Fair Value Measurement - Accumulated Derivative Instruments (Loss) Gain (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cumulative Changes in Derivative Net Gain (Loss) [Roll Forward]
Balance at beginning of period	$ (12.5)	$ (1.3)	$ (5.7)
Reclassification to earnings	11.7	0.8	2.5
Current period change in fair value	(12.7)	(12.0)	1.9
Balance at end of period	(13.5)	$ (12.5)	$ (1.3)
Expected reclassification of pre-tax losses in the next twelve months from ACOL to earnings	$ 12.3