Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions	Sep. 30, 2016		Dec. 31, 2015		Sep. 30, 2015		Dec. 31, 2014	[4]
Condensed Financial Statements, Captions [Line Items]
Investments	$ 101,036		$ 66,251
Cash	870	[1],[2]	1,775	[1],[3]	$ 1,038	[4]	$ 655
Insurance and reinsurance balances receivable	8,493		5,323
Reinsurance recoverable on losses and loss expenses	13,448		11,386
Reinsurance recoverable on policy benefits	195		187
Value of business acquired	368		395
Goodwill and other intangible assets	22,472		5,683
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	14,928		11,306
Total assets	161,810		102,306
Unpaid losses and loss expenses	61,347		37,303
Unearned premiums	15,054		8,439
Future policy benefits	5,010		4,807
Due to subsidiaries and affiliates, net	0		0
Repurchase agreements	1,406		1,404
Short-term debt	500		0
Affiliated notional cash pooling programs	0		0
Long-term debt	12,621		9,389
Trust preferred securities	308		307
Other liabilities	17,192		11,522
Total liabilities	113,438		73,171
Total shareholders' equity	48,372		29,135		29,127
Total liabilities and shareholders’ equity	161,810		102,306
Consolidating Adjustments and Eliminations
Condensed Financial Statements, Captions [Line Items]
Investments	0		0
Cash	(1,296)	[1],[2]	(971)	[1],[3]	(1,161)	[4]	(555)
Insurance and reinsurance balances receivable	(2,899)		(752)
Reinsurance recoverable on losses and loss expenses	(10,194)		(8,738)
Reinsurance recoverable on policy benefits	(972)		(942)
Value of business acquired	0		0
Goodwill and other intangible assets	0		0
Investments in subsidiaries	(88,719)		(47,998)
Due from subsidiaries and affiliates, net	(11,186)		(2,444)
Other assets	(4,299)		(3,593)
Total assets	(119,565)		(65,438)
Unpaid losses and loss expenses	(9,535)		(8,187)
Unearned premiums	(3,719)		(1,804)
Future policy benefits	(972)		(942)
Due to subsidiaries and affiliates, net	(11,186)		(2,444)
Repurchase agreements	0		0
Short-term debt	0
Affiliated notional cash pooling programs	(1,296)	[2]	(971)	[3]
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	(4,138)		(3,092)
Total liabilities	(30,846)		(17,440)
Total shareholders' equity	(88,719)		(47,998)
Total liabilities and shareholders’ equity	(119,565)		(65,438)
Chubb Limited (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Investments	25		28
Cash	6	[1],[2]	1	[1],[3]	17	[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 and other intangible assets	0		0
Investments in subsidiaries	38,403		29,612
Due from subsidiaries and affiliates, net	11,186		644
Other assets	5		8
Total assets	49,625		30,293
Unpaid losses and loss expenses	0		0
Unearned premiums	0		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	927	[2]	882	[3]
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	326		276
Total liabilities	1,253		1,158
Total shareholders' equity	48,372		29,135
Total liabilities and shareholders’ equity	49,625		30,293
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Financial Statements, Captions [Line Items]
Investments	812		7,839
Cash	2	[1],[2]	2	[1],[3]	5	[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 and other intangible assets	0		0
Investments in subsidiaries	50,316		18,386
Due from subsidiaries and affiliates, net	0		1,800
Other assets	366		457
Total assets	51,496		28,484
Unpaid losses and loss expenses	0		0
Unearned premiums	0		0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	10,996		0
Repurchase agreements	0		0
Short-term debt	500
Affiliated notional cash pooling programs	369	[2]	89	[3]
Long-term debt	12,610		9,378
Trust preferred securities	308		307
Other liabilities	1,588		1,422
Total liabilities	26,371		11,196
Total shareholders' equity	25,125		17,288
Total liabilities and shareholders’ equity	51,496		28,484
Other Chubb Limited Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Investments	100,199		58,384
Cash	2,158	[1],[2]	2,743	[1],[3]	$ 2,177	[4]	$ 1,209
Insurance and reinsurance balances receivable	11,392		6,075
Reinsurance recoverable on losses and loss expenses	23,642		20,124
Reinsurance recoverable on policy benefits	1,167		1,129
Value of business acquired	368		395
Goodwill and other intangible assets	22,472		5,683
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	18,856		14,434
Total assets	180,254		108,967
Unpaid losses and loss expenses	70,882		45,490
Unearned premiums	18,773		10,243
Future policy benefits	5,982		5,749
Due to subsidiaries and affiliates, net	190		2,444
Repurchase agreements	1,406		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	19,416		12,916
Total liabilities	116,660		78,257
Total shareholders' equity	63,594		30,710
Total liabilities and shareholders’ equity	$ 180,254		$ 108,967

[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 September 30, 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 September 30, 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] 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 September 30, 2015 and December 31, 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.