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Retirement benefits - Assets Held In Retirement Benefit Accounts (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Pension benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 1,806,379 | $ 2,320,745 | $ 2,089,491
Other benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 190,547 | 239,311 | $ 219,873
Fair value measurements on a recurring basis | Pension benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 1,806,000 | 2,321,000 |
Fair value measurements on a recurring basis | Pension benefits | Total, excluding cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 1,805,000 | 2,318,000 |
Fair value measurements on a recurring basis | Pension benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 1,189,000 | $ 1,546,000 |
Fair value measurements on a recurring basis | Pension benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption frequency, daily | 59.00% | 61.00% |
Redemption frequency, monthly | 41.00% | 39.00% |
Fair value measurements on a recurring basis | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 534,000 | $ 700,000 |
Fair value measurements on a recurring basis | Pension benefits | Cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 1,000 | 3,000 |
Fair value measurements on a recurring basis | Other benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 191,000 | 239,000 |
Fair value measurements on a recurring basis | Other benefits | Total, excluding cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 191,000 | 239,000 |
Fair value measurements on a recurring basis | Other benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 134,000 | $ 173,000 |
Fair value measurements on a recurring basis | Other benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption frequency, daily | 56.00% | 57.00% |
Redemption frequency, monthly | 44.00% | 43.00% |
Fair value measurements on a recurring basis | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 53,000 | $ 63,000 |
Fair value measurements on a recurring basis | Other benefits | Cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Pension benefits | U.S. equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 387,000 | 432,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Pension benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 147,000 | 188,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Pension benefits | U.S. equity index and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 580,000 | 830,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets |  | 393,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 83,000 |  |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Pension benefits | Fixed income mutual and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 225,000 |  |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Other benefits | U.S. equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 48,000 | 53,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Other benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 18,000 | 24,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Other benefits | U.S. equity index and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 58,000 | 84,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets |  | 58,000 |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 |  |
Fair value measurements on a recurring basis | Fair Value, Inputs, Level 1, 2 and 3 | Other benefits | Fixed income mutual and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 50,000 |  |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Total, excluding cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 1,364,000 | 1,610,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 1,114,000 | 1,449,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | U.S. equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 387,000 | 431,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 147,000 | 188,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | U.S. equity index and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 580,000 | 830,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 235,000 | 146,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 10,000 |  |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Fixed income mutual and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 225,000 |  |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Private equity at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Pension benefits | Cash equivalents, fund and at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 15,000 | 15,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Total, excluding cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 177,000 | 220,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 124,000 | 161,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | U.S. equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 48,000 | 53,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 18,000 | 24,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | U.S. equity index and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 58,000 | 84,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 50,000 | 56,000 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 |  |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Fixed income mutual and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 50,000 |  |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Private equity at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Quoted prices in active markets for identical assets (Level 1) | Other benefits | Cash equivalents, fund and at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 3,000 | 3,000 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | Total, excluding cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 73,000 | 248,000 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 1,000 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | U.S. equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 1,000 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | U.S. equity index and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 73,000 | 247,000 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 73,000 |  |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Pension benefits | Private equity at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Other benefits | Total, excluding cash, receivables and payables, net |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 2,000 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Other benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Other benefits | U.S. equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Other benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Other benefits | U.S. equity index and exchange-traded funds |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 2,000 |
Fair value measurements on a recurring basis | Significant other observable inputs (Level 2) | Other benefits | Private equity at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | 0 |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 368,000 | 460,000 |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 75,000 | $ 96,000 |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Non-U.S equity securities | Minimum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 5 days | 5 days |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Non-U.S equity securities | Maximum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 30 days | 30 days |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Non-U.S. equity investments at net asset value (NAV) |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 75,000 | $ 96,000 |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 226,000 | $ 307,000 |
Redemption notice period | 15 days | 15 days |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Fixed income investments at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 226,000 |  |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Private equity at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 34,000 | $ 22,000 |
Unfunded commitments | $ 56,000 | 66,000 |
Dissolution written notice period | 6 months |  |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Cash equivalents, fund and at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 48,000 | 50,000 |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Cash equivalents |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 33,000 | $ 35,000 |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Cash equivalents | Minimum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 0 days | 0 days |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits | Cash equivalents | Maximum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 1 day | 1 day |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 14,000 | $ 17,000 |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 10,000 | $ 12,000 |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Non-U.S equity securities | Minimum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 5 days | 5 days |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Non-U.S equity securities | Maximum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 30 days | 30 days |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Non-U.S. equity investments at net asset value (NAV) |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 10,000 | $ 12,000 |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 3,000 | $ 5,000 |
Redemption notice period | 15 days | 15 days |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Fixed income investments at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 3,000 |  |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Private equity at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 0 | $ 0 |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Cash equivalents, fund and at NAV |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 4,000 | 3,000 |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Cash equivalents |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 1,000 | $ 0 |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Cash equivalents | Minimum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 0 days | 0 days |
Fair value measurements on a recurring basis | Net Asset Value | Other benefits | Cash equivalents | Maximum |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption notice period | 1 day | 1 day |

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- Definition Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 4: 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 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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