Employee Retirement Plans (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Amounts Recognized in Other Comprehensive Income (Loss)
Actuarial gain (loss)	$ (48.1)	$ (47.3)	$ 11.9
Amortization of actuarial loss	3.2	1.7	1.9
Amortization of prior service cost	0.1	0.1	0.1
Other	0	0	(0.2)
Settlements	0	0	0.2
Total before income taxes	(44.8)	(45.5)	13.9
Income tax expense (benefit)	(16.7)	(16.9)	5.2
Net amount recognized in other comprehensive income (loss)	$ (28.1)	$ (28.6)	$ 8.7