Retirement and Postretirement Plans (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Components of net periodic benefit cost (income)
Service cost	$ 0.8	$ 0.8	$ 0.5
Interest cost	5.2	6.0	6.5
Expected return on plan assets	(7.6)	(7.3)	(6.3)
Amortization of unrecognized loss	0.5	0.6	1.6
Net periodic pension cost (income) before settlements, curtailments and special termination benefits	(1.1)	0.1	2.3
Settlement loss (gain)	0.5	(0.1)
Special termination benefits expense	0.8	1.9	1.2
Total net periodic benefit cost	$ 0.2	$ 1.9	$ 3.5
Weighted average discount rate assumptions used to determine benefit obligations
Discount rate (as a percent)	4.38%	4.94%
Weighted average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	4.94%	5.16%
Expected long-term rate of return on plan assets (as a percent)	5.75%	5.75%