Pensions and other postretirement benefit plans - Retirement Plans (Details) - Pension benefits - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Funded plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Projected benefit obligation	$ 1,584,658	$ 2,927,968
Accumulated benefit obligation	1,583,793	2,925,870
Fair value of plan assets	1,672,568	3,157,553
Underfunded plans
Defined Benefit Plans and Other Postretirement Benefit Plans
Projected benefit obligation	57,522	75,356
Accumulated benefit obligation	57,522	75,356
Fair value of plan assets	$ 48,242	$ 61,400

Amount of projected benefit obligation for defined benefit pension plan with projected benefit obligation in excess of plan assets.

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- Definition

Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2417-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-Section 55
-Paragraph 17
-URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
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-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2417-114920

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- Definition

Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2417-114920

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e2417-114920

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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