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Long-Term Employee Benefit Liabilities - Future Benefit Payments (Detail) $ in Millions | Dec. 31, 2020 USD ($)
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Defined Benefit Plan Disclosure [Line Items] |
Expected employer contributions - 2021 | $ 24
2021 | 35
2022 | 37
2023 | 39
2024 | 43
2025 | 50
Thereafter | 283
Total | 487
Pension Plan, Defined Benefit [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected employer contributions - 2021 | 13
2021 | 24
2022 | 25
2023 | 25
2024 | 26
2025 | 27
Thereafter | 151
Total | 278
Termination and Long Service Arrangements [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected employer contributions - 2021 | 10
2021 | 10
2022 | 11
2023 | 13
2024 | 15
2025 | 21
Thereafter | 124
Total | 194
Retirement Medical Benefits Plans [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Expected employer contributions - 2021 | 1
2021 | 1
2022 | 1
2023 | 1
2024 | 2
2025 | 2
Thereafter | 8
Total | $ 15

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