Pension and Savings Plans (Details) (Pension Plans, Defined Benefit [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans, Defined Benefit [Member]
Components of net periodic pension costs
Service cost for benefits earned	$ 1.7	$ 1.5	$ 1.4
Interest cost on projected benefit obligation	49.8	50.5	51.3
Expected return on plan assets	(64.4)	(58.3)	(60.9)
Amortization of prior service cost	1.0	1.4	1.4
Amortization of actuarial loss	30.1	21.9	1.9
Net periodic (benefit) cost	$ 18.2	$ 17.0	$ (4.9)