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, 2023	Dec. 31, 2022
Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		$ 3,849	$ 4,134
Options/Futures contracts on notes and bonds
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		2,170	1,511
Convertible securities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[1]	32	37
Investment And Embedded Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		53	112
Fair Value, Liability		(158)	(139)
Derivative, Notional Amount		6,051	5,682
Futures contracts on equities
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	[2]	1,080	939
Other Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		348	0
Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,428	939
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		64	17
Fair Value, Liability		(47)	53
Derivative, Notional Amount		3,250	3,199
Fair Value Hedging
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,625	1,595
Net Investment Hedging
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount		1,625	1,604
Other Assets [Member] | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		24	64
Other Assets [Member] | Options/Futures contracts on notes and bonds
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		3	18
Other Assets [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[2]	0	33
Other Assets [Member] | Other Derivatives [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		10	0
Other Assets [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		10	33
Other Assets [Member] | Fair Value Hedging
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		64	17
Other Assets [Member] | Net Investment Hedging
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		0	0
Fixed Maturities [Member] | Convertible securities
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]	26	30
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(131)	(115)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options/Futures contracts on notes and bonds
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(27)	(24)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Fair Value, Liability	[2]	(32)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other Derivatives [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(4)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(36)	0
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		(47)	(53)
Equity Securities | Convertible securities
Derivatives, Fair Value [Line Items]
Fair Value, Liability	[1]	$ 0	$ 0

[1] Includes fair value of embedded derivatives.

[2] Related to MRB book of business.