Information Provided In Connection With Outstanding Debt Of Subsidiaries (Condensed Consolidating Statement Of Cash Flows) (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017		Jun. 30, 2016
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	$ 1,640		$ 2,153
Purchases of fixed maturities available for sale	(12,260)		(17,077)
Purchases of fixed maturities held to maturity	(212)		(121)
Purchases of equity securities	(82)		(78)
Sales of fixed maturities available for sale	6,873		11,868
Sales of equity securities	104		932
Maturities and redemptions of fixed maturities available for sale	5,169		3,910
Maturities and redemptions of fixed maturities held to maturity	408		443
Net change in short-term investments	354		11,711
Net derivative instruments settlements	(129)		(93)
Acquisition of subsidiaries (net of cash acquired of nil and $71)	0		(14,248)
Capital contribution			0
Other	(121)		81
Net cash flows from (used for) investing activities	104		(2,672)
Dividends paid on Common Shares	(646)		(530)
Common Shares repurchased	(475)		0
Repayment of long-term debt	(500)		0
Proceeds from issuance of repurchase agreements	1,343		904
Repayments of repurchase agreements	(1,338)		(902)
Proceeds from share-based compensation plans	89		92
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	209		274
Policyholder contract withdrawals	(125)		(103)
Other	0		(4)
Net cash flows used for financing activities	(1,443)		(269)
Effect of foreign currency rate changes on cash and cash equivalents	11		24
Net increase (decrease) in cash	312		(764)
Cash – beginning of period	985	[1],[2]	1,775	[3]
Cash – end of period	1,297	[2],[4]	1,011	[3]
Chubb Limited (Parent Guarantor)
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	551		3,213
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 nil and $71)			0
Capital contribution			(2,330)
Other	0		0
Net cash flows from (used for) investing activities	0		(2,330)
Dividends paid on Common Shares	(646)		(530)
Common Shares repurchased	0
Repayment of long-term debt	0
Proceeds from issuance of repurchase agreements	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	264		(247)
Capital contribution			0
Net proceeds from (payments to) affiliated notional cash pooling program	(170)	[2]	(106)	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other			0
Net cash flows used for financing activities	(552)		(883)
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	(1)		0
Cash – beginning of period	1	[1],[2]	1	[3]
Cash – end of period	0	[2],[4]	1	[3]
Chubb INA Holdings Inc (Subsidiary Issuer)
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	1,444		4,050
Purchases of fixed maturities available for sale	(5)		(83)
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	13		0
Maturities and redemptions of fixed maturities held to maturity	0		0
Net change in short-term investments	166		7,829
Net derivative instruments settlements	(7)		(10)
Acquisition of subsidiaries (net of cash acquired of nil and $71)			(14,282)
Capital contribution			0
Other	2		(3)
Net cash flows from (used for) investing activities	169		(6,549)
Dividends paid on Common Shares	0		0
Common Shares repurchased	0
Repayment of long-term debt	(500)
Proceeds from issuance of repurchase agreements	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	(328)		221
Capital contribution			2,330
Net proceeds from (payments to) affiliated notional cash pooling program	(619)	[2]	157	[3]
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other			(4)
Net cash flows used for financing activities	(1,447)		2,704
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	166		205
Cash – beginning of period	1	[1],[2]	2	[3]
Cash – end of period	167	[2],[4]	207	[3]
Other Chubb Limited Subsidiaries
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	1,686		2,262
Purchases of fixed maturities available for sale	(12,255)		(16,994)
Purchases of fixed maturities held to maturity	(212)		(121)
Purchases of equity securities	(82)		(78)
Sales of fixed maturities available for sale	6,873		11,868
Sales of equity securities	104		932
Maturities and redemptions of fixed maturities available for sale	5,156		3,910
Maturities and redemptions of fixed maturities held to maturity	408		443
Net change in short-term investments	188		3,882
Net derivative instruments settlements	(122)		(83)
Acquisition of subsidiaries (net of cash acquired of nil and $71)			34
Capital contribution			(2,330)
Other	(123)		84
Net cash flows from (used for) investing activities	(65)		1,547
Dividends paid on Common Shares	0		0
Common Shares repurchased	(475)
Repayment of long-term debt	0
Proceeds from issuance of repurchase agreements	1,343		904
Repayments of repurchase agreements	(1,338)		(902)
Proceeds from share-based compensation plans	89		92
Dividend to Parent Company	(2,041)		(7,372)
Advances (to) from affiliates	64		26
Capital contribution			2,330
Net proceeds from (payments to) affiliated notional cash pooling program	0	[2]	0	[3]
Policyholder contract deposits	209		274
Policyholder contract withdrawals	(125)		(103)
Other			0
Net cash flows used for financing activities	(2,274)		(4,751)
Effect of foreign currency rate changes on cash and cash equivalents	11		24
Net increase (decrease) in cash	(642)		(918)
Cash – beginning of period	1,965	[1],[2]	2,743	[3]
Cash – end of period	1,323	[2],[4]	1,825	[3]
Consolidation, Eliminations [Member]
Condensed Cash Flow Statements, Captions [Line Items]
Net cash flows from operating activities	(2,041)		(7,372)
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 nil and $71)			0
Capital contribution			4,660
Other	0		0
Net cash flows from (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 issuance of repurchase agreements	0		0
Repayments of repurchase agreements	0		0
Proceeds from share-based compensation plans	0		0
Dividend to Parent Company	2,041		7,372
Advances (to) from affiliates	0		0
Capital contribution			(4,660)
Net proceeds from (payments to) affiliated notional cash pooling program	789	[2]	(51)
Policyholder contract deposits	0		0
Policyholder contract withdrawals	0		0
Other			0
Net cash flows used for financing activities	2,830		2,661
Effect of foreign currency rate changes on cash and cash equivalents	0		0
Net increase (decrease) in cash	789		(51)
Cash – beginning of period	(982)	[1],[2]	(971)	[3]
Cash – end of period	$ (193)	[2],[4]	$ (1,022)	[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 June 30, 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 June 30, 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 June 30, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.