Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions	Mar. 31, 2016		Dec. 31, 2015		Mar. 31, 2015		Dec. 31, 2014	[4]
Condensed Financial Statements, Captions [Line Items]
Investments	$ 97,586		$ 66,251
Cash	1,091	[1],[2]	1,775	[1],[3]	$ 948	[4]	$ 655
Insurance and reinsurance balances receivable	7,692		5,323
Reinsurance recoverable on losses and loss expenses	12,891		11,386
Reinsurance recoverable on policy benefits	185		187
Value of business acquired	390		395
Goodwill	23,359		5,683
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	13,450		11,306
Total assets	156,644		102,306
Unpaid losses and loss expenses	60,206		37,303
Unearned premiums	14,896		8,439
Future policy benefits	4,869		4,807
Due to subsidiaries and affiliates, net	0		0
Repurchase Agreements	1,403		1,404
Short-term debt	500		0
Affiliated notional cash pooling programs	0		0
Long-term debt	12,636		9,389
Trust preferred securities	308		307
Other liabilities	15,929		11,522
Total liabilities	110,747		73,171
Total shareholders' equity	45,897		29,135		29,702
Total liabilities and shareholders’ equity	156,644		102,306
Chubb Limited (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Investments	29		28
Cash	2	[1],[2]	1	[1],[3]	2	[4]	0
Insurance and reinsurance balances receivable	0		0
Reinsurance recoverable on losses and loss expenses	0		0
Reinsurance recoverable on policy benefits	0		0
Value of business acquired	0		0
Goodwill	0		0
Investments in subsidiaries	35,426		29,612
Due from subsidiaries and affiliates, net	11,267		644
Other assets	4		8
Total assets	46,728		30,293
Unpaid losses and loss expenses	0		0
Unearned premiums			0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	0		0
Repurchase Agreements	0		0
Short-term debt	0
Affiliated notional cash pooling programs	521	[2]	882	[3]
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	310		276
Total liabilities	831		1,158
Total shareholders' equity	45,897		29,135
Total liabilities and shareholders’ equity	46,728		30,293
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Investments	643		7,839
Cash	3	[1],[2]	2	[1],[3]	366	[4]	1
Insurance and reinsurance balances receivable	0		0
Reinsurance recoverable on losses and loss expenses	0		0
Reinsurance recoverable on policy benefits	0		0
Value of business acquired	0		0
Goodwill	0		0
Investments in subsidiaries	49,240		18,386
Due from subsidiaries and affiliates, net	0		1,800
Other assets	503		457
Total assets	50,389		28,484
Unpaid losses and loss expenses	0		0
Unearned premiums			0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	11,199		0
Repurchase Agreements	0		0
Short-term debt	500
Affiliated notional cash pooling programs	799	[2]	89	[3]
Long-term debt	12,625		9,378
Trust preferred securities	308		307
Other liabilities	1,575		1,422
Total liabilities	27,006		11,196
Total shareholders' equity	23,383		17,288
Total liabilities and shareholders’ equity	50,389		28,484
Other Chubb Limited Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Investments	96,914		58,384
Cash	2,406	[1],[2]	2,743	[1],[3]	658	[4]	1,209
Insurance and reinsurance balances receivable	10,884		6,075
Reinsurance recoverable on losses and loss expenses	22,065		20,124
Reinsurance recoverable on policy benefits	1,144		1,129
Value of business acquired	390		395
Goodwill	23,359		5,683
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	17,291		14,434
Total assets	174,453		108,967
Unpaid losses and loss expenses	68,917		45,490
Unearned premiums	18,522		10,243
Future policy benefits	5,828		5,749
Due to subsidiaries and affiliates, net	68		2,444
Repurchase Agreements	1,403		1,404
Short-term debt	0
Affiliated notional cash pooling programs	0	[2]	0	[3]
Long-term debt	11		11
Trust preferred securities	0		0
Other liabilities	18,421		12,916
Total liabilities	113,170		78,257
Total shareholders' equity	61,283		30,710
Total liabilities and shareholders’ equity	174,453		108,967
Consolidating Adjustments and Eliminations
Condensed Financial Statements, Captions [Line Items]
Investments	0		0
Cash	(1,320)	[1],[2]	(971)	[1],[3]	$ (78)	[4]	$ (555)
Insurance and reinsurance balances receivable	(3,192)		(752)
Reinsurance recoverable on losses and loss expenses	(9,174)		(8,738)
Reinsurance recoverable on policy benefits	(959)		(942)
Value of business acquired	0		0
Goodwill	0		0
Investments in subsidiaries	(84,666)		(47,998)
Due from subsidiaries and affiliates, net	(11,267)		(2,444)
Other assets	(4,348)		(3,593)
Total assets	(114,926)		(65,438)
Unpaid losses and loss expenses	(8,711)		(8,187)
Unearned premiums	(3,626)		(1,804)
Future policy benefits	(959)		(942)
Due to subsidiaries and affiliates, net	(11,267)		(2,444)
Repurchase Agreements	0		0
Short-term debt	0
Affiliated notional cash pooling programs	(1,320)	[2]	(971)	[3]
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	(4,377)		(3,092)
Total liabilities	(30,260)		(17,440)
Total shareholders' equity	(84,666)		(47,998)
Total liabilities and shareholders’ equity	$ (114,926)		$ (65,438)

[1] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various Chubb entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual Chubb accounts are translated daily into a single currency and pooled on a notional basis. Individual Chubb entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At March 31, 2016 and December 31, 2015, 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. Various Chubb entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual Chubb accounts are translated daily into a single currency and pooled on a notional basis. Individual Chubb entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At March 31, 2016, 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. Various Chubb entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual Chubb accounts are translated daily into a single currency and pooled on a notional basis. Individual Chubb entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At December 31, 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[4] maintains two notional multicurrency cash pools (Pools) with a third-party bank. Various Chubb entities participate in one or the other of the Pools, pursuant to which credit and debit balances in individual Chubb accounts are translated daily into a single currency and pooled on a notional basis. Individual Chubb entities are permitted to overdraw on their individual accounts provided the overall Pool balances do not fall below zero. At March 31, 2015 and December 31, 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.