Maturity Distribution by Carrying Amount and Yield (on Tax Equivalent Basis) of Investment Securities Portfolio (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Securities available-for-sale, amount:
One year or less	$ 3,552
Over 1 through 5 years	23,572
Over 5 through 10 years	6,908
Over 10 years	3,973
Total	84,540
Securities held-to-maturity, amount:
One year or less	4
Over 1 through 5 years	559
Over 5 through 10 years	394
Over 10 years	50
Total	8,869
Mortgage-Backed Securities
Securities available-for-sale, amount:
Without single maturity date	43,320
Securities held-to-maturity, amount:
Without single maturity date	7,862
Asset-Backed Securities
Securities available-for-sale, amount:
Without single maturity date	2,269
Equity Securities
Securities available-for-sale, amount:
Without single maturity date	946	[1]
U.S. Treasury
Securities available-for-sale, amount:
One year or less	174
Over 1 through 5 years	9,180
Over 5 through 10 years	1,868
Over 10 years	3,248
Total	14,470
Securities held-to-maturity, amount:
Over 1 through 5 years	559
Over 5 through 10 years	363
Total	922
Securities available-for-sale, yield:
One year or less	0.65%	[2]
Over 1 through 5 years	0.95%	[2]
Over 5 through 10 years	2.91%	[2]
Over 10 years	3.13%	[2]
Total	1.69%	[2]
Securities held-to-maturity, yield:
Over 1 through 5 years	1.82%	[2]
Over 5 through 10 years	2.66%	[2]
Total	2.15%	[2]
U.S. Government Agencies
Securities available-for-sale, amount:
Over 1 through 5 years	1,011
Over 5 through 10 years	86
Total	1,097
Securities available-for-sale, yield:
Over 1 through 5 years	1.62%	[2]
Over 5 through 10 years	2.06%	[2]
Total	1.65%	[2]
State And Political Subdivisions
Securities available-for-sale, amount:
One year or less	110
Over 1 through 5 years	2,397
Over 5 through 10 years	2,548
Over 10 years	547
Total	5,602
Securities held-to-maturity, amount:
One year or less	1
Over 5 through 10 years	31
Over 10 years	50
Total	82
Securities available-for-sale, yield:
One year or less	1.53%	[2]
Over 1 through 5 years	1.58%	[2]
Over 5 through 10 years	3.10%	[2]
Over 10 years	4.15%	[2]
Total	2.52%	[2]
Securities held-to-maturity, yield:
One year or less	6.87%	[2]
Over 5 through 10 years	6.59%	[2]
Over 10 years	6.55%	[2]
Total	6.57%	[2]
Other bonds, Notes and Debentures
Securities available-for-sale, amount:
One year or less	3,268
Over 1 through 5 years	10,984
Over 5 through 10 years	2,406
Over 10 years	178
Total	16,836
Securities held-to-maturity, amount:
One year or less	3
Total	3
Securities available-for-sale, yield:
One year or less	1.09%	[2]
Over 1 through 5 years	1.45%	[2]
Over 5 through 10 years	2.83%	[2]
Over 10 years	2.48%	[2]
Total	1.59%	[2]
Securities held-to-maturity, yield:
One year or less	0.07%	[2]
Total	0.07%	[2]
Mortgage/Asset-Backed and Equity Securities
Securities available-for-sale, amount:
Total	46,535
Securities held-to-maturity, amount:
Total	7,862
Securities available-for-sale, yield:
Total	2.80%	[2]
Securities held-to-maturity, yield:
Total	2.99%	[2]
Mortgage/Asset-Backed and Equity Securities | Mortgage-Backed Securities
Securities available-for-sale, amount:
Without single maturity date	43,320
Securities held-to-maturity, amount:
Without single maturity date	7,862
Securities available-for-sale, yield:
Without single maturity date	2.92%	[2]
Securities held-to-maturity, yield:
Without single maturity date	2.99%	[2]
Mortgage/Asset-Backed and Equity Securities | Asset-Backed Securities
Securities available-for-sale, amount:
Without single maturity date	2,269
Securities available-for-sale, yield:
Without single maturity date	1.72%	[2]
Mortgage/Asset-Backed and Equity Securities | Equity Securities
Securities available-for-sale, amount:
Without single maturity date	$ 946	[1]

[1] Includes money market funds.

[2] Yields are based upon the amortized cost of securities.