Stock-Based Compensation - Summary of Stock Option Activity (Details) (USD $)	12 Months Ended
	Dec. 31, 2014
Options
Outstanding at beginning of period	106,544
Granted	1,448,751
Forfeited	(157,102)
Expired	(14,714)
Outstanding at end of period	1,383,479
Exercisable at end of period	339,110
Vested and expected to vest at end of period	1,327,485
Weighted Average Exercise Price
Outstanding at beginning of period	$ 28.90
Granted	$ 3.30
Forfeited	$ 3.84
Expired	$ 10.54
Outstanding at end of period	$ 5.13
Exercisable at end of period	$ 11.42
Vested and expected to vest at end of period	$ 5.22
Weighted-Average Remaining Contractual Life, Outstanding at end of period	9 years 2 months 12 days
Weighted-Average Remaining Contractual Life, Exercisable at end of period	8 years 1 month 6 days
Weighted-Average Remaining Contractual Life, Vested and expected to vest at end of period	9 years 2 months 12 days
Intrinsic Value, Outstanding at end of period	$ 18,600
Intrinsic Value, Vested and expected to vest at end of period	$ 17,700