Derivative Instruments Schedule of Credit Default Swaps where we Sell Protection on Single Name Reference Entities and Fair Values (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivative [Line Items]
Notional value	$ 22,767	$ 23,263
Credit default swaps | Single Name Reference Entities
Derivative [Line Items]
Notional value	39	39
Assets	1	1
Liabilities	0	0
Credit default swaps | Single Name Reference Entities | Investment grade | Matures Less Than One Year
Derivative [Line Items]
Notional value	0	0
Assets	0	0
Liabilities	0	0
Credit default swaps | Single Name Reference Entities | Investment grade | Matures After One Year Through Five Years
Derivative [Line Items]
Notional value	39	39
Assets	1	1
Liabilities	$ 0	$ 0