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	Dec. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	$ 6,287	$ 0
Foreign Exchange Future [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	1,202	0
Cross Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	50	0
Futures Contracts On Money Market Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	3,910	0
Futures contracts on notes and bonds [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	871	0
Convertibles and Bonds with Warrants Attached [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	254	0
Single-Stock Future [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	1,692	0
Options On Equity Market Indices [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	250	0
Other
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	8	0
Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	1,950	0
Guaranteed Living Benefits [Member]
Derivatives, Fair Value [Line Items]
Notional Value/Payment Provision	277	0
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair Value	321	0
Other Assets [Member] | Foreign Exchange Future [Member]
Derivatives, Fair Value [Line Items]
Fair Value	3	0
Other Assets [Member] | Cross Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Other Assets [Member] | Futures Contracts On Money Market Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value	3	0
Other Assets [Member] | Futures contracts on notes and bonds [Member]
Derivatives, Fair Value [Line Items]
Fair Value	13	0
Other Assets [Member] | Single-Stock Future [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Other Assets [Member] | Options On Equity Market Indices [Member]
Derivatives, Fair Value [Line Items]
Fair Value	6	0
Other Assets [Member] | Other
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Other Assets [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value	6	0
Other Assets [Member] | Guaranteed Living Benefits [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair Value	(6)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Foreign Exchange Future [Member]
Derivatives, Fair Value [Line Items]
Fair Value	(4)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Cross Currency Swap [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures Contracts On Money Market Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Futures contracts on notes and bonds [Member]
Derivatives, Fair Value [Line Items]
Fair Value	(2)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Convertibles and Bonds with Warrants Attached [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Single-Stock Future [Member]
Derivatives, Fair Value [Line Items]
Fair Value	(60)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Options On Equity Market Indices [Member]
Derivatives, Fair Value [Line Items]
Fair Value	0	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other
Derivatives, Fair Value [Line Items]
Fair Value	(2)	0
Accounts Payable, Accrued Expenses, And Other Liabilities [Member] | Other Derivative Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair Value	(62)	0
Fixed Maturities Available For Sale [Member] | Convertibles and Bonds with Warrants Attached [Member]
Derivatives, Fair Value [Line Items]
Fair Value	302	0
Accounts Payable Future Policy Benefits [Member] | Guaranteed Living Benefits [Member]
Derivatives, Fair Value [Line Items]
Fair Value	$ (427)	$ 0