Pension and Other Postretirement Benefits (Tables)

3 Months Ended

Mar. 31, 2018

Compensation and Retirement Disclosure [Abstract]

Net periodic pension and OPEB cost

	Three Months Ended
	March 31, 2018									March 31, 2017
	Pension			OPEB			Consolidated			Pension			OPEB			Consolidated
	(In millions)
Service cost:
Service cost	$	1.4		$	2.3		$	3.7		$	1.8		$	2.6		$	4.4
Other pension and postretirement costs (benefits), net:
Interest cost	$	41.2		$	6.6		$	47.8		$	51.5		$	7.6		$	59.1
Expected return on plan assets	(59.7		)	—			(59.7		)	(70.7		)	0.1			(70.6		)
Amortization of prior service cost (benefit)	0.2			—			0.2			0.2			—			0.2
Amortization of net actuarial loss (gain)	1.9			(0.3		)	1.6			1.1			—			1.1
Curtailment and settlement loss (gain)	0.1			—			0.1			—			(2.9		)	(2.9		)
Less: expected participant contributions	—			—			—			(0.2		)	—			(0.2		)
Total other pension and postretirement cost (benefits), net	$	(16.3	)	$	6.3		$	(10.0	)	$	(18.1	)	$	4.8		$	(13.3	)
Net periodic pension and OPEB cost (benefit)	$	(14.9	)	$	8.6		$	(6.3	)	$	(16.3	)	$	7.4		$	(8.9	)