Pension and Postretirement Benefits (Components of net periodic benefit) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Benefits
Components of net periodic benefit cost
Service costs	$ 0.9	$ 1.0
Interest costs	0.7	0.5
Expected return on plan assets	(2.7)	(2.9)
Recognized net actuarial loss	0.6	0.1
Net periodic benefit (income) costs	$ (0.5)	$ (1.3)
Weighted average:
Discount rate for PBO	4.11%	3.52%
Discount rate for interest cost	3.72%	3.10%
Discount rate for service cost	4.10%	3.57%
Expected return on plan assets	8.25%	8.25%
Postretirement Benefits
Components of net periodic benefit cost
Service costs	$ 0.0	$ 0.0
Interest costs	0.1	0.1
Expected return on plan assets	0.0	0.0
Recognized net actuarial loss	0.0	0.0
Net periodic benefit (income) costs	$ 0.1	$ 0.1
Weighted average:
Discount rate for PBO	4.06%	3.32%
Discount rate for interest cost	3.72%	2.89%
Discount rate for service cost	4.34%	3.70%