Information provided in connection with outstanding debt of subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		$ 100,968		$ 102,444
Cash		1,247	[1]	728	[2]	$ 985
Restricted Cash		93	[1]	123	[2]	103
Insurance and reinsurance balances receivable		10,075		9,334
Reinsurance recoverable on losses and loss expenses		15,993		15,034
Reinsurance Recoverable Future Policy Benefits		202		184
Value of business acquired		295		326		355	$ 395
Goodwill		21,414		22,054
Investments in subsidiaries		0		0
Due from subsidiaries and affiliates, net		0		0
Other assets		17,484		16,795
Total assets		167,771		167,022
Unpaid losses and loss expenses		62,960		63,179		60,540	37,303
Unearned premiums		15,532		15,216
Future policy benefits		5,506		5,321
Due to subsidiaries and affiliates, net		0		0
Affiliated notional cash pooling program		0	[1]	0	[2]
Repurchase agreements		1,418		1,408
Short-term debt		509		1,013
Long-term debt		12,087		11,556
Trust preferred securities		308		308
Other liabilities		19,139		17,849
Total liabilities		117,459		115,850
Total shareholders' equity		50,312		51,172
Total liabilities and shareholders’ equity		167,771		167,022
Consolidating Adjustments
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		0		0
Cash		(652)	[1]	(115)	[2]
Restricted Cash		0	[1]	0	[2]
Insurance and reinsurance balances receivable		(1,786)		(1,486)
Reinsurance recoverable on losses and loss expenses		(10,429)		(12,480)
Reinsurance Recoverable Future Policy Benefits		(104)		(1,010)
Value of business acquired		0		0
Goodwill		0		0
Investments in subsidiaries		(93,740)		(93,074)
Due from subsidiaries and affiliates, net		(7,672)		(9,639)
Other assets		(1,628)		(4,073)
Total assets		(116,011)		(121,877)
Unpaid losses and loss expenses		(9,897)		(11,588)
Unearned premiums		(1,079)		(3,659)
Future policy benefits		(104)		(1,010)
Due to subsidiaries and affiliates, net		(7,672)		(9,639)
Affiliated notional cash pooling program		(652)	[1]	(115)	[2]
Repurchase agreements		0		0
Short-term debt		0		0
Long-term debt		0		0
Trust preferred securities		0		0
Other liabilities		(2,867)		(2,792)
Total liabilities		(22,271)		(28,803)
Total shareholders' equity		(93,740)		(93,074)
Total liabilities and shareholders’ equity		(116,011)		(121,877)
Chubb limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		0		0
Cash		1	[1]	3	[2]	$ 1	$ 1
Restricted Cash		0	[1]	0	[2]
Insurance and reinsurance balances receivable		0		0
Reinsurance recoverable on losses and loss expenses		0		0
Reinsurance Recoverable Future Policy Benefits		0		0
Value of business acquired		0		0
Goodwill		0		0
Investments in subsidiaries		43,531		41,909
Due from subsidiaries and affiliates, net		7,074		9,639
Other assets		3		3
Total assets		50,609		51,554
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 program	[3]	35	[1]	0	[2]
Repurchase agreements		0		0
Short-term debt		0		0
Long-term debt		0		0
Trust preferred securities		0		0
Other liabilities		262		382
Total liabilities		297		382
Total shareholders' equity		50,312		51,172
Total liabilities and shareholders’ equity		50,609		51,554
Chubb INA Holdings Inc. (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		214		168
Cash		2	[1]	1	[2]
Restricted Cash		0	[1]	0	[2]
Insurance and reinsurance balances receivable		0		0
Reinsurance recoverable on losses and loss expenses		0		0
Reinsurance Recoverable Future Policy Benefits		0		0
Value of business acquired		0		0
Goodwill		0		0
Investments in subsidiaries		50,209		51,165
Due from subsidiaries and affiliates, net		0		0
Other assets		1,007		287
Total assets		51,432		51,621
Unpaid losses and loss expenses		0		0
Unearned premiums		0		0
Future policy benefits		0		0
Due to subsidiaries and affiliates, net		7,672		9,432
Affiliated notional cash pooling program		617	[1]	115	[2]
Repurchase agreements		0		0
Short-term debt		500		1,013
Long-term debt		12,086		11,546
Trust preferred securities		308		308
Other liabilities		2,545		1,411
Total liabilities		23,728		23,825
Total shareholders' equity		27,704		27,796
Total liabilities and shareholders’ equity		51,432		51,621
Other Chubb Limited Subsidiaries and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Investments		100,754		102,276
Cash		1,896	[1]	839	[2]
Restricted Cash		93	[1]	123	[2]
Insurance and reinsurance balances receivable		11,861		10,820
Reinsurance recoverable on losses and loss expenses		26,422		27,514
Reinsurance Recoverable Future Policy Benefits		306		1,194
Value of business acquired		295		326
Goodwill		21,414		22,054
Investments in subsidiaries		0		0
Due from subsidiaries and affiliates, net		598		0
Other assets		18,102		20,578
Total assets		181,741		185,724
Unpaid losses and loss expenses		72,857		74,767
Unearned premiums		16,611		18,875
Future policy benefits		5,610		6,331
Due to subsidiaries and affiliates, net		0		207
Affiliated notional cash pooling program		0	[1]	0	[2]
Repurchase agreements		1,418		1,408
Short-term debt		9		0
Long-term debt		1		10
Trust preferred securities		0		0
Other liabilities		19,199		18,848
Total liabilities		115,705		120,446
Total shareholders' equity		66,036		65,278
Total liabilities and shareholders’ equity		$ 181,741		$ 185,724

[1] Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2018, 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. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] (1) Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information.