Debt (Interest Rate Swaps) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Notional Amount of Interest Rate Fair Value Hedge, Terminated			$ 750.0
Original Maturity of Interest Rate Swaps Terminated, Date Range Begin			Mar. 01, 2012
Original Maturity of Interest Rate Swaps Terminated, Date Range End			Apr. 01, 2013
Deferred Gain Loss On Discontinuation of Interest Rate Fair Value Hedge, Inception			22.7
Mark-to-market adjustments	(12.4)	31.7
Reduction of interest expense	13.6	21.8	31.5
Interest Rate Swap [Member]
Debt Instrument, Face Amount	750.0
4.70% senior notes due 2020 [Member] | Interest Rate Swap [Member]
Debt Instrument, Face Amount		$ 500.0