Severance And Restructuring Charges (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Dec. 31, 2010	Dec. 31, 2011
Restructuring Cost and Reserve [Line Items]
Pre-tax charge	$ 6.2
Pre-tax severance charge		9.1
Cash outlays associated with severance	1.3
Reversal of severance charges			0.9
Accrued liabilities	3.4
Severance And Restructuring Charges [Member]
Restructuring Cost and Reserve [Line Items]
Cash outlays associated with severance	0.2
Accrued liabilities	1.3		2.6
Facility Closure Cost [Member]
Restructuring Cost and Reserve [Line Items]
Pre-tax charge	2.6
Severance And Related Expense [Member]
Restructuring Cost and Reserve [Line Items]
Pre-tax charge	$ 3.6