Pensions and Postretirement Benefits Other Than Pensions (Schedule of Net Periodic Postretirement Benefit Cost) (Details) - Postretirement Benefit Costs [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Service cost	$ 3.1	$ 3.7	$ 4.4
Interest cost	15.7	17.5	22.6
Prior service gains, net amortization of	(8.6)	(8.9)	(8.9)
Plan net actuarial losses, net amortization of	0.1	0.1	0.1
Net periodic benefit cost	10.3	12.4	18.2
Net periodic benefit cost after net curtailment and settlement (gains) losses	10.3	12.4	18.2
Segment, Continuing Operations [Member]
Net periodic benefit cost after net curtailment and settlement (gains) losses
Segment, Discontinued Operations [Member]
Net periodic benefit cost after net curtailment and settlement (gains) losses	$ 1.6	$ 4.1	$ 7.2