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, 2019	Dec. 31, 2018
Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		$ 2,752	$ 2,185
Cross-currency swaps
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		0	45
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		2,000	5,250
Options/Futures contracts on notes, bonds, and equities
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		829	1,046
Convertible securities
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	[1]	9	11
To be announced [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		0	6
Total investment and embedded derivative instruments
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		5,590	8,543
Fair Value, Asset		21	43
Futures contracts on equities
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	[2]	560	507
Other
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		207	74
Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision		767	581
Guaranteed Minimum Income Benefit [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	[3]	1,537	1,750
Fair Value, Asset	[3]	0	0
Other Assets [Member] | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Fair Value, Asset		12	15
Other Assets [Member] | Cross-currency swaps
Derivatives, Fair Value [Line Items]
Fair Value, Asset		0	0
Other Assets [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Asset		0	0
Other Assets [Member] | Options/Futures contracts on notes, bonds, and equities
Derivatives, Fair Value [Line Items]
Fair Value, Asset		3	13
Other Assets [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Fair Value, Asset	[2]	0	23
Other Assets [Member] | Other
Derivatives, Fair Value [Line Items]
Fair Value, Asset		15	2
Other Assets [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Asset		15	25
Fixed Maturities [Member] | Convertible securities
Derivatives, Fair Value [Line Items]
Fair Value, Asset	[1]	6	9
Fixed Maturities [Member] | To be announced [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		0	0
Fair Value, Asset		0	6
Equity Securities [Member] | Convertible securities
Derivatives, Fair Value [Line Items]
Fair Value, Liability	[1]	0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(49)	(19)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Cross-currency swaps
Derivatives, Fair Value [Line Items]
Fair Value, Liability		0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(104)	(115)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options/Futures contracts on notes, bonds, and equities
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(11)	(19)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Total investment and embedded derivative instruments
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(164)	(153)
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures contracts on equities
Derivatives, Fair Value [Line Items]
Fair Value, Liability	[2]	(10)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other
Derivatives, Fair Value [Line Items]
Fair Value, Liability		0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability		(10)	0
Balance Sheet Location Accounts Payable Future Policy Benefits [Member] | Guaranteed Minimum Income Benefit [Member]
Derivatives, Fair Value [Line Items]
Fair Value, Liability	[3]	$ (815)	$ (861)

[1] Includes fair value of embedded derivatives.

[2] Related to GMDB and GLB blocks of business.

[3] Includes both future policy benefits reserves and fair value derivative adjustment. Note that the payment provision related to GLB is the net amount at risk. The concept of a notional value does not apply to the GLB reinsurance contracts.