Debt and Credit Arrangements Interest Rate Swaps (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Debt and Credit Arrangements [Abstract]
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	$ 175.0
Interest Rate Swap Agreements at Fair Value	2.8
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss)	(2.8)
Gain (Loss) on Cash Flow Hedge Ineffectiveness in Earnings	$ 0
Maximum Length of Time Hedged in Interest Rate Cash Flow Hedge	December 31, 2013