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Share-based compensation (Narrative) (Detail) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Unrecognized compensation expense related to the unvested share-based awards | $ 350,000,000 |  |
Weighted-average expected recognition period for the unrecognized compensation expense | 1 year 6 months |  |
Weighted average remaining contractual term for stock options outstanding | 5 years 7 months 6 days |  |
Weighted-average remaining contractual term for stock options exercisable | 4 years 4 months 24 days |  |
Cash received from exercise of stock options | $ 158,000,000 |  |
Restricted stock awards granted to non-management directors | 12,994 | 13,440 | 15,586
Amounts paid during period by employees for the purchase of shares under the ESPP | $ 54,000,000 | $ 48,000,000 | $ 47,000,000
Number of shares purchased during period by employees pursuant to the provisions of the ESPP | 305,604 | 271,650 | 315,405
Discounted purchase price from market price for the ESPP | 85.00% |  |
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Employee Subscription Rate for the ESPP | 10.00% |  |
Maximum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Employee Stock Purchase Plan Authorized Amount | $ 25,000 |  |
Performance Shares |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting period of award | 3 years |  |
Stock options |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting period of award | 3 years |  |
Stock option term in years | 10 years |  |
Restricted Stock Units (RSUs) |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Number of deferred restricted stock units | 100,965 |  |
ACE Limited 2004 Long-Term Incentive Plan [Member] | Restricted Stock Units (RSUs) |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting period of award | 1 year |  |
Chubb Limited 2016 Long-Term Incentive Plan, amended and restated [Member] | Restricted stock |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting period of award | 4 years |  |
Legacy Chubb Corp | Restricted Stock Units (RSUs) | Minimum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting period of award | 1 year |  |
Legacy Chubb Corp | Restricted Stock Units (RSUs) | Maximum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Vesting period of award | 3 years |  |
Common shares | Employee Stock [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Common shares authorized for issuance under plan | 6,500,000 |  |
Common Stock, Capital Shares Reserved for Future Issuance | 509,568 |  |
Common shares | Chubb Limited 2016 Long-Term Incentive Plan, amended and restated [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Common shares authorized for issuance under plan | 32,900,000 |  |
Common Stock, Capital Shares Reserved for Future Issuance | 12,533,303 |  |

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