Pension and Other Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated pension plan contributions in current year	$ 44.1
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	60.0
Defined Benefit Plans, Estimated Future Employer Contributions, Year Two	75.0
Net periodic benefit cost (income) [Abstract]
Service cost	0.7	$ 0.7
Interest cost	27.0	32.0
Expected return on assets	(37.6)	(42.9)
Amortization of prior service cost (credit)	1.2	1.3
Amortization of (gain) loss	2.7	7.0
Net periodic benefit cost (income)	(6.0)	(1.9)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net periodic benefit cost (income) [Abstract]
Service cost	1.2	1.2
Interest cost	4.3	5.0
Amortization of prior service cost (credit)	(14.6)	(15.1)
Amortization of (gain) loss	(1.1)	(1.1)
Net periodic benefit cost (income)	$ (10.2)	$ (10.0)