Debt (Interest Rate Swaps) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Mark-to-market adjustments	$ 1.2		$ 1.2		$ (12.4)
Reduction of interest expense	3.5	3.4	7.1	6.9
Interest Rate Swaps [Member]
Principal amount of note	$ 750.0		$ 750.0