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		Mar. 31, 2026	Dec. 31, 2025
Foreign currency forward contracts | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		$ 4,519	$ 4,912
Options/Futures/Forward contracts on notes and bonds | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,508	1,216
Convertible securities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	3	5
Investment And Embedded Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		37	28
Fair Value, Liability		(358)	(242)
Derivative, Notional Amount		6,030	6,133
Futures contracts on equities | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[2]	807	943
Other derivative instruments | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		242	334
Other Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,049	1,277
Currency Swap [Member] | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		265	266
Fair Value, Liability		(80)	232
Derivative, Notional Amount		5,981	5,041
Currency Swap [Member] | Fair Value Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		2,090	2,046
Currency Swap [Member] | Net Investment Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		3,891	2,995
Other Assets [Member] | Foreign currency forward contracts | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		20	18
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		13	4
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]	18	3
Other Assets [Member] | Other derivative instruments | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		10	8
Other Assets [Member] | Other Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		28	11
Other Assets [Member] | Currency Swap [Member] | Fair Value Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		155	198
Other Assets [Member] | Currency Swap [Member] | Net Investment Hedging | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		110	68
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]	4	6
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		(337)	(230)
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		(21)	(12)
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]	0	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		0	(4)
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		0	(4)
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		(2)	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		(78)	(232)
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.