Debt (Interest Rate Swaps) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Mark-to-market adjustments	$ 7.1		$ 12.4
Reduction of interest expense	3.6	3.5
Interest Rate Swaps [Member]
Principal amount of note	$ 750.0