Retirement benefits (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The components of net periodic pension cost for our pension plans were as follows:

	U.S. Plans					Non-U.S. Plans				Total
(In millions)	2018			2017		2018		2017		2018		2017
Three months ended March 31,
Service cost	$	—		—		3.0		2.9		3.0		2.9
Interest cost on projected benefit obligation	8.0			8.8		4.0		4.8		12.0		13.6
Return on assets – expected	(13.4		)	(13.3	)	(2.9	)	(2.4	)	(16.3	)	(15.7	)
Amortization of losses	7.1			6.3		1.3		1.3		8.4		7.6
Amortization of prior service cost	—			—		0.2		0.2		0.2		0.2
Settlement loss	—			—		0.5		0.3		0.5		0.3
Net periodic pension cost	$	1.7		1.8		6.1		7.1		7.8		8.9

Schedule of Costs of Retirement Plans

The components of net periodic postretirement cost related to retirement benefits other than pensions were as follows:

	UMWA Plans					Black Lung and Other Plans		Total
(In millions)	2018			2017		2018	2017	2018		2017
Three months ended March 31,
Interest cost on accumulated postretirement benefit obligations	$	4.5		4.4		0.7	0.7	5.2		5.1
Return on assets – expected	(4.2		)	(4.2	)	—	—	(4.2	)	(4.2	)
Amortization of losses	5.5			4.4		1.2	0.9	6.7		5.3
Amortization of prior service (credit) cost	(1.1		)	(1.1	)	0.3	0.5	(0.8	)	(0.6	)
Net periodic postretirement cost	$	4.7		3.5		2.2	2.1	6.9		5.6