Stockholders' Equity - Stock Option Activity (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2017
Equity [Abstract]
Unrecognized compensation cost, net of forfeitures	$ 2,600,000			$ 2,600,000
Weighted average period to recognize stock compensation expense				1 year 6 months
Options
Outstanding, Beginning Balance	6,665,541	6,860,968	6,447,594	6,447,594
Granted during period	0	198,350	653,842
Exercised during period	0	(44,501)	(7,757)
Expired during period	(336,625)	(123,874)	(163,836)
Forfeited during period	(63,583)	(225,402)	(68,875)
Outstanding, Ending Balance	6,265,333	6,665,541	6,860,968	6,265,333
Weighted-Average Exercise Price
Outstanding, Beginning Balance	$ 5.89	$ 5.96	$ 6.41	$ 6.41
Granted during period	0.00	2.27	2.17
Exercised during period	0.00	2.10	2.10
Expired during period	7.08	8.41	8.82
Forfeited during period	4.71	4.15	5.59
Outstanding, Ending Balance	$ 5.84	$ 5.89	$ 5.96	$ 5.84
Additional disclosures
Options, Exercisable	4,770,246	5,083,084	5,085,833	4,770,246
Weighted Average Exercise Price, Exercisable	$ 6.59	$ 6.63	$ 6.72	$ 6.59
Weighted Average Remaining Contractual Term	5 years 9 months 29 days	6 years 1 month 2 days	6 years 3 months 7 days
Weighted Average Remaining Contractual Term exercisable at end of period	4 years 11 months 9 days	5 years 2 months 19 days	5 years 3 months 29 days
Aggregate Intrinsic Value	$ 0		$ 282,786	$ 0
Aggregate Intrinsic Value, exercisable at end of period	$ 0		$ 29,895	$ 0