Employee Retirement Plans (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amounts Recognized in Other Comprehensive Income (Loss)
Actuarial gain (loss)	$ (71.9)	$ 83.7	$ (48.1)
Amortization of actuarial loss	2.1	4.9	3.2
Amortization of prior service cost	0	0.1	0.1
Curtailment	0.1	0	0
Total before income taxes	(69.7)	88.7	(44.8)
Income tax expense (benefit)	(25.9)	32.9	(16.7)
Net amount recognized in other comprehensive income (loss)	$ (43.8)	$ 55.8	$ (28.1)