Stockholders' Equity (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Total Share-based Compensation expense
Total share-based compensation	$ 4.5	$ 8.5	$ 17.7	$ 22.0
2011 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	0.7		2.5
2010 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	0.8	0.8	4.6	2.3
2009 Two-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation		3.2		7.2
2009 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	1.2	2.1	3.6	4.8
SLO Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	(0.3)	0.2	0.3	0.6
Other long-term share-based incentive compensation programs [Member]
Total Share-based Compensation expense
Total share-based compensation	$ 2.1	$ 2.2	$ 6.7	$ 7.1