Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions		Mar. 31, 2020		Dec. 31, 2019		Mar. 31, 2019	Dec. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		$ 105,284		$ 109,234
Cash		1,512	[1]	1,537	[2]
Restricted cash		146		109
Insurance and reinsurance balances receivable		10,058		10,357
Reinsurance recoverable on losses and loss expenses		14,898		15,181
Reinsurance recoverable on policy benefits		196		197
Operating Lease, Right-of-Use Asset		509		551
Value of business acquired		289		306
Goodwill and other intangible assets		20,873		21,359
Investments in subsidiaries		0		0
Due from subsidiaries and affiliates, net		0		0
Other assets		19,871		18,663
Total assets		173,127		176,943
Unpaid losses and loss expenses		62,214		62,690		$ 63,143	$ 62,960
Unearned premiums		16,459		16,771
Future policy benefits		5,776		5,814
Due to subsidiaries and affiliates, net		0		0
Affiliated notional cash pooling programs	[1]	0
Operating Lease, Liability		563		603
Repurchase agreements		1,408		1,416
Short-term debt		1,300		1,299
Long-term debt		13,510		13,559
Trust preferred securities		308		308
Other liabilities		19,955		19,755
Total liabilities		120,930		121,612
Total shareholders' equity		52,197		55,331		$ 52,355
Total liabilities and shareholders’ equity		173,127		176,943
Chubb Limited (Parent Guarantor)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		0		0
Cash		10	[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		49,573		50,853
Due from subsidiaries and affiliates, net		3,695		4,776
Other assets		6		12
Total assets		53,284		55,643
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	[1]	740
Repurchase agreements		0		0
Short-term debt		0		0
Long-term debt		0		0
Trust preferred securities		0		0
Other liabilities		347		312
Total liabilities		1,087		312
Total shareholders' equity		52,197		55,331
Total liabilities and shareholders’ equity		53,284		55,643
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		229		1,013
Cash		49	[1]	442	[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		50,731		52,076
Due from subsidiaries and affiliates, net		0		0
Other assets		340		408
Total assets		51,349		53,939
Unpaid losses and loss expenses		0		0
Unearned premiums		0		0
Future policy benefits		0		0
Due to subsidiaries and affiliates, net		3,338		4,446
Affiliated notional cash pooling programs	[1]	0
Repurchase agreements		0		0
Short-term debt		1,299		1,298
Long-term debt		13,510		13,559
Trust preferred securities		308		308
Other liabilities		1,595		1,649
Total liabilities		20,050		21,260
Total shareholders' equity		31,299		32,679
Total liabilities and shareholders’ equity		51,349		53,939
Other Chubb Limited Subsidiaries
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		105,055		108,221
Cash		2,193	[1]	1,093	[2]
Restricted cash		146		109
Insurance and reinsurance balances receivable		12,727		12,920
Reinsurance recoverable on losses and loss expenses		24,293		24,780
Reinsurance recoverable on policy benefits		288		292
Value of business acquired		289		306
Goodwill and other intangible assets		20,873		21,359
Investments in subsidiaries		0		0
Due from subsidiaries and affiliates, net		0		0
Other assets		21,345		20,072
Total assets		187,209		189,152
Unpaid losses and loss expenses		71,283		71,916
Unearned premiums		17,652		17,978
Future policy benefits		5,868		5,909
Due to subsidiaries and affiliates, net		357		330
Affiliated notional cash pooling programs	[1]	0
Repurchase agreements		1,408		1,416
Short-term debt		1		1
Long-term debt		0		0
Trust preferred securities		0		0
Other liabilities		21,635		21,352
Total liabilities		118,204		118,902
Total shareholders' equity		69,005		70,250
Total liabilities and shareholders’ equity		187,209		189,152
Consolidating Adjustments and Eliminations
Condensed Balance Sheet Statements, Captions [Line Items]
Investments		0		0
Cash		(740)	[1]	0	[2]
Restricted cash		0		0
Insurance and reinsurance balances receivable		(2,669)		(2,563)
Reinsurance recoverable on losses and loss expenses		(9,395)		(9,599)
Reinsurance recoverable on policy benefits		(92)		(95)
Value of business acquired		0		0
Goodwill and other intangible assets		0		0
Investments in subsidiaries		(100,304)		(102,929)
Due from subsidiaries and affiliates, net		(3,695)		(4,776)
Other assets		(1,820)		(1,829)
Total assets		(118,715)		(121,791)
Unpaid losses and loss expenses		(9,069)		(9,226)
Unearned premiums		(1,193)		(1,207)
Future policy benefits		(92)		(95)
Due to subsidiaries and affiliates, net		(3,695)		(4,776)
Affiliated notional cash pooling programs	[1]	(740)
Repurchase agreements		0		0
Short-term debt		0		0
Long-term debt		0		0
Trust preferred securities		0		0
Other liabilities		(3,622)		(3,558)
Total liabilities		(18,411)		(18,862)
Total shareholders' equity		(100,304)		(102,929)
Total liabilities and shareholders’ equity		$ (118,715)		$ (121,791)

[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, 2020, 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 the 2019 Form 10-K for additional information.