Warrants - Warrant Activity (Details)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Increase (Decrease) in Warrants Outstanding [Roll Forward]
Beginning balance, number of warrants outstanding (shares) | shares	5,666,779
Number of warrants exercised during the period (shares) | shares	0
Number of warrants expired during the period (shares) | shares	(319,789)
Ending balance, number of warrants outstanding (shares) | shares	5,346,990
Beginning balance, weighted-average exercise price (usd per share) | $ / shares	$ 7.14
Weighted-average exercise price, warrants exercised during the period (usd per share) | $ / shares	0.00
Weighted-average exercise price, warrants expired during the period (usd per share) | $ / shares	6.25
Ending balance, weighted-average exercise price (usd per share) | $ / shares	$ 7.20