Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2018

Defined Benefit Pension Plans

Components of Net Periodic Defined Benefit Cost

The components of our net periodic defined benefit pension cost are presented in the table below.

	Three months ended June 30,						Six months ended June 30,
	2017			2018			2017			2018
	(In millions)
Service cost	$	2.8		$	2.9		$	5.5		$	5.9
Interest cost		3.9			4.0			7.7			8.0
Expected return on plan assets		(3.2	)		(3.8	)		(6.4	)		(7.8	)
Amortization of unrecognized prior service cost		.1			—			.2			.1
Recognized actuarial losses		3.7			3.9			7.3			7.7
Total	$	7.3		$	7.0		$	14.3		$	13.9

OPEB

Components of Net Periodic Defined Benefit Cost

The components of our net periodic other postretirement benefit cost are presented in the table below.

	Three months ended June 30,						Six months ended June 30,
	2017			2018			2017			2018
	(In millions)
Service cost	$	.1		$	.1		$	.1		$	.1
Interest cost		.1			—			.2			.1
Amortization of prior service credit		(.3	)		(.2	)		(.5	)		(.5	)
Recognized actuarial gains		—			(.1	)		(.1	)		(.1	)
Total	$	(.1	)	$	(.2	)	$	(.3	)	$	(.4	)