Investment Securities (Details 8) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012 Y	Dec. 31, 2011
Available-for-sale securities
Available-for-sale securities, total, amortized cost	$ 38,499	$ 51,356
Available-for-sale securities, total, fair value	39,313
Available-for-sale securities, total, weighted average maturity in years	4.5
Available-for-sale securities, total, weighted average yield	3.29%
Held-to-maturity
Held-to-maturity securities, total, amortized cost	34,635	18,877
Held-to-maturity securities, total, fair value	35,081	19,216
Held-to-maturity securities, total, weighted average maturity in years	3.4
Held-to-maturity securities, total, weighted average yield	2.16%
Investment securities
Total investment securities amortized cost	73,134	70,233
Total investment securities, percentage	100.00%	100.00%
U.S. Treasury and agencies [Member]
Held-to-maturity
Held-to-maturity securities, maturities within one year, amortized cost	50
Held-to-maturity securities, maturities after one year through five years, amortized cost	2,448
Held-to-maturity securities, maturities after ten years, amortized cost	60
Held-to-maturity securities, total, amortized cost	2,558	2,560
Held-to-maturity securities, maturities within one year, fair value	50
Held to maturity securities, maturities after one year through five years, fair value	2,475
Held-to-maturity securities, maturities after ten years, fair value	60
Held-to-maturity securities, total, fair value	2,585
Held-to-maturity securities, maturing in one year or less, weighted average maturity years	0.6
Held-to-maturity securities, maturing after one year through five years, weighted average maturity in years	1.7
Held-to-maturity securities, maturing after ten years, weighted average maturity in years	12.7
Held-to-maturity securities, total, weighted average maturity in years	1.9
Held-to-maturity securities, maturing in one year or less, weighted average yield	0.61%
Held-to-maturity securities, maturing after one year through five years, weighted average yield	1.00%
Held-to-maturity securities, maturing after ten years, weighted average yield	1.97%
Held-to-maturity securities, total, weighted average yield	1.01%
Investment securities
Total investment securities amortized cost	3,344	3,605
Total investment securities, percentage	4.60%	5.10%
Mortgage-Backed Securities [Member]
Held-to-maturity
Held-to-maturity securities, maturities within one year, amortized cost	170
Held-to-maturity securities, maturities after one year through five years, amortized cost	30,208
Held-to-maturity securities, maturities after five years through ten years, amortized cost	1,304
Held-to-maturity securities, maturities after ten years, amortized cost	196
Held-to-maturity securities, total, amortized cost	31,878
Held-to-maturity securities, maturities within one year, fair value	170
Held to maturity securities, maturities after one year through five years, fair value	30,616
Held-to-maturity securities, maturities after five year through ten years, fair value	1,322
Held-to-maturity securities, maturities after ten years, fair value	200
Held-to-maturity securities, total, fair value	32,308
Held-to-maturity securities, maturing in one year or less, weighted average maturity years	0.5
Held-to-maturity securities, maturing after one year through five years, weighted average maturity in years	3.4
Held to maturity securities, maturing after five year through ten years, weighted average maturity in years	6.5
Held-to-maturity securities, maturing after ten years, weighted average maturity in years	11.2
Held-to-maturity securities, total, weighted average maturity in years	3.5
Held-to-maturity securities, maturing in one year or less, weighted average yield	1.61%
Held-to-maturity securities, maturing after one year through five years, weighted average yield	2.31%
Held-to-maturity securities, maturing after five year through ten years, weighted average yield	1.33%
Held-to-maturity securities, maturing after ten years, weighted average yield	1.39%
Held-to-maturity securities, total, weighted average yield	2.26%
Investment securities
Total investment securities amortized cost	61,057	57,561
Total investment securities, percentage	83.50%	82.00%
Asset backed Securities [Member]
Held-to-maturity
Held-to-maturity securities, maturities within one year, amortized cost	11
Held-to-maturity securities, maturities after one year through five years, amortized cost	14
Held-to-maturity securities, maturities after five years through ten years, amortized cost	9
Held-to-maturity securities, maturities after ten years, amortized cost	17
Held-to-maturity securities, total, amortized cost	51
Held-to-maturity securities, maturities within one year, fair value	14
Held to maturity securities, maturities after one year through five years, fair value	12
Held-to-maturity securities, maturities after five year through ten years, fair value	11
Held-to-maturity securities, maturities after ten years, fair value	23
Held-to-maturity securities, total, fair value	60
Held-to-maturity securities, maturing in one year or less, weighted average maturity years	0.7
Held-to-maturity securities, maturing after one year through five years, weighted average maturity in years	3.6
Held to maturity securities, maturing after five year through ten years, weighted average maturity in years	7.0
Held-to-maturity securities, maturing after ten years, weighted average maturity in years	22.4
Held-to-maturity securities, total, weighted average maturity in years	9.9
Held-to-maturity securities, maturing in one year or less, weighted average yield	1.29%
Held-to-maturity securities, maturing after one year through five years, weighted average yield	0.94%
Held-to-maturity securities, maturing after five year through ten years, weighted average yield	0.87%
Held-to-maturity securities, maturing after ten years, weighted average yield	0.95%
Held-to-maturity securities, total, weighted average yield	1.00%
Investment securities
Total investment securities amortized cost	860	949
Total investment securities, percentage	1.20%	1.40%
Obligations of state and political subdivisions [Member]
Held-to-maturity
Held-to-maturity securities, maturities after one year through five years, amortized cost	6
Held-to-maturity securities, maturities after five years through ten years, amortized cost	1
Held-to-maturity securities, maturities after ten years, amortized cost	14
Held-to-maturity securities, total, amortized cost	21	23
Held to maturity securities, maturities after one year through five years, fair value	7
Held-to-maturity securities, maturities after five year through ten years, fair value	2
Held-to-maturity securities, maturities after ten years, fair value	14
Held-to-maturity securities, total, fair value	23
Held-to-maturity securities, maturing in one year or less, weighted average maturity years	0.1
Held-to-maturity securities, maturing after one year through five years, weighted average maturity in years	3.3
Held to maturity securities, maturing after five year through ten years, weighted average maturity in years	8.1
Held-to-maturity securities, maturing after ten years, weighted average maturity in years	14.9
Held-to-maturity securities, total, weighted average maturity in years	10.9
Held-to-maturity securities, maturing in one year or less, weighted average yield	8.33%
Held-to-maturity securities, maturing after one year through five years, weighted average yield	7.21%
Held-to-maturity securities, maturing after five year through ten years, weighted average yield	7.74%
Held-to-maturity securities, maturing after ten years, weighted average yield	5.40%
Held-to-maturity securities, total, weighted average yield	6.10%
Investment securities
Total investment securities amortized cost	6,236	6,417
Total investment securities, percentage	8.50%	9.10%
Other debt securities and obligations of foreign government [Member]
Held-to-maturity
Held-to-maturity securities, maturities within one year, amortized cost	3
Held-to-maturity securities, maturities after one year through five years, amortized cost	95
Held-to-maturity securities, maturities after five years through ten years, amortized cost	29
Held-to-maturity securities, total, amortized cost	127
Held-to-maturity securities, maturities within one year, fair value	2
Held to maturity securities, maturities after one year through five years, fair value	90
Held-to-maturity securities, maturities after five year through ten years, fair value	13
Held-to-maturity securities, total, fair value	105
Held-to-maturity securities, maturing in one year or less, weighted average maturity years	0.5
Held-to-maturity securities, maturing after one year through five years, weighted average maturity in years	3.7
Held to maturity securities, maturing after five year through ten years, weighted average maturity in years	8.3
Held-to-maturity securities, total, weighted average maturity in years	4.7
Held-to-maturity securities, maturing in one year or less, weighted average yield	1.22%
Held-to-maturity securities, maturing after one year through five years, weighted average yield	1.38%
Held-to-maturity securities, maturing after five year through ten years, weighted average yield	1.20%
Held-to-maturity securities, total, weighted average yield	1.33%
Other debt securities and investments [Member]
Investment securities
Total investment securities amortized cost	1,637	1,701
Total investment securities, percentage	2.20%	2.40%
U.S. Treasury and agencies [Member]
Available-for-sale securities
Available-for-sale, securities maturing within one year, amortized cost	117
Available-for-sale, securities maturing after one through five year, amortized cost	518
Available-for-sale, securities maturing after five through ten year, amortized cost	141
Available-for-sale, securities maturing after ten years, amortized cost	10
Available-for-sale securities, total, amortized cost	786	1,045
Available-for-sale, securities maturing within one year, fair value	117
Available-for-sale, securities maturing after one through five year, fair value	523
Available-for-sale, securities maturing after five through ten year, fair value	149
Available-for-sale, securities maturing after ten years, fair value	11
Available-for-sale securities, total, fair value	800
Available-for-sale securities, maturing in one year or less, weighted average maturity in years	0.3
Available-for-sale securities, maturing after one year through five years, weighted average maturity in years	1.5
Available-for-sale securities, maturing after five years through ten years, weighted average maturity in years	7.6
Available-for-sale securities, maturing after ten years, weighted average maturity in years	11.1
Available-for-sale securities, total, weighted average maturity in years	2.6
Available-for-sale securities, maturing in one year or less, weighted average yield	1.71%
Available for sale securities, maturing after one year through five years weighted average yield	0.94%
Available-for-sale securities, maturing after five years through ten years, weighted average yield	3.26%
Available-for-sale securities, maturing after ten years, weighted average yield	2.89%
Available-for-sale securities, total, weighted average yield	1.50%
Mortgage-Backed Securities [Member]
Available-for-sale securities
Available-for-sale, securities maturing within one year, amortized cost	3,177
Available-for-sale, securities maturing after one through five year, amortized cost	20,983
Available-for-sale, securities maturing after five through ten year, amortized cost	4,503
Available-for-sale, securities maturing after ten years, amortized cost	516
Available-for-sale securities, total, amortized cost	29,179
Available-for-sale, securities maturing within one year, fair value	3,180
Available-for-sale, securities maturing after one through five year, fair value	21,713
Available-for-sale, securities maturing after five through ten year, fair value	4,350
Available-for-sale, securities maturing after ten years, fair value	514
Available-for-sale securities, total, fair value	29,757
Available-for-sale securities, maturing in one year or less, weighted average maturity in years	0.7
Available-for-sale securities, maturing after one year through five years, weighted average maturity in years	3.1
Available-for-sale securities, maturing after five years through ten years, weighted average maturity in years	6.6
Available-for-sale securities, maturing after ten years, weighted average maturity in years	12.4
Available-for-sale securities, total, weighted average maturity in years	3.5
Available-for-sale securities, maturing in one year or less, weighted average yield	1.66%
Available for sale securities, maturing after one year through five years weighted average yield	2.69%
Available-for-sale securities, maturing after five years through ten years, weighted average yield	2.42%
Available-for-sale securities, maturing after ten years, weighted average yield	1.87%
Available-for-sale securities, total, weighted average yield	2.53%
Asset backed Securities [Member]
Available-for-sale securities
Available-for-sale, securities maturing within one year, amortized cost	17
Available-for-sale, securities maturing after one through five year, amortized cost	150
Available-for-sale, securities maturing after five through ten year, amortized cost	635
Available-for-sale, securities maturing after ten years, amortized cost	7
Available-for-sale securities, total, amortized cost	809
Available-for-sale, securities maturing within one year, fair value	27
Available-for-sale, securities maturing after one through five year, fair value	166
Available-for-sale, securities maturing after five through ten year, fair value	641
Available-for-sale, securities maturing after ten years, fair value	6
Available-for-sale securities, total, fair value	840
Available-for-sale securities, maturing in one year or less, weighted average maturity in years	0.4
Available-for-sale securities, maturing after one year through five years, weighted average maturity in years	3.1
Available-for-sale securities, maturing after five years through ten years, weighted average maturity in years	7.7
Available-for-sale securities, maturing after ten years, weighted average maturity in years	11.8
Available-for-sale securities, total, weighted average maturity in years	6.8
Available-for-sale securities, maturing in one year or less, weighted average yield	18.86%
Available for sale securities, maturing after one year through five years weighted average yield	12.23%
Available-for-sale securities, maturing after five years through ten years, weighted average yield	3.27%
Available-for-sale securities, maturing after ten years, weighted average yield	10.88%
Available-for-sale securities, total, weighted average yield	5.32%
Obligations of state and political subdivisions [Member]
Available-for-sale securities
Available-for-sale, securities maturing within one year, amortized cost	79
Available-for-sale, securities maturing after one through five year, amortized cost	4,979
Available-for-sale, securities maturing after five through ten year, amortized cost	1,083
Available-for-sale, securities maturing after ten years, amortized cost	74
Available-for-sale securities, total, amortized cost	6,215	6,394
Available-for-sale, securities maturing within one year, fair value	79
Available-for-sale, securities maturing after one through five year, fair value	5,211
Available-for-sale, securities maturing after five through ten year, fair value	1,147
Available-for-sale, securities maturing after ten years, fair value	73
Available-for-sale securities, total, fair value	6,510
Available-for-sale securities, maturing in one year or less, weighted average maturity in years	0.3
Available-for-sale securities, maturing after one year through five years, weighted average maturity in years	3.9
Available-for-sale securities, maturing after five years through ten years, weighted average maturity in years	5.7
Available-for-sale securities, maturing after ten years, weighted average maturity in years	20.7
Available-for-sale securities, total, weighted average maturity in years	4.3
Available-for-sale securities, maturing in one year or less, weighted average yield	2.00%
Available for sale securities, maturing after one year through five years weighted average yield	6.79%
Available-for-sale securities, maturing after five years through ten years, weighted average yield	6.77%
Available-for-sale securities, maturing after ten years, weighted average yield	9.37%
Available-for-sale securities, total, weighted average yield	6.76%
Other debt securities and obligations of foreign government [Member]
Available-for-sale securities
Available-for-sale, securities maturing within one year, amortized cost	31
Available-for-sale, securities maturing after ten years, amortized cost	926
Available-for-sale securities, total, amortized cost	957
Available-for-sale, securities maturing within one year, fair value	31
Available-for-sale, securities maturing after ten years, fair value	806
Available-for-sale securities, total, fair value	837
Available-for-sale securities, maturing in one year or less, weighted average maturity in years	0.2
Available-for-sale securities, maturing after ten years, weighted average maturity in years	25.6
Available-for-sale securities, total, weighted average maturity in years	24.8
Available-for-sale securities, maturing in one year or less, weighted average yield	6.04%
Available-for-sale securities, maturing after ten years, weighted average yield	3.61%
Available-for-sale securities, total, weighted average yield	3.69%
Other investments including perpetual preferred securities [Member]
Available-for-sale securities
Available-for-sale securities, total, amortized cost	553
Available-for-sale securities, total, fair value	$ 569
Available-for-sale securities, total, weighted average maturity in years	20.4
Available-for-sale securities, total, weighted average yield	3.65%