Stockholders' Equity (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Total Share-based Compensation expense
Total share-based compensation	$ 25.0	$ 30.6	$ 38.8
Associated tax benefits recognized	9.3	11.3	14.5
2011 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	3.0
2010 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	6.0	3.0
2009 Two-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	(0.7)	10.4	14.1
2009 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	7.4	7.0	9.4
SLO Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	0.3	1.0	2.9
Other long-term share-based incentive compensation programs [Member]
Total Share-based Compensation expense
Total share-based compensation	$ 9.0	$ 9.2	$ 12.4