Employee Retirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Other disclosures
Number of multiemployer plans with significant underfunded liabilities	1
Pension Benefits
Components of Net Periodic Benefit Cost:
Company contributions	$ 20.3	$ 44.8
Pension Benefits - U.S.
Components of Net Periodic Benefit Cost:
Service cost	6.3	6.2
Interest cost	6.5	6.5
Expected return on plan assets	(7.3)	(7.1)
Net amortizations	2.8	2.0
Settlement loss		0.3
Net pension/postretirement expense	8.3	7.9
Pension Benefits - Non-U.S.
Components of Net Periodic Benefit Cost:
Service cost	0.3	1.7
Interest cost	2.3	2.8
Expected return on plan assets	(3.0)	(3.1)
Net amortizations		(0.3)
Net pension/postretirement expense	(0.4)	1.1
Pension Benefits - U.K.
Components of Net Periodic Benefit Cost:
Discretionary cash contributions to qualified pension plan	3.2	12.3
Unamortized prior service cost			13.1
Postretirement Benefits (U.S.)
Components of Net Periodic Benefit Cost:
Service cost	0.1	0.1
Interest cost	0.2	0.2
Net pension/postretirement expense	$ 0.3	$ 0.3
Key officer postretirement car benefit plan | Minimum
Components of Net Periodic Benefit Cost:
Service period (in years)			20
Retirement age (in years)			58