Pension and Other Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.5	$ 3.1	$ 4.5	$ 10.1
Interest cost	9.3	10.5	27.8	31.5
Expected return on plan assets	(8.6)	(11.3)	(25.6)	(33.3)
Amortization of prior service cost	0.0	0.1	0.0	0.1
Amortization of actuarial losses	3.0	3.4	8.5	10.4
Curtailment and settlement losses	0.0	0.0	0.5	0.0
NET PERIODIC BENEFIT COST	5.2	5.8	15.7	18.8
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.0	0.0	0.0	0.0
Interest cost	0.4	0.3	0.8	0.9
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of prior service cost	(0.3)	(0.3)	(0.7)	(0.7)
Amortization of actuarial losses	0.0	0.0	0.0	0.0
Curtailment and settlement losses	0.0	0.0	0.0	0.0
NET PERIODIC BENEFIT COST	$ 0.1	$ 0.0	$ 0.1	$ 0.2