Commitments, Contingencies, And Guarantees (Balance Sheet Locations, Fair Values In Asset Or (Liability) Position, And Notional Values/Payment Provisions Of Derivative Instruments) (Detail) - USD ($) $ in Millions		Jun. 30, 2025	Dec. 31, 2024
Foreign currency forward contracts | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		$ 4,386	$ 3,959
Options/Futures/Forward contracts on notes and bonds | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		909	449
Convertible securities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	6	12
Investment And Embedded Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		58	53
Fair Value, Liability		(143)	(303)
Derivative, Notional Amount		5,301	4,420
Futures contracts on equities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[2]	986	1,047
Other derivative instruments | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		379	211
Other Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,365	1,258
Currency Swap [Member] | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		257	146
Fair Value, Liability		(223)	116
Derivative, Notional Amount		5,013	4,475
Currency Swap [Member] | Fair Value Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		2,010	1,579
Currency Swap [Member] | Net Investment Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		3,003	2,896
Other Assets [Member] | Foreign currency forward contracts | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		45	41
Other Assets [Member] | Options/Futures/Forward contracts on notes and bonds | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		6	0
Other Assets [Member] | Futures contracts on equities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[2]	0	35
Other Assets [Member] | Other derivative instruments | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		7	0
Other Assets [Member] | Other Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		7	35
Other Assets [Member] | Currency Swap [Member] | Fair Value Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		233	103
Other Assets [Member] | Currency Swap [Member] | Net Investment Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		24	43
Fixed Maturities [Member] | Convertible securities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Not Subject to Master Netting Arrangement	[1]	7	12
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Foreign currency forward contracts | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(136)	(295)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options/Futures/Forward contracts on notes and bonds | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(7)	(8)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures contracts on equities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability	[2]	(31)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other derivative instruments | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(5)	(2)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(36)	(2)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Currency Swap [Member] | Fair Value Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair Value, Liability		0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Currency Swap [Member] | Net Investment Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(223)	(116)
Equity Securities | Convertible securities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Not Subject to Master Netting Arrangement	[1]	$ 0	$ 0

[1] Includes fair value of embedded derivatives.

[2] Related to MRB book of business.