Shareholders' Equity and Stock-Based Compensation (Details 6) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			1 Months Ended		6 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Common Stock In Treasury	Feb. 29, 2012 Common Stock In Treasury	Jun. 30, 2012 Common Stock In Treasury	Dec. 31, 2012 Common Stock In Treasury
Authorized repurchase amount under a written trading plan					$ 350.0
Common stock repurchased (in shares)	3,606,000			2,600,000		1,000,000	3,606,000
Total cash consideration paid for common stock repurchased	$ 245.6			$ 170.6		$ 75.0	$ 245.6
Preferred Stock
Authorized no par value preferred stock (in shares)	3,000,000	3,000,000	3,000,000