Warrants - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant exercise price (in dollars per share)	$ 4.85	$ 4.85		$ 5.98
Warrant | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-cash expense (income)		$ 0.1	$ (5.3)
Issued in 2017 Series A Preferred Stock Offering
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrants issued to purchase common stock (in shares)	3,437,334	3,437,334
Warrant exercise price (in dollars per share)	$ 2.54	$ 2.54
Period after date of issuance to be exercised	6 months
Exercise period	5 years