Stockholders' Equity (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Total Share-based Compensation expense
Total share-based compensation	$ 7.4	$ 6.0	$ 13.2	$ 13.5
2011 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	0.9	0	1.8	0
2010 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	3.0	0.7	3.8	1.5
2009 Two-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	0	2.0	0	4.0
2009 Three-year PSU Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	0.9	1.4	2.4	2.7
SLO Awards [Member]
Total Share-based Compensation expense
Total share-based compensation	0.2	0.1	0.6	0.4
Other long-term share-based incentive compensation programs [Member]
Total Share-based Compensation expense
Total share-based compensation	$ 2.4	$ 1.8	$ 4.6	$ 4.9