options Exercisable (in shares) | shares	500,000
Weighted-Average Contractual Life	1 year 25 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 6.60
Range $9.01 - 12.00 [Member] | Warrants [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	9.01
Range of Exercise Prices, Upper Range (in dollars per share)	$ 12.00
Number of Options (in shares) | shares	83,335
Weighted-Average Remaining Contractual Life	3 years 1 month 10 days
Weighted-Average Exercise Price (in dollars per share)	$ 10.44
Number of Options Exercisable (in shares) | shares	62,501
Weighted-Average Contractual Life	3 years 1 month 10 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 10.44
Range $12.01 - 33.60 [Member] | Warrants [Member]
Share based compensation, shares authorized under significant ranges of outstanding stock option plans in period [Abstract]
Range of Exercise Prices, Lower Range (in dollars per share)	12.01
Range of Exercise Prices, Upper Range (in dollars per share)	$ 33.60
Number of Options (in shares) | shares	145,309
Weighted-Average Remaining Contractual Life	1 year 2 months 8 days
Weighted-Average Exercise Price (in dollars per share)	$ 16.65
Number of Options Exercisable (in shares) | shares	145,309
Weighted-Average Contractual Life	1 year 2 months 8 days
Weighted-Average Exercise Price, Options Exercisable (in dollars per share)	$ 16.65