| Document and Entity Information | Jul. 27, 2021 |
| Document Type | 8-K |
| Document Period End Date | Jul. 27, 2021 |
| Entity Registrant Name | Chubb Ltd |
| Entity Incorporation, State or Country Code | V8 |
| Entity File Number | 1-11778 |
| Entity Tax Identification Number | 98-0091805 |
| Entity Address, Address Line One | Baerengasse 32 |
| Entity Address, Address Line Two | CH |
| Entity Address, Postal Zip Code | 8001 |
| Entity Address, City or Town | Zurich |
| Entity Address, Country | CH |
| Country Region | 41 |
| City Area Code | (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 |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0000896159 |
| Common Class A [Member] | |
| Title of 12(b) Security | Common Shares, par value CHF 24.15 per share |
| Trading Symbol | CB |
| Security Exchange Name | NYSE |
| INA Senior Notes Due December 2024 [Member] | |
| Title of 12(b) Security | Guarantee of Chubb INA Holdings Inc. 0.30% Senior Notes due 2024 |
| Trading Symbol | CB/24A |
| Security Exchange Name | NYSE |
| INA Senior Notes Due June 2027 [Member] | |
| Title of 12(b) Security | Guarantee of Chubb INA Holdings Inc. 0.875% Senior Notes due 2027 |
| Trading Symbol | CB/27 |
| Security Exchange Name | NYSE |
| INA Senior Notes Due March 2028 [Member] | |
| Title of 12(b) Security | Guarantee of Chubb INA Holdings Inc. 1.55% Senior Notes due 2028 |
| Trading Symbol | CB/28 |
| Security Exchange Name | NYSE |
| INA Senior Notes Due December 2029 [Member] | |
| Title of 12(b) Security | Guarantee of Chubb INA Holdings Inc. 0.875% Senior Notes due 2029 |
| Trading Symbol | CB/29A |
| Security Exchange Name | NYSE |
| INA Senior Notes Due June 2031 [Member] | |
| Title of 12(b) Security | Guarantee of Chubb INA Holdings Inc. 1.40% Senior Notes due 2031 |
| Trading Symbol | CB/31 |
| Security Exchange Name | NYSE |
| INA Senior Notes Due March 2038 [Member] | |
| Title of 12(b) Security | Guarantee of Chubb INA Holdings Inc. 2.50% Senior Notes due 2038 |
| Trading Symbol | CB/38A |
| Security Exchange Name | NYSE |
