Debt (Interest Rate Swaps) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Mark-to-market adjustments	$ 12.7		$ 12.7		$ 11.8
Reduction of interest expense	3.3	$ 3.5	6.7	$ 7.1
Interest Rate Swaps [Member]
Principal amount of note	$ 596.0		$ 596.0