Equity Financings and Warrants - Summary of Warrants by Year of Expiration (Details)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Class Of Warrant Or Right [Line Items]
Number of Warrants | shares	3,739,948
Weighted Average Exercise Price | $ / shares	$ 9.70
2016
Class Of Warrant Or Right [Line Items]
Year of Expiration	2016
Number of Warrants | shares	82,816
Weighted Average Exercise Price | $ / shares	$ 68.19
2017
Class Of Warrant Or Right [Line Items]
Year of Expiration	2017
Number of Warrants | shares	24,124
Weighted Average Exercise Price | $ / shares	$ 17.89
2018
Class Of Warrant Or Right [Line Items]
Year of Expiration	2018
Number of Warrants | shares	963,153
Weighted Average Exercise Price | $ / shares	$ 11.77
2019
Class Of Warrant Or Right [Line Items]
Year of Expiration	2019
Number of Warrants | shares	224,323
Weighted Average Exercise Price | $ / shares	$ 15.73
2020
Class Of Warrant Or Right [Line Items]
Year of Expiration	2020
Number of Warrants | shares	44,299
Weighted Average Exercise Price | $ / shares	$ 15.96
2022
Class Of Warrant Or Right [Line Items]
Year of Expiration	2022
Number of Warrants | shares	2,401,233
Weighted Average Exercise Price | $ / shares	$ 6.10