Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions	Jun. 30, 2017		Dec. 31, 2016		Jun. 30, 2016		Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	$ 100,208		$ 99,094
Cash	1,297	[1],[2]	985	[1],[3]	$ 1,011	[4]	$ 1,775	[4]
Insurance and reinsurance balances receivable	9,662		8,970
Reinsurance recoverable on losses and loss expenses	13,358		13,577
Reinsurance recoverable on policy benefits	198		182
Value of business acquired	337		355
Goodwill and other intangible assets	22,013		22,095
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	15,915		14,528
Total assets	162,988		159,786
Unpaid losses and loss expenses	60,394		60,540		60,819		37,303
Unearned premiums	15,289		14,779
Future policy benefits	5,190		5,036
Due to subsidiaries and affiliates, net	0		0
Affiliated notional cash pooling programs	0		0
Repurchase agreements	1,408		1,403
Short-term debt	922		500
Long-term debt	11,667		12,610
Trust preferred securities	308		308
Other liabilities	17,461		16,335
Total liabilities	112,639		111,511
Total shareholders' equity	50,349		48,275		47,226
Total liabilities and shareholders’ equity	162,988		159,786
Chubb Limited (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	23		27
Cash	0	[1],[2]	1	[1],[3]	1	[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	40,553		38,408
Due from subsidiaries and affiliates, net	10,251		10,482
Other assets	141		3
Total assets	50,968		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	193	[2]	363	[3]
Repurchase agreements	0		0
Short-term debt	0		0
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	426		283
Total liabilities	619		646
Total shareholders' equity	50,349		48,275
Total liabilities and shareholders’ equity	50,968		48,921
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	305		485
Cash	167	[1],[2]	1	[1],[3]	207	[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	49,982		49,509
Due from subsidiaries and affiliates, net	0		0
Other assets	289		436
Total assets	50,743		50,431
Unpaid losses and loss expenses	0		0
Unearned premiums	0		0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	9,939		10,209
Affiliated notional cash pooling programs	0	[2]	619	[3]
Repurchase agreements	0		0
Short-term debt	922		500
Long-term debt	11,656		12,599
Trust preferred securities	308		308
Other liabilities	1,582		1,582
Total liabilities	24,407		25,817
Total shareholders' equity	26,336		24,614
Total liabilities and shareholders’ equity	50,743		50,431
Other Chubb Limited Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	99,880		98,582
Cash	1,323	[1],[2]	1,965	[1],[3]	1,825	[4]	2,743	[4]
Insurance and reinsurance balances receivable	11,699		10,498
Reinsurance recoverable on losses and loss expenses	24,118		24,496
Reinsurance recoverable on policy benefits	1,205		1,153
Value of business acquired	337		355
Goodwill and other intangible assets	22,013		22,095
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	19,527		18,442
Total assets	180,102		177,586
Unpaid losses and loss expenses	70,460		70,683
Unearned premiums	18,876		18,538
Future policy benefits	6,197		6,007
Due to subsidiaries and affiliates, net	312		273
Affiliated notional cash pooling programs	0	[2]	0	[3]
Repurchase agreements	1,408		1,403
Short-term debt	0		0
Long-term debt	11		11
Trust preferred securities	0		0
Other liabilities	18,639		17,368
Total liabilities	115,903		114,283
Total shareholders' equity	64,199		63,303
Total liabilities and shareholders’ equity	180,102		177,586
Consolidating Adjustments and Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	0		0
Cash	(193)	[1],[2]	(982)	[1],[3]	$ (1,022)	[4]	$ (971)	[4]
Insurance and reinsurance balances receivable	(2,037)		(1,528)
Reinsurance recoverable on losses and loss expenses	(10,760)		(10,919)
Reinsurance recoverable on policy benefits	(1,007)		(971)
Value of business acquired	0		0
Goodwill and other intangible assets	0		0
Investments in subsidiaries	(90,535)		(87,917)
Due from subsidiaries and affiliates, net	(10,251)		(10,482)
Other assets	(4,042)		(4,353)
Total assets	(118,825)		(117,152)
Unpaid losses and loss expenses	(10,066)		(10,143)
Unearned premiums	(3,587)		(3,759)
Future policy benefits	(1,007)		(971)
Due to subsidiaries and affiliates, net	(10,251)		(10,482)
Affiliated notional cash pooling programs	(193)	[2]	(982)	[3]
Repurchase agreements	0		0
Short-term debt	0		0
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	(3,186)		(2,898)
Total liabilities	(28,290)		(29,235)
Total shareholders' equity	(90,535)		(87,917)
Total liabilities and shareholders’ equity	$ (118,825)		$ (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 June 30, 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 June 30, 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 June 30, 2016 and December 31, 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.