Restructuring (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Dec. 31, 2011 2011 Restructuring Plan [Member]	Dec. 31, 2011 2011 Restructuring Plan [Member]	Dec. 31, 2010 2010 Restructuring Plan [Member]	Dec. 31, 2011 2010 Restructuring Plan [Member]	Dec. 31, 2009 2009 Restructuring Plan [Member]
Restructuring Cost and Reserve [Line Items]
Employee separation and other costs related to one time employee termination benefits, after tax							$ 11.4		$ 10.2
Remaining liability related to restructuring charge					7.4	7.4
Cash payments related to restructuring charges						3.0
Severance costs					12.0
Severance costs after tax					8.1
Total cost of restructuring		10.0		16.7			16.7		15.4
Reversal of restructuring costs	$ 1.1		$ 1.1			$ 1.6		$ 2.6