Consolidated Statements Of Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Treasury Stock, Common	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest
Noncontrolling interests (refer to Note 3 for balances associated with VIEs)							$ 0
Balance – beginning of period, net of tax at Dec. 31, 2021		$ 10,985	$ (7,464)	$ 8,478	$ 47,403	$ (1,074)
CB_Par value reduction		0		0
Treasury Stock, Retired, Cost Method, Amount		(639)	4,983		(4,344)
Common Shares repurchased			(2,815)
Net shares issued under employee share-based compensation plans			318	(185)
Exercise of stock options				(35)
Share-based compensation expense				205
Funding of dividends declared to Retained earnings				(1,034)
Net loss attributable to Chubb	$ 3,935				3,935
Funding of dividends declared from Additional paid-in capital					1,034
Dividends declared on Common Shares					(1,034)
Other Comprehensive Income (Loss), Net of Tax	(11,042)					(11,042)
Balance – end of period, net of tax at Sep. 30, 2022	47,675	10,346	(4,978)	7,429	46,994	(12,116)
Net loss attributable to noncontrolling interests	0						0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest							0
Noncontrolling interests (refer to Note 3 for balances associated with VIEs)							0
Balance – beginning of period, net of tax at Jun. 30, 2022		10,666	(6,794)	7,707	48,355	(8,666)
CB_Par value reduction		0		0
Treasury Stock, Retired, Cost Method, Amount		(320)	2,473		(2,153)
Common Shares repurchased			(685)
Net shares issued under employee share-based compensation plans			28	10
Exercise of stock options				(8)
Share-based compensation expense				66
Funding of dividends declared to Retained earnings				(346)
Net loss attributable to Chubb	792				792
Funding of dividends declared from Additional paid-in capital					346
Dividends declared on Common Shares					(346)
Other Comprehensive Income (Loss), Net of Tax	(3,450)					(3,450)
Balance – end of period, net of tax at Sep. 30, 2022	47,675	10,346	(4,978)	7,429	46,994	(12,116)
Net loss attributable to noncontrolling interests	0						0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest							0
Noncontrolling interests (refer to Note 3 for balances associated with VIEs)							0
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value							0
Total shareholders' equity	47,675
Noncontrolling interests (refer to Note 3 for balances associated with VIEs)	0						0
Total shareholders' equity	50,519
Balance – beginning of period, net of tax at Dec. 31, 2022	50,519	10,346	(5,113)	7,166	48,305	(10,185)
CB_Par value reduction		(9,759)		9,759
Treasury Stock, Retired, Cost Method, Amount		(346)	2,869		(2,523)
Common Shares repurchased			(1,758)
Net shares issued under employee share-based compensation plans			255	(203)
Exercise of stock options				(15)
Share-based compensation expense				230
Funding of dividends declared to Retained earnings				(1,050)
Net loss attributable to Chubb	5,728				5,728
Funding of dividends declared from Additional paid-in capital					1,050
Dividends declared on Common Shares					(1,050)
Other Comprehensive Income (Loss), Net of Tax	(1,409)					(1,333)
Balance – end of period, net of tax at Sep. 30, 2023	52,373	241	(3,747)	15,887	51,510	(11,518)
Net loss attributable to noncontrolling interests	(3)						(3)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest							(76)
Noncontrolling interests (refer to Note 3 for balances associated with VIEs)							0
Balance – beginning of period, net of tax at Jun. 30, 2023		241	(3,174)	16,163	49,467	(9,822)
CB_Par value reduction		0		0
Treasury Stock, Retired, Cost Method, Amount		0	0		0
Common Shares repurchased			(606)
Net shares issued under employee share-based compensation plans			33	3
Exercise of stock options				(2)
Share-based compensation expense				75
Funding of dividends declared to Retained earnings				(352)
Net loss attributable to Chubb	2,043				2,043
Funding of dividends declared from Additional paid-in capital					352
Dividends declared on Common Shares					(352)
Other Comprehensive Income (Loss), Net of Tax	(1,772)					(1,696)
Balance – end of period, net of tax at Sep. 30, 2023	52,373	$ 241	$ (3,747)	$ 15,887	$ 51,510	$ (11,518)
Net loss attributable to noncontrolling interests	(3)						(3)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest							(76)
Noncontrolling interests (refer to Note 3 for balances associated with VIEs)	5,131						5,131
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value							$ 5,210
Total shareholders' equity	$ 57,504