Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions	Jun. 30, 2019		Dec. 31, 2018		Jun. 30, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	$ 105,739		$ 100,968
Cash	1,270		1,247
Restricted cash	98		93
Insurance and reinsurance balances receivable	10,935		10,075
Reinsurance recoverable on losses and loss expenses	15,445		15,993
Reinsurance recoverable on policy benefits	201		202
Operating Lease, Right-of-Use Asset	601
Value of business acquired	280		295
Goodwill and other intangible assets	21,566		21,414
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	0		0
Other assets	18,982		17,484
Total assets	174,516		167,771
Unpaid losses and loss expenses	63,205		62,960		$ 62,778	$ 63,179
Unearned premiums	16,403		15,532
Future policy benefits	5,568		5,506
Due to subsidiaries and affiliates, net	0		0
Affiliated notional cash pooling programs	0		0
Operating Lease, Liability	642
Repurchase agreements	1,416		1,418
Short-term debt	9		509
Long-term debt	13,371		12,087
Trust preferred securities	308		308
Other liabilities	20,434		19,139
Total liabilities	120,714		117,459
Total shareholders' equity	53,802		50,312		$ 50,971
Total liabilities and shareholders’ equity	174,516		167,771
Chubb Limited (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	0		0
Cash	1	[1]	1	[2]
Restricted cash	0		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	47,983		43,531
Due from subsidiaries and affiliates, net	6,289		7,074
Other assets	5		3
Total assets	54,278		50,609
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	177	[1]	35	[2]
Repurchase agreements	0		0
Short-term debt	0		0
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	299		262
Total liabilities	476		297
Total shareholders' equity	53,802		50,312
Total liabilities and shareholders’ equity	54,278		50,609
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	235		214
Cash	1	[1]	2	[2]
Restricted cash	0		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	51,972		50,209
Due from subsidiaries and affiliates, net	0		0
Other assets	449		1,007
Total assets	52,657		51,432
Unpaid losses and loss expenses	0		0
Unearned premiums	0		0
Future policy benefits	0		0
Due to subsidiaries and affiliates, net	6,228		7,672
Affiliated notional cash pooling programs	180	[1]	617	[2]
Repurchase agreements	0		0
Short-term debt	0		500
Long-term debt	13,370		12,086
Trust preferred securities	308		308
Other liabilities	1,774		2,545
Total liabilities	21,860		23,728
Total shareholders' equity	30,797		27,704
Total liabilities and shareholders’ equity	52,657		51,432
Other Chubb Limited Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	105,504		100,754
Cash	1,625	[1]	1,896	[2]
Restricted cash	98		93
Insurance and reinsurance balances receivable	12,735		11,861
Reinsurance recoverable on losses and loss expenses	25,297		26,422
Reinsurance recoverable on policy benefits	297		306
Value of business acquired	280		295
Goodwill and other intangible assets	21,566		21,414
Investments in subsidiaries	0		0
Due from subsidiaries and affiliates, net	(61)		598
Other assets	20,266		18,102
Total assets	187,607		181,741
Unpaid losses and loss expenses	72,693		72,857
Unearned premiums	17,624		16,611
Future policy benefits	5,664		5,610
Due to subsidiaries and affiliates, net	0		0
Affiliated notional cash pooling programs	0	[1]	0	[2]
Repurchase agreements	1,416		1,418
Short-term debt	9		9
Long-term debt	1		1
Trust preferred securities	0		0
Other liabilities	21,042		19,199
Total liabilities	118,449		115,705
Total shareholders' equity	69,158		66,036
Total liabilities and shareholders’ equity	187,607		181,741
Consolidating Adjustments and Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	0		0
Cash	(357)	[1]	(652)	[2]
Restricted cash	0		0
Insurance and reinsurance balances receivable	(1,800)		(1,786)
Reinsurance recoverable on losses and loss expenses	(9,852)		(10,429)
Reinsurance recoverable on policy benefits	(96)		(104)
Value of business acquired	0		0
Goodwill and other intangible assets	0		0
Investments in subsidiaries	(99,955)		(93,740)
Due from subsidiaries and affiliates, net	(6,228)		(7,672)
Other assets	(1,738)		(1,628)
Total assets	(120,026)		(116,011)
Unpaid losses and loss expenses	(9,488)		(9,897)
Unearned premiums	(1,221)		(1,079)
Future policy benefits	(96)		(104)
Due to subsidiaries and affiliates, net	(6,228)		(7,672)
Affiliated notional cash pooling programs	(357)	[1]	(652)	[2]
Repurchase agreements	0		0
Short-term debt	0		0
Long-term debt	0		0
Trust preferred securities	0		0
Other liabilities	(2,681)		(2,867)
Total liabilities	(20,071)		(22,271)
Total shareholders' equity	(99,955)		(93,740)
Total liabilities and shareholders’ equity	$ (120,026)		$ (116,011)

[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, 2019, 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 December 31, 2018, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.