Pension and Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2018

Retirement Benefits [Abstract]

Components of net periodic benefit cost

The components of net periodic benefit (income) costs recognized during interim periods were as follows:

	Pension Benefits												Postretirement Benefits
	Three Months Ended June 30,						Six Months Ended June 30,						Three Months Ended June 30,				Six Months Ended June 30,
	2018			2017			2018			2017			2018		2017		2018			2017
	(In millions)
Service costs	$	1.0		$	0.7		$	2.0		$	1.3		$	—	$	—	$	—		$	—
Interest costs	0.6			0.4			1.1			0.9			—		—		0.1			0.1
Expected return on plan assets	(2.9		)	(2.4		)	(5.8		)	(4.8		)	—		—		—			—
Recognized net actuarial loss	0.1			0.3			0.2			0.6			—		0.1		—			0.1
Net periodic benefit (income) costs	$	(1.2	)	$	(1.0	)	$	(2.5	)	$	(2.0	)	$	—	$	0.1	$	0.1		$	0.2
Weighted average:
Discount rate for PBO							3.52		%	3.91		%					3.32		%	3.63		%
Discount rate for interest cost							3.10		%	3.20		%					2.89		%	2.92		%
Discount rate for service cost							3.57		%	3.98		%					3.70		%	4.12		%
Expected return on plan assets							8.25		%	8.25		%