Schedule II (STATEMENTS OF CASH FLOWS - Parent Company Only) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net cash flows from operating activities		$ 6,342		$ 5,480		$ 4,503
Payment Of Contributions To Subsidiary		0		0
Dividends paid on Common Shares		(1,354)		(1,337)		(1,308)
Common Shares repurchased		(1,530)		(1,044)		(801)
Net proceeds from (payments to) affiliated notional cash pooling programs		0		0	[1]	0
Net cash flows (used for) from financing activities		(151)		(1,991)		(2,319)
Effect of foreign currency rate changes on cash and restricted cash		20		(65)		1
Cash and restricted cash – beginning of year		1,247	[2]	728
Cash and restricted cash – end of year		1,537	[3]	1,247	[2]	728
Chubb limited (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Net cash flows from operating activities	[4]	412		256		781
Payment Of Contributions To Subsidiary		(1,000)		(1,475)
Net cash flows used for investing activities		(1,000)		(1,475)		0
Dividends paid on Common Shares		(1,354)		(1,337)		(1,308)
Common Shares repurchased		(327)		0		0
Payments To From Affiliates		2,301		2,519		892
Net proceeds from (payments to) affiliated notional cash pooling programs	[5]	(35)		35		(363)
Net cash flows (used for) from financing activities		585		1,217		(779)
Effect of foreign currency rate changes on cash and restricted cash		4		0		0
Net increase (decrease) in cash and restricted cash		1		(2)		2
Cash and restricted cash – beginning of year		1	[2]	3		1
Cash and restricted cash – end of year		2	[3]	1	[2]	3
Cash dividend paid by Affiliates		$ 200		$ 75		$ 450

[1] Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2018 and 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[2] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2018, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information.

[4] Includes cash dividends received from subsidiaries of $200 million, $75 million, and $450 million in 2019, 2018, and 2017, respectively.

[5] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information.