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Unpaid losses and loss expenses Unpaid losses and loss expenses (Details) (Supplementary PPD) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2020 USD ($)
North America Commercial P&C Insurance - Workers' Compensation [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | $ (350)
North America Commercial P&C Insurance - Workers' Compensation [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (94)
North America Commercial P&C Insurance - Workers' Compensation [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (256)
North America Commercial P&C Insurance - Liability [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (293)
North America Commercial P&C Insurance - Liability [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (176)
North America Commercial P&C Insurance - Liability [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (117)
North America Commercial P&C Insurance - Other Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | 42
North America Commercial P&C Insurance - Other Casualty [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | 23
North America Commercial P&C Insurance - Other Casualty [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | 19
North America Commercial P&C Insurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (35)
North America Commercial P&C Insurance - Non-Casualty [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | 2
North America Commercial P&C Insurance - Non-Casualty [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (37)
North America Personal P&C Insurance [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | 84
North America Personal P&C Insurance [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (1)
North America Personal P&C Insurance [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | 85
Overseas General Insurance - Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (50)
Overseas General Insurance - Casualty [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (59)
Overseas General Insurance - Casualty [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | 9
Overseas General Insurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (77)
Overseas General Insurance - Non-Casualty [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (8)
Overseas General Insurance - Non-Casualty [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (69)
Global Reinsurance - Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (22)
Global Reinsurance - Casualty [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (10)
Global Reinsurance - Casualty [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | (12)
Global Reinsurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (2)
Global Reinsurance - Non-Casualty [Member] | prior to 2011 |
Supplementary PPD [Line Items] |
Short-Duration PPD | 0
Global Reinsurance - Non-Casualty [Member] | 2011 - 2020 |
Supplementary PPD [Line Items] |
Short-Duration PPD | $ (2)

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