Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Cash Flows) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015		Jan. 14, 2016
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	$ 1,020		$ 1,075
Purchases of fixed maturities available for sale	(8,104)		(4,336)
Purchases of fixed maturities held to maturity	(77)		(21)
Purchases of equity securities	(33)		(39)
Sales of fixed maturities available for sale	6,329		2,002
Sales of equity securities	761		28
Maturities and redemptions of fixed maturities available for sale	1,553		1,481
Maturities and redemptions of fixed maturities held to maturity	249		324
Net change in short-term investments	11,932		(255)
Net derivative instruments settlements	(22)		(51)
Cash Acquired from Acquisition	57		0
Payments to Acquire Businesses, Net of Cash Acquired	(14,262)		0
Capital contribution	0
Other	59		(153)
Net cash flows used for investing activities	(1,615)		(1,020)
Dividends paid on Common Shares	(218)		(214)
Common Shares repurchased	0		(347)
Proceeds from issuance of long-term debt	0		800
Proceeds from issuance of repurchase agreements	853		477
Repayments of Long-term Debt	853
Repayments of Short-term Debt	(853)		(477)
Proceeds from share-based compensation plans, including windfall tax benefits	51		39
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	118		101
Policyholder contract withdrawals	(49)		(40)
Other	(4)		(6)
Net cash flows (used for) from financing activities	(102)		333
Effect of foreign currency rate changes on cash and cash equivalents	13		(95)
Net increase in cash	(684)		293
Cash – beginning of period	1,775	[1],[2]	655	[3]
Cash – end of period	1,091	[2],[4]	948	[3]
Chubb Limited (Parent Guarantor)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	3,272		48
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
Capital contribution	(2,330)
Other	0		0
Net cash flows used for investing activities	(2,330)		0
Dividends paid on Common Shares	(218)		(214)
Common Shares repurchased			0
Proceeds from issuance of repurchase agreements			0
Repayments of Short-term Debt	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	(362)		336
Net proceeds from (payments to) affiliated notional cash pooling program	(361)	[2]	$ (168)	[3]
Policyholder contract deposits	0
Policyholder contract withdrawals	0		$ 0
Other	0		0
Net cash flows (used for) from financing activities	(941)		(46)
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase in cash	1		2
Cash – beginning of period	1	[1],[2]	0	[3]
Cash – end of period	2	[2],[4]	2	[3]
Chubb INA Holdings Inc (Subsidiary Issuer)
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	3,109		4
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	7,788		216
Net derivative instruments settlements	0		0
Payments to Acquire Businesses, Net of Cash Acquired	(14,282)
Capital contribution	0
Other	0		0
Net cash flows used for investing activities	(6,494)		216
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
Repayments of Long-term Debt	0
Repayments of Short-term Debt	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	350		(340)
Net proceeds from (payments to) affiliated notional cash pooling program	710	[2]	$ (309)	[3]
Policyholder contract deposits	0
Policyholder contract withdrawals	0		$ 0
Other	(4)		(6)
Net cash flows (used for) from financing activities	3,386		145
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase in cash	1		365
Cash – beginning of period	2	[1],[2]	1	[3]
Cash – end of period	3	[2],[4]	366	[3]
Other Chubb Limited Subsidiaries
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	1,011		1,023
Purchases of fixed maturities available for sale	(8,104)		(4,336)
Purchases of fixed maturities held to maturity	(77)		(21)
Purchases of equity securities	(33)		(39)
Sales of fixed maturities available for sale	6,329		2,002
Sales of equity securities	761		28
Maturities and redemptions of fixed maturities available for sale	1,553		1,481
Maturities and redemptions of fixed maturities held to maturity	249		324
Net change in short-term investments	4,144		(471)
Net derivative instruments settlements	(22)		(51)
Payments to Acquire Businesses, Net of Cash Acquired	20
Capital contribution	(2,330)
Other	59		(153)
Net cash flows used for investing activities	2,549		(1,236)
Dividends paid on Common Shares	0		0
Common Shares repurchased			(347)
Proceeds from issuance of repurchase agreements			477
Repayments of Long-term Debt	(853)
Repayments of Short-term Debt	(853)		(477)
Proceeds from share-based compensation plans, including windfall tax benefits	51		39
Dividend to Parent Company	(6,372)
Capital contribution	2,330
Advances To From Affiliates Financing Activities	12		4
Net proceeds from (payments to) affiliated notional cash pooling program	0	[2]	0	[3]
Policyholder contract deposits	118		101
Policyholder contract withdrawals	(49)		(40)
Other	0		0
Net cash flows (used for) from financing activities	(3,910)		(243)
Effect of foreign currency rate changes on cash and cash equivalents	13		(95)
Net increase in cash	(337)		(551)
Cash – beginning of period	2,743	[1],[2]	1,209	[3]
Cash – end of period	2,406	[2],[4]	658	[3]
Consolidating Adjustments and Eliminations
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items]
Net cash flows from operating activities	(6,372)		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
Payments to Acquire Businesses, Net of Cash Acquired	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 repurchase agreements			0
Repayments of Short-term Debt	0		0
Proceeds from share-based compensation plans, including windfall tax benefits	0		0
Dividend to Parent Company	6,372
Capital contribution	(4,660)
Advances To From Affiliates Financing Activities	0		0
Net proceeds from (payments to) affiliated notional cash pooling program	(349)	[2]	$ 477	[3]
Policyholder contract deposits	0
Policyholder contract withdrawals	0		$ 0
Other	0		0
Net cash flows (used for) from financing activities	1,363		477
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase in cash	(349)		477
Cash – beginning of period	(971)	[1],[2]	(555)	[3]
Cash – end of period	$ (1,320)	[2],[4]	$ (78)	[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 March 31, 2016 and December 31, 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.

[3] 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, 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 March 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.