Stock Options and Equity-Classified Warrants (Details) - USD ($)			12 Months Ended
	Dec. 20, 2013	Dec. 10, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Jun. 02, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)							2,095,000
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Vesting period			3 years
Average vesting period			6 years
Weighted-Average Exercise Price Options [Abstract]
Exercised (in dollars per share)	$ 4.66	$ 2.39
Issuance of stock options to certain consultants in exchange for services			$ 61,480
Stock-based compensation expense resulting from stock options and warrants included in the Companys Statements of Operations [Abstract]
Share-based Compensation			$ 7,384,656	$ 6,596,248	$ 3,985,106
Employees [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Estimated annualized forfeiture rate			10.00%	10.00%	12.00%
Stock-based compensation expense resulting from stock options and warrants included in the Companys Statements of Operations [Abstract]
Share-based Compensation			$ 7,158,804	$ 3,316,106	$ 2,900,564
Employees [Member] | Maximum [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Expected lives			10 years
Employees [Member] | Research and development [Member]
Stock-based compensation expense resulting from stock options and warrants included in the Companys Statements of Operations [Abstract]
Share-based Compensation			$ 1,590,267	932,482	241,459
Employees [Member] | General and administrative [Member]
Stock-based compensation expense resulting from stock options and warrants included in the Companys Statements of Operations [Abstract]
Share-based Compensation			5,568,537	2,383,624	2,659,105
Non-employees [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Unrecognized compensation expense related to unvested stock options, granted						$ 0
Weighted-Average Exercise Price Options [Abstract]
Issuance of stock options to certain consultants in exchange for services			0	1,276,000	40,000
Stock-based compensation expense resulting from stock options and warrants included in the Companys Statements of Operations [Abstract]
Share-based Compensation			225,852	1,823,242	898,153
Non-employees [Member] | Research and development [Member]
Stock-based compensation expense resulting from stock options and warrants included in the Companys Statements of Operations [Abstract]
Share-based Compensation			0	86,539	0
Non-employees [Member] | General and administrative [Member]
Stock-based compensation expense resulting from stock options and warrants included in the Companys Statements of Operations [Abstract]
Share-based Compensation			$ 225,852	$ 1,736,703	$ 898,153
Senior Management [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Estimated annualized forfeiture rate			2.00%	2.00%	2.00%
Employees and Directors [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Unrecognized compensation expense related to unvested stock options, granted						$ 5,600,000
Unrecognized compensation cost, recognized as expense over a weighted-average period			1 year 3 months 4 days
Directors [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Estimated annualized forfeiture rate			0.00%	0.00%	0.00%
Stock Options [Member] | Employees [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Share based compensation arrangement by share-based payment award fair value assumptions method used			Black-Scholes option-pricing model
Expected dividend yield			0.00%	0.00%	0.00%
Stock Options [Member] | Employees [Member] | Minimum [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Risk-free interest rate			1.74%	1.74%	0.91%
Expected volatility			74.00%	82.00%	85.00%
Expected lives			6 years	6 years	6 years
Stock Options [Member] | Employees [Member] | Maximum [Member]
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Risk-free interest rate			2.42%	2.12%	2.79%
Expected volatility			85.00%	90.00%	89.00%
Expected lives			10 years	10 years	10 years
Stock Options [Member] | Non-employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)			692,143	167,143	167,143	635,714
Share-based compensation arrangement by share-based payment award, fair value assumptions and methodology [Abstract]
Share based compensation arrangement by share-based payment award fair value assumptions method used				Black-Scholes option-pricing model
Risk-free interest rate			0.00%	2.23%	2.05%
Expected volatility			0.00%	85.00%	84.80%
Expected lives			0 years	10 years	10 years
Expected dividend yield			0.00%	0.00%	0.00%
Number of Options (Employees and Non-Employees) [Abstract]
Outstanding - beginning of year (in shares)			692,143	167,143	142,143
Granted (in shares)			0	550,000	25,000
Exercised (in shares)			0	0	0
Expired/Forfeited (in shares)			(56,429)	(25,000)	0
Outstanding - end of year (in shares)			635,714	692,143	167,143
Exercisable at end of year (in shares)			635,714	692,143	167,143
Weighted average fair value of stock options granted during the year (in dollars per share)			$ 0	$ 2.32	$ 1.98
Weighted-Average Exercise Price Options [Abstract]
Outstanding - beginning of year (in dollars per share)			3.47	5.69	6.20
Granted (in dollars per share)			0	2.76	2.79
Exercised (in dollars per share)			0	0	0
Expired/Forfeited (in dollars per share)			8.54	2.79	0
Outstanding - end of year (in dollars per share)			3.02	3.47	5.69
Exercisable at end of year (in dollars per share)			$ 3.02	$ 3.47	$ 5.69
Stock Options [Member] | Employees and Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)			9,348,592	9,348,592	3,240,850	13,573,862
Number of Options (Employees and Non-Employees) [Abstract]
Outstanding - beginning of year (in shares)			9,348,592	6,228,593	3,240,850
Granted (in shares)			4,590,000	3,180,000	3,323,176
Exercised (in shares)			(287,143)	(1,667)	(476)
Expired/Forfeited (in shares)			0	(24,333)	(127,812)
Expired (in shares)			(77,587)	(34,001)	(207,145)
Outstanding - end of year (in shares)			13,573,862	9,348,592	6,228,593
Exercisable at end of year (in shares)			8,015,164	4,901,511	3,125,720
Weighted average fair value of stock options granted during the year (in dollars per share)			$ 1.88	$ 1.80	$ 1.82
Weighted-Average Exercise Price Options [Abstract]
Outstanding - beginning of year (in dollars per share)			2.83	3.11	4.08
Granted (in dollars per share)			2.61	2.47	2.43
Exercised (in dollars per share)			2.05	1.83	1.93
Expired/Forfeited (in dollars per share)			0	2.81	3.09
Expired (in dollars per share)			5.58	8.18	9.59
Outstanding - end of year (in dollars per share)			3.11	2.83	3.11
Exercisable at end of year (in dollars per share)			$ 3.45	$ 3.22	$ 3.86
Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)			7,349,760	7,349,760	7,518,113	7,225,472
Number of Options (Employees and Non-Employees) [Abstract]
Outstanding - beginning of year (in shares)			7,349,760	8,324,609	7,518,113
Granted (in shares)			0	25,000	816,667
Exercised (in shares)			(10,000)	(340,527)	(8,572)
Expired/Forfeited (in shares)			0	0	0
Expired (in shares)			(114,288)	(659,322)	(1,599)
Outstanding - end of year (in shares)			7,225,472	7,349,760	8,324,609
Exercisable at end of year (in shares)			7,225,472	7,149,760	7,924,609
Weighted average fair value of stock options granted during the year (in dollars per share)			$ 0	$ 3.46	$ 1.31
Weighted-Average Exercise Price Options [Abstract]
Outstanding - beginning of year (in dollars per share)			4.27	4.86	5.09
Granted (in dollars per share)			0	5.60	2.80
Exercised (in dollars per share)			2.50	2.56	4.48
Expired/Forfeited (in dollars per share)			0	0	0
Expired (in dollars per share)			3.82	12.66	14.99
Outstanding - end of year (in dollars per share)			4.28	4.27	4.86
Exercisable at end of year (in dollars per share)			$ 4.28	$ 4.32	$ 4.98
2000 Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)						1,400,000
Share-based compensation, shares subject to stock options (in shares)						600,000
Expiration date			Aug. 06, 2010
Share-based compensation, shares available for future grant (in shares)						0
2008 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)						20,000,000
Share-based compensation, shares subject to stock options (in shares)						13,600,000
Share-based compensation, shares available for future grant (in shares)						6,400,000
Number of Options (Employees and Non-Employees) [Abstract]
Granted (in shares)			100,000
2008 Stock Incentive Plan [Member] | Restricted Stock [Member] | Senior Management [Member]
Weighted-Average Exercise Price Options [Abstract]
Value of restricted shares issued						$ 626,900