Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Cash Flows) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017		Mar. 31, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	$ 1,013		$ 1,020
Purchase of fixed maturities available for sale Securities Debt Condensed	(6,250)		(8,104)
Purchases of fixed maturities held to maturity	(157)		(77)
Purchases of equity securities	(37)		(33)
Sales of fixed maturities available for sale	3,395		6,329
Sales of equity securities	46		761
Maturities and redemptions of fixed maturities available for sale	2,543		1,553
Maturities and redemptions of fixed maturities held to maturity	240		249
Net change in short-term investments	232		11,932
Net derivative instruments settlements	(89)		(22)
Acquisition of subsidiaries (net of cash acquired of nil and $57)	0		(14,262)
Capital contribution			0
Other	17		59
Net cash flows used for investing activities	(60)		(1,615)
Cash Acquired from Acquisition	0		57
Dividends paid on Common Shares	(324)		(218)
Common Shares repurchased	(128)		0
Repayment of long-term debt	(500)		0
Proceeds from (Payments for) in Securities Sold under Agreements to Repurchase	753		853
Repayments of repurchase agreements	(752)		(853)
Proceeds from share-based compensation plans	42		51
Dividend to Parent Company	0		0
Advances (to) from affiliates	0		0
Capital contribution			0
Net proceeds from (payments to) affiliated notional cash pooling program	0		0
Policyholder contract deposits	109		118
Policyholder contract withdrawals	(58)		(49)
Other	0		(4)
Net cash flows used for financing activities	(858)		(102)
Effect of foreign currency rate changes on cash and cash equivalents	(17)		13
Net increase (decrease) in cash	78		(684)
Cash – beginning of period	985	[1],[2]	1,775	[3]
Cash – end of period	1,063	[2],[4]	1,091	[3]
Chubb Limited (Parent Guarantor)
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	584		3,272
Purchase of fixed maturities available for sale Securities Debt Condensed	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 nil and $57)			0
Capital contribution			(2,330)
Other	0		0
Net cash flows used for investing activities	0		(2,330)
Dividends paid on Common Shares	(324)		(218)
Common Shares repurchased	0
Repayment of long-term debt	0
Proceeds from (Payments for) in Securities Sold under Agreements to Repurchase	0		0
Repayments of repurchase agreements	0		0
Proceeds from share-based compensation plans	0		0
Dividend to Parent Company	0		0
Advances (to) from affiliates	108		(362)
Capital contribution			0
Net proceeds from (payments to) affiliated notional cash pooling program	(363)	[2]	(361)	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other			0
Net cash flows used for financing activities	(579)		(941)
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	5		1
Cash – beginning of period	1	[1],[2]	1	[3]
Cash – end of period	6	[2],[4]	2	[3]
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	(156)		3,109
Purchase of fixed maturities available for sale Securities Debt Condensed	(4)		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	7		0
Maturities and redemptions of fixed maturities held to maturity	0		0
Net change in short-term investments	173		7,788
Net derivative instruments settlements	(2)		0
Acquisition of subsidiaries (net of cash acquired of nil and $57)			(14,282)
Capital contribution			0
Other	0		0
Net cash flows used for investing activities	174		(6,494)
Dividends paid on Common Shares	0		0
Common Shares repurchased	0
Repayment of long-term debt	(500)
Proceeds from (Payments for) in Securities Sold under Agreements to Repurchase	0		0
Repayments of repurchase agreements	0		0
Proceeds from share-based compensation plans	0		0
Dividend to Parent Company	0		0
Advances (to) from affiliates	(171)		350
Capital contribution			2,330
Net proceeds from (payments to) affiliated notional cash pooling program	653	[2]	710	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other			(4)
Net cash flows used for financing activities	(18)		3,386
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]	2	[3]
Cash – end of period	1	[2],[4]	3	[3]
Other Chubb Limited Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	1,081		1,011
Purchase of fixed maturities available for sale Securities Debt Condensed	(6,246)		(8,104)
Purchases of fixed maturities held to maturity	(157)		(77)
Purchases of equity securities	(37)		(33)
Sales of fixed maturities available for sale	3,395		6,329
Sales of equity securities	46		761
Maturities and redemptions of fixed maturities available for sale	2,536		1,553
Maturities and redemptions of fixed maturities held to maturity	240		249
Net change in short-term investments	59		4,144
Net derivative instruments settlements	(87)		(22)
Acquisition of subsidiaries (net of cash acquired of nil and $57)			20
Capital contribution			(2,330)
Other	17		59
Net cash flows used for investing activities	(234)		2,549
Dividends paid on Common Shares	0		0
Common Shares repurchased	(128)
Repayment of long-term debt	0
Proceeds from (Payments for) in Securities Sold under Agreements to Repurchase	753		853
Repayments of repurchase agreements	(752)		(853)
Proceeds from share-based compensation plans	42		51
Dividend to Parent Company	(496)		(6,372)
Advances (to) from affiliates	63		12
Capital contribution			2,330
Net proceeds from (payments to) affiliated notional cash pooling program	0	[2]	0	[3]
Policyholder contract deposits	109		118
Policyholder contract withdrawals	(58)		(49)
Other			0
Net cash flows used for financing activities	(467)		(3,910)
Effect of foreign currency rate changes on cash and cash equivalents	(17)		13
Net increase (decrease) in cash	363		(337)
Cash – beginning of period	1,965	[1],[2]	2,743	[3]
Cash – end of period	2,328	[2],[4]	2,406	[3]
Consolidating Adjustments and Eliminations
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	(496)		(6,372)
Purchase of fixed maturities available for sale Securities Debt Condensed	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 nil and $57)			0
Capital contribution			4,660
Other	0		0
Net cash flows used for investing activities	0		4,660
Dividends paid on Common Shares	0		0
Common Shares repurchased	0
Repayment of long-term debt	0
Proceeds from (Payments for) in Securities Sold under Agreements to Repurchase	0		0
Repayments of repurchase agreements	0		0
Proceeds from share-based compensation plans	0		0
Dividend to Parent Company	496		6,372
Advances (to) from affiliates	0		0
Capital contribution			(4,660)
Net proceeds from (payments to) affiliated notional cash pooling program	(290)	[2]	(349)
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other			0
Net cash flows used for financing activities	206		1,363
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	(290)		(349)
Cash – beginning of period	(982)	[1],[2]	(971)	[3]
Cash – end of period	$ (1,272)	[2],[4]	$ (1,320)	[3]

[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, 2016, 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, 2017 and December 31, 2016, 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 March 31, 2016 and December 31, 2015, 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, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.