Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions		Mar. 31, 2019		Dec. 31, 2018		Mar. 31, 2018	Dec. 31, 2017
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		$ 103,260		$ 100,968
Cash		1,271	[1]	1,247	[2]
Restricted cash	[1]	122		93
Insurance and reinsurance balances receivable		9,826		10,075
Reinsurance recoverable on losses and loss expenses		16,137		15,993
Reinsurance recoverable on policy benefits		203		202
Value of business acquired		289		295
Goodwill and other intangible assets		21,419		21,414
Investments in subsidiaries		0		0
Due from subsidiaries and affiliates, net		0		0
Other assets		18,820		17,484
Total assets		171,347		167,771
Unpaid losses and loss expenses		63,143		62,960		$ 63,139	$ 63,179
Unearned premiums		15,909		15,532
Future policy benefits		5,552		5,506
Due to subsidiaries and affiliates, net		0		0
Affiliated notional cash pooling programs		0		0
Repurchase agreements		1,419		1,418
Short-term debt		509		509
Long-term debt		12,071		12,087
Trust preferred securities		308		308
Other liabilities		20,081		19,139
Total liabilities		118,992		117,459
Total shareholders' equity		52,355		50,312		$ 51,287
Total liabilities and shareholders’ equity		171,347		167,771
Chubb Limited (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		0		0
Cash		2	[1]	1	[2]
Restricted cash	[1]	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		45,648		43,531
Due from subsidiaries and affiliates, net		7,358		7,074
Other assets		9		3
Total assets		53,017		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		331	[1]	35	[2]
Repurchase agreements		0		0
Short-term debt		0		0
Long-term debt		0		0
Trust preferred securities		0		0
Other liabilities		331		262
Total liabilities		662		297
Total shareholders' equity		52,355		50,312
Total liabilities and shareholders’ equity		53,017		50,609
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		229		214
Cash		71	[1]	2	[2]
Restricted cash	[1]	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		51,996		50,209
Due from subsidiaries and affiliates, net		0		0
Other assets		488		1,007
Total assets		52,784		51,432
Unpaid losses and loss expenses		0		0
Unearned premiums		0		0
Future policy benefits		0		0
Due to subsidiaries and affiliates, net		7,974		7,672
Affiliated notional cash pooling programs		691	[1]	617	[2]
Repurchase agreements		0		0
Short-term debt		500		500
Long-term debt		12,070		12,086
Trust preferred securities		308		308
Other liabilities		1,894		2,545
Total liabilities		23,437		23,728
Total shareholders' equity		29,347		27,704
Total liabilities and shareholders’ equity		52,784		51,432
Other Chubb Limited Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		103,031		100,754
Cash		2,220	[1]	1,896	[2]
Restricted cash	[1]	122		93
Insurance and reinsurance balances receivable		11,491		11,861
Reinsurance recoverable on losses and loss expenses		26,232		26,422
Reinsurance recoverable on policy benefits		306		306
Value of business acquired		289		295
Goodwill and other intangible assets		21,419		21,414
Investments in subsidiaries		0		0
Due from subsidiaries and affiliates, net		616		598
Other assets		20,170		18,102
Total assets		185,896		181,741
Unpaid losses and loss expenses		72,998		72,857
Unearned premiums		17,039		16,611
Future policy benefits		5,655		5,610
Due to subsidiaries and affiliates, net		0		0
Affiliated notional cash pooling programs		0	[1]	0	[2]
Repurchase agreements		1,419		1,418
Short-term debt		9		9
Long-term debt		1		1
Trust preferred securities		0		0
Other liabilities		20,478		19,199
Total liabilities		117,599		115,705
Total shareholders' equity		68,297		66,036
Total liabilities and shareholders’ equity		185,896		181,741
Consolidating Adjustments and Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		0		0
Cash		(1,022)	[1]	(652)	[2]
Restricted cash	[1]	0		0
Insurance and reinsurance balances receivable		(1,665)		(1,786)
Reinsurance recoverable on losses and loss expenses		(10,095)		(10,429)
Reinsurance recoverable on policy benefits		(103)		(104)
Value of business acquired		0		0
Goodwill and other intangible assets		0		0
Investments in subsidiaries		(97,644)		(93,740)
Due from subsidiaries and affiliates, net		(7,974)		(7,672)
Other assets		(1,847)		(1,628)
Total assets		(120,350)		(116,011)
Unpaid losses and loss expenses		(9,855)		(9,897)
Unearned premiums		(1,130)		(1,079)
Future policy benefits		(103)		(104)
Due to subsidiaries and affiliates, net		(7,974)		(7,672)
Affiliated notional cash pooling programs		(1,022)	[1]	(652)	[2]
Repurchase agreements		0		0
Short-term debt		0		0
Long-term debt		0		0
Trust preferred securities		0		0
Other liabilities		(2,622)		(2,867)
Total liabilities		(22,706)		(22,271)
Total shareholders' equity		(97,644)		(93,740)
Total liabilities and shareholders’ equity		$ (120,350)		$ (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 March 31, 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.