Securities-Amortized Cost, Gross Unrealized Gains and Losses and Fair Value of Securities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Gain (Loss) on Investments [Line Items]
Amortized cost	$ 114,778		$ 99,121
Gross unrealized Gains	1,732		1,468
Gross unrealized Losses	784		1,837
Fair value	115,726		98,752
AOCI, transfers from AFS to HTM Securities, gross unrealized gains	64		74
AOCI, transfers from AFS to HTM Securities, gross unrealized losses	296		343
Available-for-sale:
Gain (Loss) on Investments [Line Items]
Amortized cost	94,641	[1]	79,378	[2]
Gross unrealized Gains	1,545	[1]	1,406	[2]
Gross unrealized Losses	627	[1],[3]	1,475	[2],[4]
Fair value	95,559	[1]	79,309	[2]
Available-for-sale: | U.S. Treasury
Gain (Loss) on Investments [Line Items]
Amortized cost	21,078		13,363
Gross unrealized Gains	112		94
Gross unrealized Losses	89		605
Fair value	21,101		12,852
Available-for-sale: | U.S. Government agencies
Gain (Loss) on Investments [Line Items]
Amortized cost	360		937
Gross unrealized Gains	4		16
Gross unrealized Losses	3		5
Fair value	361		948
Available-for-sale: | State and political subdivisions
Gain (Loss) on Investments [Line Items]
Amortized cost	5,321		6,706
Gross unrealized Gains	108		60
Gross unrealized Losses	25		92
Fair value	5,404		6,674
Available-for-sale: | Agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	30,286		25,564
Gross unrealized Gains	327		307
Gross unrealized Losses	405		550
Fair value	30,208		25,321
Available-for-sale: | Non-agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	990		1,148
Gross unrealized Gains	41		44
Gross unrealized Losses	26		50
Fair value	1,005		1,142
Available-for-sale: | Other RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	1,851		2,299
Gross unrealized Gains	33		43
Gross unrealized Losses	25		57
Fair value	1,859		2,285
Available-for-sale: | Commercial MBS
Gain (Loss) on Investments [Line Items]
Amortized cost	1,993		2,324
Gross unrealized Gains	43		60
Gross unrealized Losses	12		27
Fair value	2,024		2,357
Available-for-sale: | Agency commercial MBS
Gain (Loss) on Investments [Line Items]
Amortized cost	2,883		1,822
Gross unrealized Gains	18		1
Gross unrealized Losses	14		34
Fair value	2,887		1,789
Available-for-sale: | Asset-backed CLOs
Gain (Loss) on Investments [Line Items]
Amortized cost	1,984		1,551
Gross unrealized Gains	12		11
Gross unrealized Losses	0		0
Fair value	1,996		1,562
Available-for-sale: | Other asset-backed securities
Gain (Loss) on Investments [Line Items]
Amortized cost	3,024		2,894
Gross unrealized Gains	7		6
Gross unrealized Losses	6		9
Fair value	3,025		2,891
Available-for-sale: | Foreign covered bonds
Gain (Loss) on Investments [Line Items]
Amortized cost	2,863		2,798
Gross unrealized Gains	87		73
Gross unrealized Losses	1		0
Fair value	2,949		2,871
Available-for-sale: | Corporate bonds
Gain (Loss) on Investments [Line Items]
Amortized cost	1,636		1,808
Gross unrealized Gains	44		32
Gross unrealized Losses	10		25
Fair value	1,670		1,815
Available-for-sale: | Other debt securities
Gain (Loss) on Investments [Line Items]
Amortized cost	17,571		13,077
Gross unrealized Gains	171		91
Gross unrealized Losses	7		18
Fair value	17,735	[5]	13,150	[6]
Available-for-sale: | Equity securities
Gain (Loss) on Investments [Line Items]
Amortized cost	96		18
Gross unrealized Gains	1		1
Gross unrealized Losses	0		0
Fair value	97		19
Available-for-sale: | Money market funds
Gain (Loss) on Investments [Line Items]
Amortized cost	789		938
Gross unrealized Gains	0		0
Gross unrealized Losses	0		0
Fair value	789		938
Available-for-sale: | Non-agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	1,916	[7]	2,131	[8]
Gross unrealized Gains	537	[7]	567	[8]
Gross unrealized Losses	4	[7]	3	[7],[8]
Fair value	2,449	[7]	2,695	[8]
Held-to-maturity:
Gain (Loss) on Investments [Line Items]
Amortized cost	20,137		19,743
Gross unrealized Gains	187		62
Gross unrealized Losses	157		362
Fair value	20,167		19,443
Held-to-maturity: | U.S. Treasury
Gain (Loss) on Investments [Line Items]
Amortized cost	4,166		3,324
Gross unrealized Gains	27		28
Gross unrealized Losses	44		84
Fair value	4,149		3,268
Held-to-maturity: | U.S. Government agencies
Gain (Loss) on Investments [Line Items]
Amortized cost	344		419
Gross unrealized Gains	0		0
Gross unrealized Losses	6		13
Fair value	338		406
Held-to-maturity: | State and political subdivisions
Gain (Loss) on Investments [Line Items]
Amortized cost	29		44
Gross unrealized Gains	1		0
Gross unrealized Losses	0		0
Fair value	30		44
Held-to-maturity: | Agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	14,127		14,568
Gross unrealized Gains	131		20
Gross unrealized Losses	94		236
Fair value	14,164		14,352
Held-to-maturity: | Non-agency RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	157		186
Gross unrealized Gains	10		10
Gross unrealized Losses	2		3
Fair value	165		193
Held-to-maturity: | Other RMBS
Gain (Loss) on Investments [Line Items]
Amortized cost	337		466
Gross unrealized Gains	4		3
Gross unrealized Losses	11		20
Fair value	330		449
Held-to-maturity: | Commercial MBS
Gain (Loss) on Investments [Line Items]
Amortized cost	14		16
Gross unrealized Gains	0		1
Gross unrealized Losses	0		0
Fair value	14		17
Held-to-maturity: | Other securities
Gain (Loss) on Investments [Line Items]
Amortized cost	963		720
Gross unrealized Gains	14		0
Gross unrealized Losses	0		6
Fair value	$ 977		$ 714

[1] Includes gross unrealized gains of $64 million and gross unrealized losses of $296 million recorded in accumulated other comprehensive income primarily related to Agency RMBS that were transferred from available-for-sale to held-to-maturity in 2013. The unrealized gains and losses will be amortized into net interest revenue over the estimated lives of the securities.

[2] Includes gross unrealized gains of $74 million and gross unrealized losses of $343 million recorded in accumulated other comprehensive income primarily related to Agency RMBS that were transferred from available-for-sale to held-to-maturity in 2013. The unrealized gains and losses will be amortized into net interest revenue over the estimated lives of the securities.

[3] Includes gross unrealized losses for 12 months or more of $296 million recorded in accumulated other comprehensive income primarily related to Agency RMBS that were transferred from available-for-sale to held-to-maturity in 2013. The unrealized gains and losses will be amortized into net interest revenue over the estimated lives of the securities.

[4] Includes gross unrealized losses for 12 months or more of $343 million recorded in accumulated other comprehensive income primarily related to Agency RMBS that were transferred from available-for-sale to held-to-maturity in 2013. The unrealized gains and losses will be amortized into net interest revenue over the estimated lives of the securities.

[5] Includes $15.7 billion, at fair value, of government-sponsored and guaranteed entities, and sovereign debt.

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

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

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