Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Assets:
Available for sale securities	$ 22,814	[1]	$ 18,597	[1]
Trading securities	361		343
Residential mortgage loans held for sale	99		92
Fair value, recurring
Assets:
Available for sale securities	22,215	[2]	17,846	[2]
Trading securities	361		343
Residential mortgage loans held for sale	598		890
Residential mortgage loans	99	[3]	92	[3]
Derivative assets	1,565		1,553
Total assets	24,838		20,724
Liabilities:
Derivative liabilities	628		754
Short positions	21		8
Total liabilities	649		762
Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets	878		827
Liabilities:
Derivative liabilities	332		389
Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets	175		276
Liabilities:
Derivative liabilities	142		252
Equity Contract | Fair value, recurring
Assets:
Derivative assets	412		384
Liabilities:
Derivative liabilities	54		48
Commodity Contract | Fair value, recurring
Assets:
Derivative assets	100		66
Liabilities:
Derivative liabilities	100		65
US Treasury and Government | Fair value, recurring
Assets:
Available for sale securities	26		26
Trading securities			1
US Government Agencies Debt Securities | Fair value, recurring
Assets:
Available for sale securities	1,630		1,644
Trading securities	6		4
US States and Political Subdivisions Debt Securities | Fair value, recurring
Assets:
Available for sale securities	194		192
Trading securities	24		13
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises | Fair value, recurring
Assets:
Available for sale securities	14,016		12,284
Trading securities	8		3
Other Debt Securities | Fair value, recurring
Assets:
Available for sale securities	6,218		3,582
Trading securities	13		7
Other Debt And Equity Securities [Member] | Fair value, recurring
Assets:
Available for sale securities	131	[2]	118	[2]
Trading securities	310		315
Fair Value, Inputs, Level 1 | Fair value, recurring
Assets:
Available for sale securities	110	[2],[4]	115	[2],[4]
Trading securities	310	[4]	316	[4]
Derivative assets	13	[4]	31	[4]
Total assets	433	[4]	462	[4]
Liabilities:
Derivative liabilities	40	[4]	10	[4]
Short positions	18	[4]	4	[4]
Total liabilities	58	[4]	14	[4]
Fair Value, Inputs, Level 1 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets			13	[4]
Liabilities:
Derivative liabilities	11	[4]	1	[4]
Fair Value, Inputs, Level 1 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets	13	[4]	18	[4]
Liabilities:
Derivative liabilities	29	[4]	9	[4]
Fair Value, Inputs, Level 1 | US Treasury and Government | Fair value, recurring
Assets:
Available for sale securities	26	[4]	26	[4]
Trading securities			1	[4]
Fair Value, Inputs, Level 1 | Other Debt And Equity Securities [Member] | Fair value, recurring
Assets:
Available for sale securities	84	[2],[4]	89	[2],[4]
Trading securities	310	[4]	315	[4]
Fair Value, Inputs, Level 2 | Fair value, recurring
Assets:
Available for sale securities	22,105	[2],[4]	17,731	[2],[4]
Trading securities	50	[4]	26	[4]
Residential mortgage loans held for sale	598	[4]	890	[4]
Derivative assets	1,123	[4]	1,126	[4]
Total assets	23,876	[4]	19,773	[4]
Liabilities:
Derivative liabilities	532	[4]	692	[4]
Short positions	3	[4]	4	[4]
Total liabilities	535	[4]	696	[4]
Fair Value, Inputs, Level 2 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets	861	[4]	802	[4]
Liabilities:
Derivative liabilities	319	[4]	384	[4]
Fair Value, Inputs, Level 2 | Foreign Exchange Contract | Fair value, recurring
Assets:
Derivative assets	175	[4]	276	[4]
Liabilities:
Derivative liabilities	142	[4]	252	[4]
Fair Value, Inputs, Level 2 | Commodity Contract | Fair value, recurring
Assets:
Derivative assets	87	[4]	48	[4]
Liabilities:
Derivative liabilities	71	[4]	56	[4]
Fair Value, Inputs, Level 2 | US Government Agencies Debt Securities | Fair value, recurring
Assets:
Available for sale securities	1,630	[4]	1,644	[4]
Trading securities	6	[4]	4	[4]
Fair Value, Inputs, Level 2 | US States and Political Subdivisions Debt Securities | Fair value, recurring
Assets:
Available for sale securities	194	[4]	192	[4]
Trading securities	23	[4]	12	[4]
Fair Value, Inputs, Level 2 | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises | Fair value, recurring
Assets:
Available for sale securities	14,016	[4]	12,284	[4]
Trading securities	8	[4]	3	[4]
Fair Value, Inputs, Level 2 | Other Debt Securities | Fair value, recurring
Assets:
Available for sale securities	6,218	[4]	3,582	[4]
Trading securities	13	[4]	7	[4]
Fair Value, Inputs, Level 2 | Other Debt And Equity Securities [Member] | Fair value, recurring
Assets:
Available for sale securities	47	[2],[4]	29	[2],[4]
Fair Value, Inputs, Level 3 | Fair value, recurring
Assets:
Trading securities	1		1
Residential mortgage loans	99	[3]	92	[3]
Derivative assets	429		396
Total assets	529		489
Liabilities:
Derivative liabilities	56		52
Total liabilities	56		52
Fair Value, Inputs, Level 3 | Interest Rate Contract | Fair value, recurring
Assets:
Derivative assets	17		12
Liabilities:
Derivative liabilities	2		4
Fair Value, Inputs, Level 3 | Equity Contract | Fair value, recurring
Assets:
Derivative assets	412		384
Liabilities:
Derivative liabilities	54		48
Fair Value, Inputs, Level 3 | US States and Political Subdivisions Debt Securities | Fair value, recurring
Assets:
Trading securities	$ 1		$ 1

[1] Amortized cost of $22,184 and $18,409 at June 30, 2014 and December 31, 2013, respectively.

[2] Excludes FHLB and FRB restricted stock totaling $249 and $350, respectively, at June 30, 2014 and $402 and $349, respectively, at December 31, 2013.

[3] Includes residential mortgage loans originated as held for sale and subsequently transferred to held for investment.

[4] During the three and six months ended June 30, 2014 and for the year ended December 31, 2013, no assets or liabilities were transferred between Level 1 and Level 2.