| Document and Entity Information | Aug. 03, 2020 |
| Cover [Abstract] | |
| Entity Registrant Name | Chubb Ltd |
| Amendment Flag | false |
| Entity Central Index Key | 0000896159 |
| Current Fiscal Year End Date | --12-31 |
| Document Type | 8-K |
| Document Period End Date | Aug. 3, 2020 |
| Entity Incorporation State Country Code | V8 |
| Entity File Number | 1-11778 |
| Entity Tax Identification Number | 98-0091805 |
| Entity Address, Address Line One | Baerengasse 32 |
| Entity Address, Postal Zip Code | 8001 |
| Entity Address, City or Town | Zurich |
| Entity Address, Country | CH |
| City Area Code | 41 (0)43 |
| Local Phone Number | 456 76 00 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Shares, par value CHF 24.15 per share |
| Trading Symbol | CB |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
