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, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Investment And Embedded Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value	$ 482		$ 427
Notional Value/Payment Provision	7,557		12,906
Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value	38		41
Notional Value/Payment Provision	2,598		1,973
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Foreign Exchange Future [Member]
Derivatives, Fair Value [Line Items]
Fair Value	(6)		7
Notional Value/Payment Provision	841		674
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Cross Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	50
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures Contracts On Money Market Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value	3		7
Notional Value/Payment Provision	2,200		10,476
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures contracts on notes and bonds [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0		(4)
Notional Value/Payment Provision	931		1,055
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options On Money Market Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	3,030		292
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Single-Stock Future [Member]
Derivatives, Fair Value [Line Items]
Fair Value	6	[1]	(16)	[1]
Notional Value/Payment Provision	2,342	[1]	1,367	[1]
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options On Equity Market Indices [Member]
Derivatives, Fair Value [Line Items]
Fair Value	32	[1]	54	[1]
Notional Value/Payment Provision	250	[1]	250	[1]
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Credit Default Swap [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0		3
Notional Value/Payment Provision	0		350
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	6		6
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options On Notes and Bonds Futures [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	56		0
Fixed Maturities Available For Sale [Member] | Convertibles and Bonds with Warrants Attached [Member]
Derivatives, Fair Value [Line Items]
Fair Value	410		357
Notional Value/Payment Provision	378		353
Fixed Maturities Available For Sale [Member] | Dollar Rolls [Member]
Derivatives, Fair Value [Line Items]
Fair Value	75		60
Notional Value/Payment Provision	71		56
Accounts Payable Future Policy Benefits [Member] | Guaranteed Living Benefits [Member]
Derivatives, Fair Value [Line Items]
Fair Value	(1,487)	[2]	(1,505)	[2]
Notional Value/Payment Provision	$ 1,207	[2]	$ 1,378	[2]

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

[2] Includes both future policy benefits reserves and fair value derivative adjustment. Refer to Note 5 for additional information. 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.