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Unpaid losses and loss expenses (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2004
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ (926) | $ (395) | $ (792) |  |
Prior Period Development, net Adjustments |  | $ 60 | $ 19 | $ 53 |  |
Prior Period Development Percentage Opening Net Unpaid Reserves | [1] | 1.70% | 0.80% | 1.60% |  |
Incurred activity |  | $ 21,980 | $ 21,710 | $ 18,730 |  |
Liability for Claims and Claims Adjustment Expense |  | 72,943 | 67,811 | 62,690 | $ 62,960 |
Brandywine Run-off [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Incurred activity |  | 745 |  |  |  |
Reinsurance coverage to Century provided by ACE INA under XOL |  | 800 |  |  |  |
Statutory capital and surplus |  | 25 |  |  |  |
Dividend retention fund established by INA Financial Corporation |  | 50 |  |  |  |
Required minimum balance under the dividend retention fund |  | 50 |  |  |  |
Contributions to the dividend retention fund |  | 50 | 250 |  |  |
Minimum contribution from the dividend retention fund to Century not required for XOL agreement |  | 200 |  |  |  |
Dividend Retention Fund Contribution to XOL |  | 18 | 302 |  |  |
Aggregate reinsurance balances ceded by active ACE companies to Century |  | 1,800 | 1,600 |  |  |
Liability for Claims and Claims Adjustment Expense |  | 2,200 | 2,100 |  |  |
Surplus note |  |  |  |  |  | $ 100
Century X O L Reinsurance Coverage, Statutory-Basis Remaining Limit |  | $ 55 |  |  |  |
Westchester and Brandywine Run-off [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
NICO pro-rata share of reinsurance protection (percent) |  | 75.00% |  |  |  |
NICO retention for losses and loss expenses incurred on or before 12/31/1996 |  | $ 721 |  |  |  |
NICO reinsurance protection on losses and loss expenses incurred on or before 12/31/1996, net of retenion |  | 1,000 |  |  |  |
NICO reinsurance protection on losses and loss expenses |  | 359 |  |  |  |
Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (44) | (313) | (642) |  |
Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (882) | (82) | (150) |  |
Boy Scouts of America Agreement in Principle [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense |  | 800 |  |  |  |
Reinsurance Recoverable and Previously Carried Reserves |  | 425 |  |  |  |
North America Commercial P&C Insurance [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (762) | $ (702) | $ (649) |  |
Prior Period Development, net Adjustments | [2] | $ 79 |  |  |  |
Prior Period Development Percentage Opening Net Unpaid Reserves | [1] | 1.40% | 1.40% | 1.30% |  |
North America Commercial P&C Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ (482) | $ (672) | $ (668) |  |
Prior Period Development, net Adjustments |  | 69 |  |  |  |
North America Commercial P&C Insurance [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (280) | (30) | 19 |  |
Prior Period Development, net Adjustments |  | 10 |  |  |  |
North America Commercial P&C Insurance [Member] | Multi-Line [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 46 | 26 |  |  |
North America Commercial P&C Insurance [Member] | Workers' Compensation Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (363) |  |  |
North America Commercial P&C Insurance [Member] | Auto Liability | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | 77 |  |  |
North America Commercial P&C Insurance [Member] | COVID-19 [Member] | Management Liability [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (303) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2014 and prior [Member] | Commercial Excess and Umbrella [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (83) |  |  |
North America Commercial P&C Insurance [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Foreign Casualty Line [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (40) |  |  |
North America Commercial P&C Insurance [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Surety Product Line [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (31) |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2017 and prior [Member] | Multi-Line [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (43) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2017 and prior [Member] | Environmental lines [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (40) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2016 and prior [Member] | Professional Errors and Omissions Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (67) |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2016 and prior [Member] | Multi-Line [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (41) |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2016 and prior [Member] | Workers' Compensation Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (260) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2016 and prior [Member] | Environmental lines [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (43) |  |  |
North America Commercial P&C Insurance [Member] | Accident Year 2015 and prior [Member] | Management Liability [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (231) |  |  |
North America Commercial P&C Insurance [Member] | Accident Year 2017 to 2019 [Member] | Auto Liability | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 71 |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2016 - 2019 [Member] | Commercial Excess and Umbrella [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 32 |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2016 - 2019 [Member] | Medical Portfolios [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | 64 |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2018 - 2019 [Member] | Accident and Health [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (37) |  |  |
North America Commercial P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Workers' Compensation Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (62) |  |  |
North America Commercial P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Property and Inland Marine | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | 21 |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2017 - 2019 | General Liability Coverages | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | 48 |  |  |
North America Commercial P&C Insurance [Member] | Accident Years 2019 - 2020 | Accident and Health [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (45) |  |  |  |
North America Commercial P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Surety Product Line [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (35) |  |  |  |
North America Commercial P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Management Liability [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (278) |  |  |  |
North America Commercial P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Workers' Compensation Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (36) |  |  |  |
North America Commercial P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | COVID-19 [Member] | Management Liability [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (256) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2016, 2017, and 2020 [Member] | Professional Errors and Omissions Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (59) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2004 and prior [Member] | Other [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 26 |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2017 and 2018 [Member] | Medical Portfolios [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 66 |  |  |  |
North America Commercial P&C Insurance [Member] | Accident Years 2019 and 2020 | Property and Inland Marine | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (164) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2018 - 2020 [Member] | Surety Product Line [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (89) |  |  |  |
North America Commercial P&C Insurance [Member] | Accident years 2018 - 2020 [Member] | First Party Cyber risk | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 42 |  |  |  |
North America Personal P&C Insurance [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ (305) | $ 63 | $ (95) |  |
Prior Period Development Percentage Opening Net Unpaid Reserves | [1] | 0.60% | 0.10% | 0.20% |  |
North America Personal P&C Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 0 | $ 0 | $ 0 |  |
North America Personal P&C Insurance [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (305) | 63 | (95) |  |
Prior Period Development, net Adjustments |  | (1) |  |  |  |
North America Personal P&C Insurance [Member] | Personal Excess [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (22) |  |  |
North America Personal P&C Insurance [Member] | Accident Year 2017 to 2019 [Member] | Homeowners and Valuables [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | 84 |  |  |
North America Personal P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Homeowners and Valuables [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (253) |  |  |  |
North America Personal P&C Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Auto Liability | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (43) |  |  |  |
North America Agricultural Insurance [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 10 | $ (10) | $ (80) |  |
Prior Period Development Percentage Opening Net Unpaid Reserves | [1] | 0.00% | 0.00% | 0.20% |  |
North America Agricultural Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 0 | $ 0 | $ 0 |  |
North America Agricultural Insurance [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 10 | (10) | (80) |  |
Prior Period Development, net Adjustments |  | (28) |  |  |  |
Overseas General Insurance [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (441) | $ (150) | $ (92) |  |
Prior Period Development, net Adjustments |  | $ 7 |  |  |  |
Prior Period Development Percentage Opening Net Unpaid Reserves | [1] | 0.80% | 0.30% | 0.20% |  |
Overseas General Insurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ (106) | $ (49) | $ (68) |  |
Prior Period Development, net Adjustments |  | 0 |  |  |  |
Overseas General Insurance [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (335) | (101) | (24) |  |
Prior Period Development, net Adjustments |  | 7 |  |  |  |
Overseas General Insurance [Member] | Casualty Lines [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (67) | (94) |  |  |
Overseas General Insurance [Member] | Financial [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (14) | 80 |  |  |
Overseas General Insurance [Member] | COVID-19 [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (127) |  |  |  |
Overseas General Insurance [Member] | Accident years 2017 and prior [Member] | Casualty Lines [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (95) |  |  |  |
Overseas General Insurance [Member] | Accident years 2016 and prior [Member] | Casualty Lines [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (143) |  |  |
Overseas General Insurance [Member] | Accident Year 2015 and prior [Member] | Financial [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (61) |  |  |
Overseas General Insurance [Member] | Accident Year 2017 to 2019 [Member] | Casualty Lines [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | 49 |  |  |
Overseas General Insurance [Member] | Accident years 2016 - 2019 [Member] | Financial [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | 141 |  |  |
Overseas General Insurance [Member] | Accident years 2018 - 2019 [Member] | Accident and Health [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (21) |  |  |
Overseas General Insurance [Member] | Accident years 2018 - 2019 [Member] | Political Risk | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (22) |  |  |
Overseas General Insurance [Member] | Accident years 2012 through 2019 | Marine [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  |  | (69) |  |  |
Overseas General Insurance [Member] | Accident Years 2019 - 2020 | Accident and Health [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (111) |  |  |  |
Overseas General Insurance [Member] | Accident Years 2019 - 2020 | Property and Casualty [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (67) |  |  |  |
Overseas General Insurance [Member] | Accident Years 2019 - 2020 | Consumer [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (71) |  |  |  |
Overseas General Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | COVID-19 [Member] | Financial [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (104) |  |  |  |
Overseas General Insurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | COVID-19 [Member] | Accident and Health [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (20) |  |  |  |
Overseas General Insurance [Member] | Accident years 2018 - 2020 [Member] | Casualty Lines [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 28 |  |  |  |
Overseas General Insurance [Member] | Accident years 2018 - 2020 [Member] | Marine [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | (62) |  |  |  |
Overseas General Insurance [Member] | Accident years 2011 - 2020 [Member] | Financial [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 90 |  |  |  |
Overseas General Insurance - Casualty [Member] | Europe [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Loss by Geographic Percentage |  | 46.00% |  |  |  |
Overseas General Insurance - Non-Casualty [Member] | Europe and Asia [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Loss by Geographic Percentage |  | 33.00% |  |  |  |
Global Reinsurance Non-Casualty [Member] | accident year 2012 and after |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Loss by Geographic Percentage |  | 79.00% |  |  |  |
Global Reinsurance Non-Casualty [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Loss by Geographic Percentage |  | 54.00% |  |  |  |
Global Reinsurance Non-Casualty [Member] | Accident year 2013 to 2021 |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Loss by Geographic Percentage |  | 83.00% |  |  |  |
Global Reinsurance [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 3 | $ (29) | $ (29) |  |
Prior Period Development, net Adjustments |  | $ 3 |  |  |  |
Prior Period Development Percentage Opening Net Unpaid Reserves | [1] | 0.00% | 0.10% | 0.10% |  |
Global Reinsurance [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ (25) | $ (25) | $ (59) |  |
Prior Period Development, net Adjustments |  | 3 |  |  |  |
Global Reinsurance [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 28 | (4) | 30 |  |
Prior Period Development, net Adjustments |  | 0 |  |  |  |
Global Reinsurance [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Property catastrophe [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 34 |  |  |  |
Corporate Segment [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 569 | $ 433 | $ 153 |  |
Prior Period Development Percentage Opening Net Unpaid Reserves | [1] | 1.10% | 0.90% | 0.30% |  |
Corporate Segment [Member] | Discontinued Operations [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 43 | $ 38 |  |  |
Corporate Segment [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 569 | 433 | $ 153 |  |
Prior Period Development, net Adjustments |  | 0 |  |  |  |
Corporate Segment [Member] | Short Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 0 | 0 | $ 0 |  |
Corporate Segment [Member] | Other [Member] | Other [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 14 | 27 |  |  |
Corporate Segment [Member] | Other [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | 417 | 254 |  |  |
Corporate Segment [Member] | Asbestos & Environmental [Member] | Long Tail [Member] |  |  |  |  |  |
Liability for Claims and Claims Adjustment Expense [Line Items] |  |  |  |  |  |
Net Prior Period Development |  | $ 83 | $ 106 |  |  |
[1] | Calculated based on the beginning of period consolidated net unpaid losses and loss expenses.
[2] | Includes premium returns associated with our Alternative Risk Solutions business, which is excluded from the triangles.

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