Investment Securities (Contractual Maturity of Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Total	$ 50,534	$ 48,609
Available-for-sale Securities, Fair value	52,133	48,568
Weighted-average yield, GAAP basis, available for sale securities	3.30%
Weighted-average yield, GAAP basis, held to maturity securities	3.91%
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	566
After 1 year through 5 years	4,413
After 5 years through 10 years	4,603
After 10 years	40,631
Total	50,213	48,241
Available-for-sale Securities, Fair value	571
Available-for-sale Securities, Fair value	4,557
Available-for-sale Securities, Fair value	4,833
Available-for-sale Securities, Fair value	41,851
Available-for-sale Securities, Fair value	51,812	48,200
1 year or less	40
After 1 year through 5 years	646
After 5 years through 10 years	1,609
After 10 years	8,386
Total	10,681	12,066
Held-to-maturity Securities, Fair Value	41
Held-to-maturity Securities, Fair Value	665
Held-to-maturity Securities, Fair Value	1,722
Held-to-maturity Securities, Fair Value	8,804
Held-to-maturity Securities, Fair Value	11,232	12,450
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total	321	368
Available-for-sale Securities, Fair value	321	368
One Year or Less [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.60%
Weighted-average yield, GAAP basis, held to maturity securities	1.79%
After One Year Through Five Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.47%
Weighted-average yield, GAAP basis, held to maturity securities	3.07%
After Five Years Through Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.73%
Weighted-average yield, GAAP basis, held to maturity securities	3.30%
After Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	3.47%
Weighted-average yield, GAAP basis, held to maturity securities	4.10%
US Treasury and Government Agencies Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	2
After 1 year through 5 years	957
After 5 years through 10 years	1,362
After 10 years	452
Total	2,773
After 10 years	228
Total	228
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
After 1 year through 5 years	13
After 5 years through 10 years	705
After 10 years	26,132
Total	26,850
After 10 years	4,578
Total	4,578
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
After 5 years through 10 years	19
After 10 years	6,292
Total	6,313
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	1
After 1 year through 5 years	563
After 5 years through 10 years	52
Total	616
After 1 year through 5 years	316
After 5 years through 10 years	971
After 10 years	5
Total	1,292
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	2
After 1 year through 5 years	174
After 5 years through 10 years	58
After 10 years	2,854
Total	3,088
1 year or less	8
After 1 year through 5 years	53
After 10 years	2,723
Total	2,784
Asset backed [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
After 1 year through 5 years	1,228
After 5 years through 10 years	1,452
After 10 years	2,908
Total	5,588
After 1 year through 5 years	251
After 5 years through 10 years	73
After 10 years	448
Total	772
State and Municipal [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	22
After 1 year through 5 years	50
After 5 years through 10 years	318
After 10 years	1,580
Total	1,970
1 year or less	32
After 1 year through 5 years	25
After 5 years through 10 years	210
After 10 years	404
Total	671
Other Debt Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
1 year or less	539
After 1 year through 5 years	1,426
After 5 years through 10 years	637
After 10 years	413
Total	3,015
After 1 year through 5 years	1
After 5 years through 10 years	355
Total	356
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
After 1 year through 5 years	$ 2