Document and Entity Information - SFr / shares	3 Months Ended
	Mar. 31, 2021	Apr. 16, 2021	Dec. 31, 2020
Document Type	10-Q
Document Period End Date	Mar. 31, 2021
Document Quarterly Report	true
Document Transition Report	false
Entity Registrant Name	Chubb Ltd
Entity Central Index Key	0000896159
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity File Number	1-11778
Entity Incorporation, State or Country Code	V8
Entity Tax Identification Number	98-0091805
Entity Address, Address Line One	Baerengasse 32
Entity Address, City or Town	Zurich
Entity Address, Country	CH
Entity Address, Postal Zip Code	8001
Country Region	41
City Area Code	(0)43
Local Phone Number	456 76 00
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Shell Company	false
Entity Emerging Growth Company	false
Common Shares, par value	SFr 24.15		SFr 24.15
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Common Shares Outstanding		449,690,575
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
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 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 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 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
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