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, 2024	Dec. 31, 2023
Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		$ 3,647	$ 3,662
Options/Futures contracts on notes and bonds
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,746	2,062
Convertible securities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	69	64
Investment And Embedded Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		92	110
Fair Value, Liability		(144)	(136)
Derivative, Notional Amount		5,462	5,788
Futures contracts on equities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[2]	1,162	1,157
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		149	136
Fair Value, Liability		(110)	128
Derivative, Notional Amount		3,267	3,250
Fair Value Hedging
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,642	1,631
Net Investment Hedging
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,625	1,619
Other derivative instruments
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		269	217
Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,431	1,374
Other Assets [Member] | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		23	27
Other Assets [Member] | Options/Futures contracts on notes and bonds
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		5	27
Other Assets [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[2]	0	0
Other Assets [Member] | Fair Value Hedging
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		133	126
Other Assets [Member] | Net Investment Hedging
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		16	10
Other Assets [Member] | Other derivative instruments
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		1	0
Other Assets [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		1	0
Fixed Maturities [Member] | Convertible securities
Derivatives, Fair Value [Line Items]
Derivative Asset, Not Subject to Master Netting Arrangement	[1]	64	56
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(135)	(94)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options/Futures contracts on notes and bonds
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(9)	(42)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Fair Value, Liability	[2]	(22)	(37)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Fair Value Hedging
Derivatives, Fair Value [Line Items]
Fair Value, Liability		0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Net Investment Hedging
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(110)	(128)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other derivative instruments
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(6)	(5)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(28)	(42)
Equity Securities | Convertible securities
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.