Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Dec. 30, 2012	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Notional Amount	$ 68,607	$ 78,589		$ 81,381
Derivative Assets	394	530		585
Derivative Liabilities	94	109		105
Derivative Instruments, Netting adjustments
Derivative Asset, Netting adjustments	(869)		(1,270)	(1,376)
Derivative Liability, Netting adjustments	(559)		(803)	(905)
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	13,952	19,281		16,860
Derivative assets	332	579		604
Derivative liabilities	37	37		41
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	54,655	59,308		64,521
Derivative assets	1,012	1,384		1,543
Derivative liabilities	972	1,350		1,521
Net Derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	68,607	78,589		81,381
Derivative Assets	475	693		771
Derivative Liabilities	450	584		657
Other Collateral [Member]
Derivatives, Fair Value [Line Items]
Notional Amount
Derivative Assets	(81)	(163)		(186)
Derivative Liabilities	(356)	(475)		(552)
Interest Rate [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	13,762	19,085		16,596
Derivative assets	332	579		604
Derivative liabilities	36	30		31
Interest Rate [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	47,315	51,633		55,391
Derivative assets	799	1,144		1,260
Derivative liabilities	762	1,122		1,252
Foreign Exchange [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	190	196		264
Derivative assets
Derivative liabilities	1	7		10
Foreign Exchange [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	4,479	5,025		5,126
Derivative assets	70	75		81
Derivative liabilities	68	68		73
Energy and Commodity [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,890	1,688		1,749
Derivative assets	137	156		183
Derivative liabilities	131	150		178
Credit [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	971	955		2,242
Derivative assets	6	9		19
Derivative liabilities	11	10		18
Equity [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount		7		13
Derivative assets
Derivative liabilities