Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Cash Flows) (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016		Jun. 30, 2015		Jan. 14, 2016
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	$ 2,153		$ 1,891
Purchases of fixed maturities available for sale	(17,077)		(9,210)
Purchases of fixed maturities held to maturity	(121)		(24)
Purchases of equity securities	(78)		(70)
Sales of fixed maturities available for sale	11,868		3,642
Sales of equity securities	932		102
Maturities and redemptions of fixed maturities available for sale	3,910		3,691
Maturities and redemptions of fixed maturities held to maturity	443		470
Net change in short-term investments	11,711		228
Net derivative instruments settlements	(93)		(33)
Cash Acquired from Acquisition	71		620
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	(14,248)		255
Capital contribution	0
Other	81		(71)
Net cash flows used for investing activities	(2,672)		(1,020)
Dividends paid on Common Shares	(530)		(427)
Common Shares repurchased	0		(750)
Proceeds from issuance of long-term debt	0		800
Proceeds from issuance of repurchase agreements	904		1,327
Repayment of long-term debt	0		(450)
Repayments of repurchase agreements	(902)		(1,327)
Proceeds from share-based compensation plans, including windfall tax benefits	92		46
Dividend to Parent Company	0
Capital contribution	0
Advances To From Affiliates Financing Activities	0		0
Net proceeds from (payments to) affiliated notional cash pooling program	0		0
Policyholder contract deposits	274		235
Policyholder contract withdrawals	(103)		(107)
Other	(4)		(6)
Net cash flows (used for) from financing activities	(269)		(659)
Effect of foreign currency rate changes on cash and cash equivalents	24		(77)
Net increase (decrease) in cash	(764)		135
Cash – beginning of period	1,775	[1],[2]	655	[3]
Cash – end of period	1,011	[2],[4]	790	[3]
Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	(7,372)		0
Purchases of fixed maturities available for sale	0		0
Purchases of fixed maturities held to maturity	0		0
Purchases of equity securities	0		0
Sales of fixed maturities available for sale	0		0
Sales of equity securities	0		0
Maturities and redemptions of fixed maturities available for sale	0		0
Maturities and redemptions of fixed maturities held to maturity	0		0
Net change in short-term investments	0		0
Net derivative instruments settlements	0		0
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	0		0
Capital contribution	4,660
Other	0		0
Net cash flows used for investing activities	4,660		0
Dividends paid on Common Shares	0		0
Common Shares repurchased			0
Proceeds from issuance of long-term debt			0
Proceeds from issuance of repurchase agreements	0		0
Repayment of long-term debt			0
Repayments of repurchase agreements	0		0
Proceeds from share-based compensation plans, including windfall tax benefits	0		0
Dividend to Parent Company	7,372
Capital contribution	(4,660)
Advances To From Affiliates Financing Activities	0		0
Net proceeds from (payments to) affiliated notional cash pooling program	(51)	[2]	132	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other	0		0
Net cash flows (used for) from financing activities	2,661		132
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	(51)		132
Cash – beginning of period	(971)	[1],[2]	(555)	[3]
Cash – end of period	(1,022)	[2],[4]	(423)	[3]
Chubb Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	3,213		65
Purchases of fixed maturities available for sale	0		0
Purchases of fixed maturities held to maturity	0		0
Purchases of equity securities	0		0
Sales of fixed maturities available for sale	0		0
Sales of equity securities	0		0
Maturities and redemptions of fixed maturities available for sale	0		0
Maturities and redemptions of fixed maturities held to maturity	0		0
Net change in short-term investments	0		0
Net derivative instruments settlements	0		0
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	0		0
Capital contribution	(2,330)
Other	0		0
Net cash flows used for investing activities	(2,330)		0
Dividends paid on Common Shares	(530)		(427)
Common Shares repurchased			0
Proceeds from issuance of long-term debt			0
Proceeds from issuance of repurchase agreements	0		0
Repayment of long-term debt			0
Repayments of repurchase agreements	0		0
Proceeds from share-based compensation plans, including windfall tax benefits	0		0
Dividend to Parent Company	0
Capital contribution	0
Advances To From Affiliates Financing Activities	(247)		223
Net proceeds from (payments to) affiliated notional cash pooling program	(106)	[2]	140	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other	0		0
Net cash flows (used for) from financing activities	(883)		(64)
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	0		1
Cash – beginning of period	1	[1],[2]	0	[3]
Cash – end of period	1	[2],[4]	1	[3]
Chubb INA Holdings Inc (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	4,050		(35)
Purchases of fixed maturities available for sale	(83)		0
Purchases of fixed maturities held to maturity	0		0
Purchases of equity securities	0		0
Sales of fixed maturities available for sale	0		0
Sales of equity securities	0		0
Maturities and redemptions of fixed maturities available for sale	0		0
Maturities and redemptions of fixed maturities held to maturity	0		0
Net change in short-term investments	7,829		190
Net derivative instruments settlements	(10)		(9)
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	(14,282)		0
Capital contribution	0
Other	(3)		(2)
Net cash flows used for investing activities	(6,549)		179
Dividends paid on Common Shares	0		0
Common Shares repurchased			0
Proceeds from issuance of long-term debt			800
Proceeds from issuance of repurchase agreements	0		0
Repayment of long-term debt			(450)
Repayments of repurchase agreements	0		0
Proceeds from share-based compensation plans, including windfall tax benefits	0		0
Dividend to Parent Company	0
Capital contribution	2,330
Advances To From Affiliates Financing Activities	221		(214)
Net proceeds from (payments to) affiliated notional cash pooling program	157	[2]	(272)	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other	(4)		(6)
Net cash flows (used for) from financing activities	2,704		(142)
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	205		2
Cash – beginning of period	2	[1],[2]	1	[3]
Cash – end of period	207	[2],[4]	3	[3]
Other Chubb Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	2,262		1,861
Purchases of fixed maturities available for sale	(16,994)		(9,210)
Purchases of fixed maturities held to maturity	(121)		(24)
Purchases of equity securities	(78)		(70)
Sales of fixed maturities available for sale	11,868		3,642
Sales of equity securities	932		102
Maturities and redemptions of fixed maturities available for sale	3,910		3,691
Maturities and redemptions of fixed maturities held to maturity	443		470
Net change in short-term investments	3,882		38
Net derivative instruments settlements	(83)		(24)
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	34		255
Capital contribution	(2,330)
Other	84		(69)
Net cash flows used for investing activities	1,547		(1,199)
Dividends paid on Common Shares	0		0
Common Shares repurchased			(750)
Proceeds from issuance of long-term debt			0
Proceeds from issuance of repurchase agreements	904		1,327
Repayment of long-term debt			0
Repayments of repurchase agreements	(902)		(1,327)
Proceeds from share-based compensation plans, including windfall tax benefits	92		46
Dividend to Parent Company	(7,372)
Capital contribution	2,330
Advances To From Affiliates Financing Activities	26		(9)
Net proceeds from (payments to) affiliated notional cash pooling program	0	[2]	0	[3]
Policyholder contract deposits	274		235
Policyholder contract withdrawals	(103)		(107)
Other	0		0
Net cash flows (used for) from financing activities	(4,751)		(585)
Effect of foreign currency rate changes on cash and cash equivalents	24		(77)
Net increase (decrease) in cash	(918)		0
Cash – beginning of period	2,743	[1],[2]	1,209	[3]
Cash – end of period	$ 1,825	[2],[4]	$ 1,209	[3]
The Chubb Corporation [Member]
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Intercompany Loan Agreements					$ 10,000

[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 December 31, 2015, 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, 2016 and December 31, 2015, 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 June 30, 2015 and December 31, 2014, 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, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.