Investment Securities (Contractual Maturity of Debt Securities) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, Total	$ 42,639,000,000	$ 47,988,000,000
Available-for-sale Securities, Fair value, Total	43,620,000,000	48,607,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	237,000,000
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	3,749,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	6,510,000,000
Available for Sale Securities, Amortized Cost, After 10 years	31,752,000,000
Available for Sale Securities, Amortized Cost, Total	42,248,000,000	47,554,000,000
Available-for-sale Securities, Fair value, 1 year or less	238,000,000
Available-for-sale Securities, Fair value, After 1 year through 5 years	3,843,000,000
Available-for-sale Securities, Fair value, After 5 years through 10 years	6,628,000,000
Available-for-sale Securities, Fair value, After 10 years	32,514,000,000
Available-for-sale Securities, Fair value, Total	43,223,000,000	48,174,000,000
Held to Maturity Securities, Amortized Cost, 1 year or less	20,000,000
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	1,091,000,000
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	1,624,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	8,684,000,000
Held to Maturity Securities, Amortized Cost, Total	11,419,000,000
Held-to-maturity Securities, Fair Value, 1 year or less	20,000,000
Held-to-maturity Securities, Fair Value, After 1 year through 5 years	1,130,000,000
Held-to-maturity Securities, Fair Value, After 5 years through 10 years	1,679,000,000
Held-to-maturity Securities, Fair Value, After 10 years	8,882,000,000
Held-to-maturity Securities, Fair Value, Total	11,711,000,000
US Treasury and Government Agencies Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	2,000,000
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	1,311,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	3,387,000,000
Available for Sale Securities, Amortized Cost, After 10 years	476,000,000
Available for Sale Securities, Amortized Cost, Total	5,176,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	246,000,000
Held to Maturity Securities, Amortized Cost, Total	246,000,000
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	115,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	455,000,000
Available for Sale Securities, Amortized Cost, After 10 years	17,274,000,000
Available for Sale Securities, Amortized Cost, Total	17,844,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	5,427,000,000
Held to Maturity Securities, Amortized Cost, Total	5,427,000,000
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	7,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	1,000,000
Available for Sale Securities, Amortized Cost, After 10 years	4,896,000,000
Available for Sale Securities, Amortized Cost, Total	4,904,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	276,000,000
Held to Maturity Securities, Amortized Cost, Total	276,000,000
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	121,000,000
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	253,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	20,000,000
Available for Sale Securities, Amortized Cost, After 10 years	1,393,000,000
Available for Sale Securities, Amortized Cost, Total	1,787,000,000
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	1,047,000,000
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	146,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	59,000,000
Held to Maturity Securities, Amortized Cost, Total	1,252,000,000
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 10 years	3,703,000,000
Available for Sale Securities, Amortized Cost, Total	3,703,000,000
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	6,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	1,062,000,000
Held to Maturity Securities, Amortized Cost, Total	1,068,000,000
Asset backed [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, 1 year or less	12,000,000
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	906,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	1,889,000,000
Available for Sale Securities, Amortized Cost, After 10 years	2,257,000,000
Available for Sale Securities, Amortized Cost, Total	5,064,000,000
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	17,000,000
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	414,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	341,000,000
Held to Maturity Securities, Amortized Cost, Total	772,000,000
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	4,000,000
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	116,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	331,000,000
Available for Sale Securities, Amortized Cost, After 10 years	1,527,000,000
Available for Sale Securities, Amortized Cost, Total	1,978,000,000
Held to Maturity Securities, Amortized Cost, 1 year or less	20,000,000
Held to Maturity Securities, Amortized Cost, After 1 year through 5 years	21,000,000
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	739,000,000
Held to Maturity Securities, Amortized Cost, After 10 years	1,273,000,000
Held to Maturity Securities, Amortized Cost, Total	2,053,000,000
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	98,000,000
Available for Sale Securities, Amortized Cost, After 1 year through 5 years	1,041,000,000
Available for Sale Securities, Amortized Cost, After 5 years through 10 years	427,000,000
Available for Sale Securities, Amortized Cost, After 10 years	226,000,000
Available for Sale Securities, Amortized Cost, Total	1,792,000,000
Held to Maturity Securities, Amortized Cost, After 5 years through 10 years	325,000,000
Held to Maturity Securities, Amortized Cost, Total	325,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available for Sale Securities, Amortized Cost, Total	42,248,000,000
Available-for-sale Securities, Fair value, Total	43,223,000,000
Weighted-average yield, GAAP basis, available for sale securities	2.87%
Held to Maturity Securities, Amortized Cost, Total	11,419,000,000
Held-to-maturity Securities, Fair Value, Total	$ 11,711,000,000
Weighted-average yield, GAAP basis, held to maturity securities	3.62%
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	3.33%
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	2.60%
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	2.36%
Weighted-average yield, GAAP basis, held to maturity securities	3.24%
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	3.71%