Debt and Credit Arrangements Capped Call (Details) (4.75% Notes, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2011
4.75% Notes
Debt Instrument
Capped call, strike price	11.86	12.42	12.13
Capped call, cap price	17.43	18.26	17.83
Capped call, number of shares that may be purchased	16.9
Capped call, expiration date	Apr. 02, 2013
Capped call, cost of options		$ 22.8