Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Cash Flows) (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015		Jan. 14, 2016
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Equity Method Investment, Ownership Percentage	100.00%
Net cash flows from operating activities	$ 3,837		$ 2,699
Payments To Acquire Available For Sale Securities Debt Condensed	(23,837)		(13,060)
Purchases of fixed maturities held to maturity	(189)		(39)
Purchases of equity securities	(100)		(122)
Proceeds From Sale Of Available For Sale Securities Debt Condensed	13,863		5,233
Sales of equity securities	963		150
Maturities and redemptions of fixed maturities available for sale	6,936		5,257
Maturities and redemptions of fixed maturities held to maturity	627		552
Net change in short-term investments	11,866		421
Net derivative instruments settlements	(181)		62
Cash Acquired from Acquisition	71		620
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	(14,248)		259
Payment Of Contributions To Subsidiary	0		0
Other	26		(138)
Net cash flows used for investing activities	(4,274)		(1,425)
Dividends paid on Common Shares	(851)		(644)
Common Shares repurchased	0		(758)
Proceeds from issuance of long-term debt	0		800
Proceeds from issuance of repurchase agreements	1,457		1,478
Repayment of long-term debt	0		(451)
Repayments of repurchase agreements	(1,455)		(1,477)
Proceeds from share-based compensation plans, including windfall tax benefits	117		89
Dividend to Parent Company	0		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	473		351
Policyholder contract withdrawals	(247)		(159)
Other	(4)		(6)
Net cash flows used for financing activities	(510)		(777)
Effect of foreign currency rate changes on cash and cash equivalents	42		(114)
Net increase (decrease) in cash	(905)		383
Cash – beginning of period	1,775	[1],[2]	655	[3]
Cash – end of period	870	[2],[4]	1,038	[3]
Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	(7,372)		(276)
Payments To Acquire Available For Sale Securities Debt Condensed	0		(8)
Purchases of fixed maturities held to maturity	0		0
Purchases of equity securities	0		0
Proceeds From Sale Of Available For Sale Securities Debt Condensed	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
Payment Of Contributions To Subsidiary	4,680		625
Other	0		8
Net cash flows used for investing activities	4,680		625
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		276
Capital contribution	(4,680)		(625)
Advances To From Affiliates Financing Activities	0		0
Net proceeds from (payments to) affiliated notional cash pooling program	(325)	[2]	(606)
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other	0		0
Net cash flows used for financing activities	2,367		(955)
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	(325)		(606)
Cash – beginning of period	(971)	[1],[2]	(555)	[3]
Cash – end of period	(1,296)	[2],[4]	(1,161)	[3]
Chubb Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	3,399		350
Payments To Acquire Available For Sale Securities Debt Condensed	0		0
Purchases of fixed maturities held to maturity	0		0
Purchases of equity securities	0		0
Proceeds From Sale Of Available For Sale Securities Debt Condensed	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
Payment Of Contributions To Subsidiary	(2,330)		0
Other	0		0
Net cash flows used for investing activities	(2,330)		0
Dividends paid on Common Shares	(851)		(644)
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		0
Capital contribution	0
Advances To From Affiliates Financing Activities	(258)		(416)
Net proceeds from (payments to) affiliated notional cash pooling program	45	[2]	727	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other	0		0
Net cash flows used for financing activities	(1,064)		(333)
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	5		17
Cash – beginning of period	1	[1],[2]	0	[3]
Cash – end of period	6	[2],[4]	17	[3]
Chubb INA Holdings Inc (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	3,892		(46)
Payments To Acquire Available For Sale Securities Debt Condensed	(154)
Purchases of fixed maturities held to maturity	0		0
Purchases of equity securities	0		0
Proceeds From Sale Of Available For Sale Securities Debt Condensed	66		0
Sales of equity securities	0		0
Maturities and redemptions of fixed maturities available for sale	59		0
Maturities and redemptions of fixed maturities held to maturity	0		0
Net change in short-term investments	7,627		215
Net derivative instruments settlements	(10)		(10)
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	(14,282)		0
Payment Of Contributions To Subsidiary	(20)		(625)
Other	(3)		(25)
Net cash flows used for investing activities	(6,717)		(445)
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		0
Capital contribution	2,330
Advances To From Affiliates Financing Activities	219		272
Net proceeds from (payments to) affiliated notional cash pooling program	280	[2]	(121)	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other	(4)		(6)
Net cash flows used for financing activities	2,825		495
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	0		4
Cash – beginning of period	2	[1],[2]	1	[3]
Cash – end of period	2	[2],[4]	5	[3]
Other Chubb Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	3,918		2,671
Payments To Acquire Available For Sale Securities Debt Condensed	(23,683)		(13,052)
Purchases of fixed maturities held to maturity	(189)		(39)
Purchases of equity securities	(100)		(122)
Proceeds From Sale Of Available For Sale Securities Debt Condensed	13,797		5,233
Sales of equity securities	963		150
Maturities and redemptions of fixed maturities available for sale	6,877		5,257
Maturities and redemptions of fixed maturities held to maturity	627		552
Net change in short-term investments	4,239		206
Net derivative instruments settlements	(171)		72
Acquisition of subsidiaries (net of cash acquired of $71 and $620)	34		259
Payment Of Contributions To Subsidiary	(2,330)		0
Other	29		(121)
Net cash flows used for investing activities	93		(1,605)
Dividends paid on Common Shares	0		0
Common Shares repurchased			(758)
Proceeds from issuance of long-term debt			0
Proceeds from issuance of repurchase agreements	1,457		1,478
Repayment of long-term debt			(1)
Repayments of repurchase agreements	(1,455)		(1,477)
Proceeds from share-based compensation plans, including windfall tax benefits	117		89
Dividend to Parent Company	(7,372)		(276)
Capital contribution	2,350		625
Advances To From Affiliates Financing Activities	39		144
Net proceeds from (payments to) affiliated notional cash pooling program	0	[2]	0	[3]
Policyholder contract deposits	473		351
Policyholder contract withdrawals	(247)		(159)
Other	0		0
Net cash flows used for financing activities	(4,638)		16
Effect of foreign currency rate changes on cash and cash equivalents	42		(114)
Net increase (decrease) in cash	(585)		968
Cash – beginning of period	2,743	[1],[2]	1,209	[3]
Cash – end of period	$ 2,158	[2],[4]	$ 2,177	[3]
The Chubb Corporation [Member]
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Debt Instrument, Face Amount					$ 3,300

[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 September 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 September 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 September 30, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.