Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Detail) - USD ($)	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Derivatives, Fair Value [Line Items]
Notional Amount	$ 83,370,000,000	$ 65,317,000,000	$ 63,278,000,000
Derivative Assets	680,000,000	454,000,000	342,000,000
Derivative Liabilities	444,000,000	543,000,000	116,000,000
Derivative Asset, Netting adjustments	(945,000,000)	(1,034,000,000)	(613,000,000)
Derivative Liability, Netting adjustments	(566,000,000)	(542,000,000)	(393,000,000)
Derivative Assets	(113,000,000)	(155,000,000)	(71,000,000)
Derivative Liabilities	(232,000,000)	(241,000,000)	(268,000,000)
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	18,229,000,000	15,466,000,000	14,359,000,000
Derivative assets	405,000,000	280,000,000	250,000,000
Derivative liabilities	12,000,000	26,000,000	44,000,000
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	65,141,000,000	49,851,000,000	48,919,000,000
Derivative assets	1,333,000,000	1,363,000,000	776,000,000
Derivative liabilities	1,230,000,000	1,300,000,000	733,000,000
Net Derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	83,370,000,000	65,317,000,000	63,278,000,000
Derivative Assets	793,000,000	609,000,000	413,000,000
Derivative Liabilities	676,000,000	784,000,000	384,000,000
Interest Rate [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	17,910,000,000	15,095,000,000	13,946,000,000
Derivative assets	394,000,000	272,000,000	237,000,000
Derivative liabilities	12,000,000	26,000,000	44,000,000
Interest Rate [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	57,006,000,000	43,771,000,000	42,088,000,000
Derivative assets	725,000,000	665,000,000	608,000,000
Derivative liabilities	644,000,000	618,000,000	572,000,000
Foreign Exchange [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	319,000,000	371,000,000	413,000,000
Derivative assets	11,000,000	8,000,000	13,000,000
Foreign Exchange [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	6,161,000,000	4,024,000,000	4,433,000,000
Derivative assets	119,000,000	85,000,000	69,000,000
Derivative liabilities	112,000,000	81,000,000	64,000,000
Commodity [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,394,000,000	1,544,000,000	1,780,000,000
Derivative assets	482,000,000	608,000,000	95,000,000
Derivative liabilities	469,000,000	594,000,000	90,000,000
Credit [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	580,000,000	512,000,000	618,000,000
Derivative assets	7,000,000	5,000,000	4,000,000
Derivative liabilities	$ 5,000,000	$ 7,000,000	$ 7,000,000