Schedule II Schedule II (STATEMENTS OF OPERATIONS - Parent Company Only) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Equity in net income of subsidiaries and affiliates	[1]									$ 617	$ 514	$ 418
Total revenues		$ 8,738	$ 9,045	$ 8,527	$ 7,876	$ 7,626	$ 8,750	$ 8,510	$ 7,831	34,186	32,717	32,243
Administrative and other (income) expense										3,030	2,886	2,833
Business Combination, Integration Related Costs										23	59	310
Income tax expense (benefit)										795	695	(139)
Total expenses										28,937	28,060	28,521
Net income		$ 1,173	$ 1,091	$ 1,150	$ 1,040	$ 355	$ 1,231	$ 1,294	$ 1,082	4,454	3,962	3,861
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest										7,521	1,242	4,718
Chubb limited (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Investment income, including intercompany interest income										227	305	336
Equity in net income of subsidiaries and affiliates										4,307	3,753	3,640
Total revenues										4,534	4,058	3,976
Administrative and other (income) expense										65	63	63
Business Combination, Integration Related Costs										1	14	32
Income tax expense (benefit)										14	19	20
Total expenses										80	96	115
Net income										4,454	3,962	3,861
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest										$ 7,521	$ 1,242	$ 4,718

[1] Equity in net income of partially-owned entities includes $74 million, $43 million, and $3 million attributable to our investments in Huatai (Huatai Group, Huatai P&C, and Huatai Life) for the years ended December 31, 2019, 2018, and 2017, respectively.