Derivatives and Hedging Activities (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivatives Credit Risk Gain Loss Quantitative Disclosure [Abstract]
Net Gains (Losses), Including Hedges, Attributable to the Impact of Changes in Credit Exposure and Credit Spreads on Derivative Contracts	$ (735,000,000)	$ 573,000,000	$ 68,000,000
Interest Rate Contract Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance	(371,000,000)	194,000,000
Net Realized Gains / (Losses)	(60,000,000)	(38,000,000)
Net Unrealized Gains / (Losses) Relating to Instruments Still Held at period-end	19,000,000	(305,000,000)
Purchases	7,000,000	23,000,000
Sales	(28,000,000)	(29,000,000)
Settlements	71,000,000	84,000,000
Transfers Into Level 3	68,000,000
Transfers Out Of Level 3	(61,000,000)
Net transfers in and/or (out) of level 3		(300,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance	(355,000,000)	(371,000,000)
Credit Risk Contract Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance	6,300,000,000	7,040,000,000
Net Realized Gains / (Losses)	246,000,000	46,000,000
Net Unrealized Gains / (Losses) Relating to Instruments Still Held at period-end	(701,000,000)	2,525,000,000
Purchases	138,000,000	348,000,000
Sales	(270,000,000)	(1,310,000,000)
Settlements	(1,597,000,000)	(1,713,000,000)
Transfers Into Level 3	2,503,000,000
Transfers Out Of Level 3	(391,000,000)
Net transfers in and/or (out) of level 3		(636,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance	6,228,000,000	6,300,000,000
Foreign Exchange Contract Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance	842,000,000	1,098,000,000
Net Realized Gains / (Losses)	(17,000,000)	(26,000,000)
Net Unrealized Gains / (Losses) Relating to Instruments Still Held at period-end	(502,000,000)	(351,000,000)
Purchases	17,000,000	29,000,000
Sales	(5,000,000)	(25,000,000)
Settlements	(144,000,000)	(54,000,000)
Transfers Into Level 3	65,000,000
Transfers Out Of Level 3	(221,000,000)
Net transfers in and/or (out) of level 3		171,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance	35,000,000	842,000,000
Commodity Contract Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance	(605,000,000)	220,000,000
Net Realized Gains / (Losses)	(11,000,000)	(35,000,000)
Net Unrealized Gains / (Losses) Relating to Instruments Still Held at period-end	228,000,000	259,000,000
Purchases	63,000,000	125,000,000
Sales	(410,000,000)	(835,000,000)
Settlements	307,000,000	150,000,000
Transfers Into Level 3	(41,000,000)
Transfers Out Of Level 3	165,000,000
Net transfers in and/or (out) of level 3		(489,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance	(304,000,000)	(605,000,000)
Equities Contract Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance	(432,000,000)	(990,000,000)
Net Realized Gains / (Losses)	(80,000,000)	184,000,000
Net Unrealized Gains / (Losses) Relating to Instruments Still Held at period-end	(276,000,000)	151,000,000
Purchases	123,000,000	382,000,000
Sales	(724,000,000)	(683,000,000)
Settlements	267,000,000	159,000,000
Transfers Into Level 3	(50,000,000)
Transfers Out Of Level 3	(76,000,000)
Net transfers in and/or (out) of level 3		365,000,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance	(1,248,000,000)	(432,000,000)
Derivatives Net [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Beginning Balance	5,734,000,000	7,562,000,000
Net Realized Gains / (Losses)	78,000,000	131,000,000
Net Unrealized Gains / (Losses) Relating to Instruments Still Held at period-end	(1,232,000,000)	2,279,000,000
Purchases	348,000,000	907,000,000
Sales	(1,437,000,000)	(2,882,000,000)
Settlements	(1,096,000,000)	(1,374,000,000)
Transfers Into Level 3	2,545,000,000
Transfers Out Of Level 3	(584,000,000)
Net transfers in and/or (out) of level 3		(889,000,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Derivative Contracts Net Value, Ending Balance	4,356,000,000	5,734,000,000
Derivatives Credit Risk Gain Loss Quantitative Disclosure [Abstract]
Net Unrealized Gains / (Losses) Relating to Instruments Still Held at year-end	$ 1,230,000,000	$ 2,280,000,000