Debt (Interest Rate Swaps) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Mark-to-market adjustments	$ 4.8		$ 4.8		$ 11.8
Reduction of interest expense	4.3	$ 3.4	10.9	$ 10.5
Interest Rate Swaps [Member]
Principal amount of note	$ 596.0		$ 596.0