Warrants - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Level 3 | Warrants
Class of Warrant or Right [Line Items]
Non-cash expense (income) resulting from change in estimated fair value	$ (2.9)	$ (3.9)	$ 1.1