Investment Securities (Contractual Maturity of Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Total	$ 50,585	$ 48,609
Available-for-sale Securities, Fair value	51,251	48,568
Weighted-average yield, GAAP basis, available for sale securities	3.33%
Total	10,686	12,066
Held-to-maturity Securities, Fair Value	11,146	12,450
Weighted-average yield, GAAP basis, held to maturity securities	4.00%
One Year or Less [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.86%
Weighted-average yield, GAAP basis, held to maturity securities	2.43%
After One Year Through Five Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.44%
Weighted-average yield, GAAP basis, held to maturity securities	3.21%
After Five Years Through Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.75%
Weighted-average yield, GAAP basis, held to maturity securities	3.33%
After Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	3.51%
Weighted-average yield, GAAP basis, held to maturity securities	4.22%
US Treasury and Government Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	2,642
Total	226
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	26,894
Total	4,154
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	6,573
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	841
Total	1,296
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	2,677
Total	3,005
Asset backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	5,539
Total	975
State and Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	1,982
Total	671
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	3,082
Total	359
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	479
After 1 year through 5 years	4,726
After 5 years through 10 years	4,676
After 10 years	40,349
Total	50,230
Available-for-sale Securities, Fair value	50,896
1 year or less	54
After 1 year through 5 years	713
After 5 years through 10 years	1,678
After 10 years	8,241
Debt Securities [Member] | One Year or Less [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value	485
Held-to-maturity Securities, Fair Value	55
Debt Securities [Member] | After One Year Through Five Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value	4,856
Held-to-maturity Securities, Fair Value	729
Debt Securities [Member] | After Five Years Through Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value	4,888
Held-to-maturity Securities, Fair Value	1,770
Debt Securities [Member] | After Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Fair value	40,667
Held-to-maturity Securities, Fair Value	8,592
Debt Securities [Member] | US Treasury and Government Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	2
After 1 year through 5 years	951
After 5 years through 10 years	1,241
After 10 years	448
After 10 years	226
Debt Securities [Member] | Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
After 1 year through 5 years	29
After 5 years through 10 years	757
After 10 years	26,108
After 10 years	4,154
Debt Securities [Member] | Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
After 5 years through 10 years	23
After 10 years	6,550
Debt Securities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	2
After 1 year through 5 years	684
After 5 years through 10 years	144
After 10 years	11
After 1 year through 5 years	205
After 5 years through 10 years	1,086
After 10 years	5
Debt Securities [Member] | Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	4
After 1 year through 5 years	174
After 5 years through 10 years	49
After 10 years	2,450
1 year or less	16
After 1 year through 5 years	57
After 10 years	2,932
Debt Securities [Member] | Asset backed [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	0
After 1 year through 5 years	1,256
After 5 years through 10 years	1,512
After 10 years	2,771
1 year or less	6
After 1 year through 5 years	424
After 5 years through 10 years	82
After 10 years	463
Debt Securities [Member] | State and Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	24
After 1 year through 5 years	55
After 5 years through 10 years	323
After 10 years	1,580
1 year or less	32
After 1 year through 5 years	25
After 5 years through 10 years	153
After 10 years	461
Debt Securities [Member] | Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	447
After 1 year through 5 years	1,577
After 5 years through 10 years	627
After 10 years	431
After 1 year through 5 years	2
After 5 years through 10 years	$ 357