Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions	Mar. 31, 2017		Dec. 31, 2016		Mar. 31, 2016		Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	$ 99,491		$ 99,094
Cash	1,063	[1],[2]	985	[1],[3]	$ 1,091	[4]	$ 1,775	[4]
Insurance and reinsurance balances receivable	8,880		8,970
Reinsurance recoverable on losses and loss expenses	13,769		13,577
Reinsurance recoverable on policy benefits	187		182
Value of business acquired	345		355
Goodwill and other intangible assets	22,061		22,095
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	15,171		14,528
Total assets	160,967		159,786
Unpaid losses and loss expenses	60,579		60,540		60,206		37,303
Unearned premiums	14,857		14,779
Future policy benefits	5,086		5,036
Due to subsidiaries and affiliates, net	0		0
Affiliated notional cash pooling programs	0		0
Repurchase agreements	1,404		1,403
Short-term debt	300		500
Long-term debt	12,300		12,610
Trust preferred securities	308		308
Other liabilities	16,909		16,335
Total liabilities	111,743		111,511
Total shareholders' equity	49,224		48,275		45,897
Total liabilities and shareholders’ equity	160,967		159,786
Chubb Limited (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	25		27
Cash	6	[1],[2]	1	[1],[3]	2	[4]	1	[4]
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	39,156		38,408
Due from subsidiaries and affiliates, net	10,396		10,482
Other assets	4		3
Total assets	49,587		48,921
Unpaid losses and loss expenses	0		0
Unearned premiums	0		0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	0		0
Affiliated notional cash pooling programs	0	[2]	363	[3]
Repurchase agreements	0		0
Short-term debt	0		0
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	363		283
Total liabilities	363		646
Total shareholders' equity	49,224		48,275
Total liabilities and shareholders’ equity	49,587		48,921
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	304		485
Cash	1	[1],[2]	1	[1],[3]	3	[4]	2	[4]
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	50,242		49,509
Due from subsidiaries and affiliates, net	0		0
Other assets	519		436
Total assets	51,066		50,431
Unpaid losses and loss expenses	0		0
Unearned premiums	0		0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	10,028		10,209
Affiliated notional cash pooling programs	1,272	[2]	619	[3]
Repurchase agreements	0		0
Short-term debt	300		500
Long-term debt	12,289		12,599
Trust preferred securities	308		308
Other liabilities	1,699		1,582
Total liabilities	25,896		25,817
Total shareholders' equity	25,170		24,614
Total liabilities and shareholders’ equity	51,066		50,431
Other Chubb Limited Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	99,162		98,582
Cash	2,328	[1],[2]	1,965	[1],[3]	2,406	[4]	2,743	[4]
Insurance and reinsurance balances receivable	10,956		10,498
Reinsurance recoverable on losses and loss expenses	24,015		24,496
Reinsurance recoverable on policy benefits	1,145		1,153
Value of business acquired	345		355
Goodwill and other intangible assets	22,061		22,095
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	18,642		18,442
Total assets	178,654		177,586
Unpaid losses and loss expenses	70,269		70,683
Unearned premiums	18,343		18,538
Future policy benefits	6,044		6,007
Due to subsidiaries and affiliates, net	368		273
Affiliated notional cash pooling programs	0	[2]	0	[3]
Repurchase agreements	1,404		1,403
Short-term debt	0		0
Long-term debt	11		11
Trust preferred securities	0		0
Other liabilities	17,987		17,368
Total liabilities	114,426		114,283
Total shareholders' equity	64,228		63,303
Total liabilities and shareholders’ equity	178,654		177,586
Consolidating Adjustments and Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	0		0
Cash	(1,272)	[1],[2]	(982)	[1],[3]	$ (1,320)	[4]	$ (971)	[4]
Insurance and reinsurance balances receivable	(2,076)		(1,528)
Reinsurance recoverable on losses and loss expenses	(10,246)		(10,919)
Reinsurance recoverable on policy benefits	(958)		(971)
Value of business acquired	0		0
Goodwill and other intangible assets	0		0
Investments in subsidiaries	(89,398)		(87,917)
Due from subsidiaries and affiliates, net	(10,396)		(10,482)
Other assets	(3,994)		(4,353)
Total assets	(118,340)		(117,152)
Unpaid losses and loss expenses	(9,690)		(10,143)
Unearned premiums	(3,486)		(3,759)
Future policy benefits	(958)		(971)
Due to subsidiaries and affiliates, net	(10,396)		(10,482)
Affiliated notional cash pooling programs	(1,272)	[2]	(982)	[3]
Repurchase agreements	0		0
Short-term debt	0		0
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	(3,140)		(2,898)
Total liabilities	(28,942)		(29,235)
Total shareholders' equity	(89,398)		(87,917)
Total liabilities and shareholders’ equity	$ (118,340)		$ (117,152)

[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, 2017 and December 31, 2016, 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, 2017, 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, 2016, 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 March 31, 2016 and December 31, 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.