Pension and Other Postemployment Benefits (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Pension Plans [Member]
Components of Net Periodic Benefit Expense
Service cost	$ 5.3	$ 4.1
Interest cost	3.5	3.5
Expected return on plan assets	(1.4)	(1.4)
Amortization of prior service cost	2.4	2.2
Amortization of actuarial losses	3.1	2.4
Net periodic benefit expense	12.9	10.8
Employer contributions	0.7	0.5
Postemployment Arrangements [Member]
Components of Net Periodic Benefit Expense
Service cost	2.2	2.0
Interest cost	1.8	1.8
Amortization of prior service cost	1.8	1.4
Amortization of actuarial losses	0.5	0.5
Net periodic benefit expense	$ 6.3	$ 5.7