Warrants - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant exercise price (in dollars per share)	$ 2.27	$ 2.27		$ 2.27		$ 7.14
Warrant | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-cash income		$ 3.0	$ 5.3	$ 10.5	$ 4.2
Issued with September 2016 Convertible Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants issued to purchase common stock (shares)	18,087,500	18,087,500		18,087,500
Warrant exercise price (in dollars per share)	$ 1.50	$ 1.50		$ 1.50
Period of time after issuance for warrants to become exercisable	6 months
Warrant exercise period	5 years