Securities-Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Securities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Gain (Loss) on Investments [Line Items]
Amortized cost	$ 99,020		$ 99,121
Gross unrealized Gains	1,563		1,468
Gross unrealized Losses	1,275		1,837
Fair value	99,308		98,752
Available-for-sale:
Gain (Loss) on Investments [Line Items]
Amortized cost	79,794		79,378
Gross unrealized Gains	1,452		1,406
Gross unrealized Losses	1,030		1,475
Fair value	80,216		79,309
Available-for-sale: | U.S. Treasury
Gain (Loss) on Investments [Line Items]
Amortized cost	13,814		13,363
Gross unrealized Gains	94		94
Gross unrealized Losses	336		605
Fair value	13,572		12,852
Available-for-sale: | U.S. Government agencies
Gain (Loss) on Investments [Line Items]
Amortized cost	446		937
Gross unrealized Gains	7		16
Gross unrealized Losses	4		5
Fair value	449		948
Available-for-sale: | State and political subdivisions
Gain (Loss) on Investments [Line Items]
Amortized cost	6,630		6,706
Gross unrealized Gains	79		60
Gross unrealized Losses	57		92
Fair value	6,652		6,674
Available-for-sale: | Agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	25,277		25,564
Gross unrealized Gains	290		307
Gross unrealized Losses	482		550
Fair value	25,085		25,321
Available-for-sale: | Non-agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	1,097		1,148
Gross unrealized Gains	43		44
Gross unrealized Losses	39		50
Fair value	1,101		1,142
Available-for-sale: | Other RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	2,076		2,299
Gross unrealized Gains	47		43
Gross unrealized Losses	39		57
Fair value	2,084		2,285
Available-for-sale: | Commercial MBS
Gain (Loss) on Investments [Line Items]
Amortized cost	2,144		2,324
Gross unrealized Gains	59		60
Gross unrealized Losses	18		27
Fair value	2,185		2,357
Available-for-sale: | Agency commercial MBS
Gain (Loss) on Investments [Line Items]
Amortized cost	2,078		1,822
Gross unrealized Gains	7		1
Gross unrealized Losses	22		34
Fair value	2,063		1,789
Available-for-sale: | Asset-backed CLOs
Gain (Loss) on Investments [Line Items]
Amortized cost	1,438		1,551
Gross unrealized Gains	11		11
Gross unrealized Losses	0		0
Fair value	1,449		1,562
Available-for-sale: | Other asset-backed securities
Gain (Loss) on Investments [Line Items]
Amortized cost	3,362		2,894
Gross unrealized Gains	8		6
Gross unrealized Losses	6		9
Fair value	3,364		2,891
Available-for-sale: | Foreign covered bonds
Gain (Loss) on Investments [Line Items]
Amortized cost	2,635		2,798
Gross unrealized Gains	81		73
Gross unrealized Losses	0		0
Fair value	2,716		2,871
Available-for-sale: | Corporate bonds
Gain (Loss) on Investments [Line Items]
Amortized cost	1,758		1,808
Gross unrealized Gains	38		32
Gross unrealized Losses	15		25
Fair value	1,781		1,815
Available-for-sale: | Other debt securities
Gain (Loss) on Investments [Line Items]
Amortized cost	14,109		13,077
Gross unrealized Gains	112		91
Gross unrealized Losses	9		18
Fair value	14,212	[1]	13,150	[2]
Available-for-sale: | Equity securities
Gain (Loss) on Investments [Line Items]
Amortized cost	16		18
Gross unrealized Gains	1		1
Gross unrealized Losses	0		0
Fair value	17		19
Available-for-sale: | Money market funds
Gain (Loss) on Investments [Line Items]
Amortized cost	849		938
Gross unrealized Gains	0		0
Gross unrealized Losses	0		0
Fair value	849		938
Available-for-sale: | Non-agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	2,065	[3]	2,131	[4]
Gross unrealized Gains	575	[3]	567	[4]
Gross unrealized Losses	3	[3]	3	[3],[4]
Fair value	2,637	[3]	2,695	[4]
Held-to-maturity:
Gain (Loss) on Investments [Line Items]
Amortized cost	19,226		19,743
Gross unrealized Gains	111		62
Gross unrealized Losses	245		362
Fair value	19,092		19,443
Held-to-maturity: | U.S. Treasury
Gain (Loss) on Investments [Line Items]
Amortized cost	3,325		3,324
Gross unrealized Gains	22		28
Gross unrealized Losses	55		84
Fair value	3,292		3,268
Held-to-maturity: | U.S. Government agencies
Gain (Loss) on Investments [Line Items]
Amortized cost	419		419
Gross unrealized Gains	0		0
Gross unrealized Losses	9		13
Fair value	410		406
Held-to-maturity: | State and political subdivisions
Gain (Loss) on Investments [Line Items]
Amortized cost	40		44
Gross unrealized Gains	1		0
Gross unrealized Losses	0		0
Fair value	41		44
Held-to-maturity: | Agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	14,147		14,568
Gross unrealized Gains	71		20
Gross unrealized Losses	160		236
Fair value	14,058		14,352
Held-to-maturity: | Non-agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	178		186
Gross unrealized Gains	10		10
Gross unrealized Losses	2		3
Fair value	186		193
Held-to-maturity: | Other RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	381		466
Gross unrealized Gains	3		3
Gross unrealized Losses	19		20
Fair value	365		449
Held-to-maturity: | Commercial MBS
Gain (Loss) on Investments [Line Items]
Amortized cost	16		16
Gross unrealized Gains	0		1
Gross unrealized Losses	0		0
Fair value	16		17
Held-to-maturity: | Other securities
Gain (Loss) on Investments [Line Items]
Amortized cost	720		720
Gross unrealized Gains	4		0
Gross unrealized Losses	0		6
Fair value	$ 724		$ 714

[1] Includes $12.2 billion, at fair value, of government-sponsored and guaranteed entities, and sovereign debt.

[2] Includes $11.4 billion, at fair value, of government-sponsored and guaranteed entities, and sovereign debt.

[3] Previously included in the Grantor Trust. The Grantor Trust was dissolved in 2011.

[4] Previously included in the Grantor Trust. The Grantor Trust was dissolved in 2011