Retirement benefits (Tables)

6 Months Ended

Jun. 30, 2021

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)	2021		2020	2021	2020	2021	2020
Three months ended June 30,
Service cost	$	—	—	2.5	3.0	2.5	3.0
Interest cost on projected benefit obligation	5.3		6.7	3.1	2.9	8.4	9.6
Return on assets – expected	(11.9)		(11.6)	(3.1)	(3.1)	(15.0)	(14.7)
Amortization of losses	8.6		7.2	1.7	1.2	10.3	8.4
Amortization of prior service credit	—		—	(0.1)	—	(0.1)	—
Curtailment gain	—		—	(0.6)	—	(0.6)	—
Settlement loss	—		—	0.3	0.1	0.3	0.1
Net periodic pension cost	$	2.0	2.3	3.8	4.1	5.8	6.4
Six months ended June 30,
Service cost	$	—	—	4.7	5.9	4.7	5.9
Interest cost on projected benefit obligation	10.6		13.3	6.0	5.3	16.6	18.6
Return on assets – expected	(23.7)		(23.1)	(6.2)	(5.7)	(29.9)	(28.8)
Amortization of losses	17.0		14.1	3.3	2.4	20.3	16.5
Amortization of prior service cost	—		—	(0.1)	—	(0.1)	—
Curtailment gain	—		—	(0.6)	—	(0.6)	—
Settlement loss	—		—	0.7	0.5	0.7	0.5
Net periodic pension cost	$	3.9	4.3	7.8	8.4	11.7	12.7

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)	2021		2020	2021	2020	2021	2020
Three months ended June 30,
Service cost	$	—	—	0.1	0.1	0.1	0.1
Interest cost on accumulated postretirement benefit obligations	2.4		3.1	0.8	1.0	3.2	4.1
Return on assets – expected	(3.0)		(3.2)	—	—	(3.0)	(3.2)
Amortization of losses	4.2		4.1	2.3	2.1	6.5	6.2
Amortization of prior service cost	(1.1)		(1.1)	(0.2)	(0.2)	(1.3)	(1.3)
Net periodic postretirement cost	$	2.5	2.9	3.0	3.0	5.5	5.9
Six months ended June 30,
Service cost	$	—	—	0.1	0.1	0.1	0.1
Interest cost on accumulated postretirement benefit obligations	4.9		6.4	1.6	1.9	6.5	8.3
Return on assets – expected	(6.1)		(6.5)	—	—	(6.1)	(6.5)
Amortization of losses	9.0		8.1	4.4	4.1	13.4	12.2
Amortization of prior service cost	(2.3)		(2.3)	(0.2)	(0.2)	(2.5)	(2.5)
Net periodic postretirement cost	$	5.5	5.7	5.9	5.9	11.4	11.6