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Retirement benefits - Assets Held In Retirement Benefit Accounts (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Pension benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 2,320,745 | $ 2,089,491 | $ 1,799,200
Other benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 239,311 | 219,873 | $ 200,831
Fair value measurements on a recurring basis | Pension benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 2,321,000 | 2,089,000 |
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 | 2,318,000 | 2,085,000 |
Fair value measurements on a recurring basis | Pension benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 1,546,000 | $ 1,376,000 |
Fair value measurements on a recurring basis | Pension benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption frequency, daily | 61.00% | 62.00% |
Redemption frequency, monthly | 39.00% | 38.00% |
Fair value measurements on a recurring basis | Pension benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 700,000 | $ 641,000 |
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 | 3,000 | 4,000 |
Fair value measurements on a recurring basis | Other benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 239,000 | 220,000 |
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 | 239,000 | 220,000 |
Fair value measurements on a recurring basis | Other benefits | Equity investments |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 173,000 | $ 158,000 |
Fair value measurements on a recurring basis | Other benefits | Non-U.S equity securities |  |  |
Fair value measurements on a recurring basis |  |  |
Redemption frequency, daily | 57.00% | 58.00% |
Redemption frequency, monthly | 43.00% | 42.00% |
Fair value measurements on a recurring basis | Other benefits | Fixed income securities |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | $ 63,000 | $ 58,000 |
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 | 432,000 | 368,000 |
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 | 188,000 | 172,000 |
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 | 830,000 | 734,000 |
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 | 363,000 |
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 | 53,000 | 46,000 |
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 | 24,000 | 22,000 |
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 | 84,000 | 77,000 |
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 | 53,000 |
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 | 1,610,000 | 1,404,000 |
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 | 1,449,000 | 1,274,000 |
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 | 431,000 | 368,000 |
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 | 188,000 | 172,000 |
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 | 830,000 | 734,000 |
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 | 146,000 | 105,000 |
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 |  |
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 | 25,000 |
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 | 220,000 | 199,000 |
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 | 161,000 | 145,000 |
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 | 53,000 | 46,000 |
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 | 24,000 | 22,000 |
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 | 84,000 | 77,000 |
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 | 56,000 | 51,000 |
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 |  |
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 | 248,000 | 258,000 |
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 | 1,000 | 0 |
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 | 1,000 | 0 |
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 | 247,000 | 258,000 |
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 |  |
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 | 2,000 | 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 | 2,000 | 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 |  |
Fair value measurements on a recurring basis | Net Asset Value | Pension benefits |  |  |
Fair value measurements on a recurring basis |  |  |
Fair value of plan assets | 460,000 | 423,000 |
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 | $ 96,000 | $ 102,000 |
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 | $ 96,000 | $ 102,000 |
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 | $ 307,000 | $ 278,000 |
Redemption notice period | 15 days | 15 days |
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 | $ 22,000 |  |
Unfunded commitments | $ 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 | $ 50,000 | $ 68,000 |
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 | $ 35,000 | $ 43,000 |
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 | $ 17,000 | $ 19,000 |
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 | $ 12,000 | $ 13,000 |
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 | $ 12,000 | $ 13,000 |
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 | $ 5,000 | $ 5,000 |
Redemption notice period | 15 days | 15 days |
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 |  |
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 | 3,000 | $ 4,000 |
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 | $ 0 | $ 1,000 |
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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