Investment Securities (Contractual Maturity of Debt Securities) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, Total	$ 43,425	$ 47,988
Available-for-sale Securities, Fair value, Total	44,519	48,607
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	218
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	3,766
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	6,831
Available for Sale Securities, Amortized Cost, After 10 years	32,255
Available for Sale Securities, Amortized Cost, Total	43,070	47,554
Available-for-sale Securities, Fair value, 1 year or less	219
Available-for-sale Securities, Fair value, After 1 year through 5 years	3,875
Available-for-sale Securities, Fair value, After 5 years through 10 years	6,949
Available-for-sale Securities, Fair value, After 10 years	33,114
Available-for-sale Securities, Fair value, Total	44,157	48,174
Held to Maturity Securities, Amortized Cost, 1 year or less	20
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	1,063
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	1,423
Held to Maturity Securities, Amortized Cost, After 10 years	9,577
Held to Maturity Securities, Amortized Cost, Total	12,083
Held-to-maturity Securities, Fair Value, 1 year or less	21
Held-to-maturity Securities, Fair Value, After 1 year through 5 years	1,113
Held-to-maturity Securities, Fair Value, After 5 years through 10 years	1,478
Held-to-maturity Securities, Fair Value, After 10 years	9,804
Held-to-maturity Securities, Fair Value, Total	12,416
US Treasury and Government Agencies Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	1,317
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	3,422
Available for Sale Securities, Amortized Cost, After 10 years	471
Available for Sale Securities, Amortized Cost, Total	5,210
Held to Maturity Securities, Amortized Cost, After 10 years	243
Held to Maturity Securities, Amortized Cost, Total	243
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	97
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	495
Available for Sale Securities, Amortized Cost, After 10 years	19,098
Available for Sale Securities, Amortized Cost, Total	19,690
Held to Maturity Securities, Amortized Cost, After 10 years	5,712
Held to Maturity Securities, Amortized Cost, Total	5,712
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	1
Available for Sale Securities, Amortized Cost, After 10 years	5,093
Available for Sale Securities, Amortized Cost, Total	5,102
Asset backed [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	826
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	2,088
Available for Sale Securities, Amortized Cost, After 10 years	2,422
Available for Sale Securities, Amortized Cost, Total	5,380
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	283
State and Municipal [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	4
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	118
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	299
Available for Sale Securities, Amortized Cost, After 10 years	1,444
Available for Sale Securities, Amortized Cost, Total	1,865
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	21
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	641
Held to Maturity Securities, Amortized Cost, After 10 years	1,378
Held to Maturity Securities, Amortized Cost, Total	2,060
Other Debt Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	101
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	996
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	455
Available for Sale Securities, Amortized Cost, After 10 years	243
Available for Sale Securities, Amortized Cost, Total	1,795
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	327
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	8
Held to Maturity Securities, Amortized Cost, After 10 years	283
Held to Maturity Securities, Amortized Cost, Total	283
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	69
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	404
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	20
Available for Sale Securities, Amortized Cost, After 10 years	98
Available for Sale Securities, Amortized Cost, Total	591
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	1,032
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	172
Held to Maturity Securities, Amortized Cost, Total	1,204
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	0
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	51
Available for Sale Securities, Amortized Cost, After 10 years	3,386
Available for Sale Securities, Amortized Cost, Total	3,437
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	6
Held to Maturity Securities, Amortized Cost, After 10 years	1,267
Held to Maturity Securities, Amortized Cost, Total	1,273
Asset backed [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	44
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	4
Held to Maturity Securities, Amortized Cost, After 10 years	694
Held to Maturity Securities, Amortized Cost, Total	981
State and Municipal [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Held to Maturity Securities, Amortized Cost, 1 year or less	20
Other Debt Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Held to Maturity Securities, Amortized Cost, Total	327
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, Total	43,070
Available-for-sale Securities, Fair value, Total	44,157
Weighted-average yield, GAAP basis, available for sale securities	2.89%
Held to Maturity Securities, Amortized Cost, Total	12,083
Held-to-maturity Securities, Fair Value, Total	$ 12,416
Weighted-average yield, GAAP basis, held to maturity securities	3.60%
Debt Securities [Member] | One Year or Less [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	3.00%
Weighted-average yield, GAAP basis, held to maturity securities	4.42%
Debt Securities [Member] | After One Year Through Five Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.65%
Weighted-average yield, GAAP basis, held to maturity securities	3.43%
Debt Securities [Member] | After Five Years Through Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	2.35%
Weighted-average yield, GAAP basis, held to maturity securities	3.36%
Debt Securities [Member] | After Ten Years [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted-average yield, GAAP basis, available for sale securities	3.00%
Weighted-average yield, GAAP basis, held to maturity securities	3.65%