Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1.0	$ 0.7
Interest cost	1.2	1.1
Expected return on plan assets	(0.9)	(0.6)
Amortization of prior service costs	1.3	1.3
Amortization of actuarial loss	0.2	0
Periodic expense	2.8	2.5
Pension Benefits [Member] | Funded Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to unfunded pension plan	1.3
Expected to contribute to unfunded pension plans	5.0
Pension Benefits [Member] | Unfunded Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions to unfunded pension plan	1.0
Expected to contribute to unfunded pension plans	0.3
Other Postretirement Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	0	0
Interest cost	0.1	0.1
Expected return on plan assets	0	0
Amortization of prior service costs	0.1	0.1
Amortization of actuarial loss	0	0
Periodic expense	$ 0.2	$ 0.2