Summary of Significant Accounting Policies (Details 4) (USD $)	3 Months Ended								12 Months Ended			1 Months Ended	12 Months Ended	1 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 31, 2011	Dec. 31, 2011	Feb. 28, 2013	Jan. 31, 2014	Jan. 15, 2014
Stock-Based Compensation
Tax benefit (expense) for stock-based compensation									$ 0	$ 0	$ 0
Numerator
Net loss attributable to common shareholders	$ (7,183,000)	$ (9,377,000)	$ 3,825,000	$ (75,909,000)	$ (28,929,000)	$ (15,948,000)	$ (9,338,000)	$ (8,576,000)	$ (88,643,700)	$ (62,790,800)	$ (31,862,454)
Denominator
Weighted Average Number of Shares Outstanding, Basic and Diluted									159,228,815	76,436,408	34,376,427
Number of dilutive potential common shares									18,614,643	40,464,065	11,407,263
Common stock warrants	4,219,442								4,219,442
Weighted average exercise price of warrants (in dollars per share)	$ 3.84								$ 3.84							$ 4.00
Stock options
Denominator
Number of dilutive potential common shares									8,367,271	4,703,326	1,986,255
Restricted stock
Denominator
Number of dilutive potential common shares									473,336	650,002
Warrants
Denominator
Number of dilutive potential common shares									4,219,442	24,137,878	9,421,008
Preferred stock
Denominator
Number of dilutive potential common shares									5,554,594	10,972,859
Warrants issued in May, 2011
Denominator
Common stock warrants (in shares)													22,995,365
Number of warrants issued (in shares)												7,128,563
Number of warrants exercised (in shares)									22,776,023
Warrants issued in February, 2013
Denominator
Number of warrants issued (in shares)														23,637,500
Number of warrants exercised (in shares)									23,637,400
Warrants issued in January, 2014
Denominator
Number of warrants issued (in shares)															4,000,000
Number of warrants exercised (in shares)									0