Investment Securities (Summary) (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	$ 46,902,000,000	$ 43,181,000,000
Securities available for sale debt securities, unrealized gains	1,044,000,000	1,262,000,000
Securities available for sale debt securities, unrealized losses	(267,000,000)	(208,000,000)
Securities available for sale, fair value	47,679,000,000	44,235,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	46,474,000,000	42,739,000,000
Securities available for sale debt securities, unrealized gains	1,044,000,000	1,262,000,000
Securities available for sale debt securities, unrealized losses	(266,000,000)	(207,000,000)
Securities available for sale, fair value	47,252,000,000	43,794,000,000
Held to Maturity Securities, Amortized Cost, Total	13,683,000,000	11,588,000,000
Held-to-maturity securities, unrealized gains	309,000,000	414,000,000
Held-to-maturity securities, unrealized losses	(64,000,000)	(18,000,000)
Held-to-maturity securities, fair value	13,928,000,000	11,984,000,000
AFS to HTM Transfer Net Unrealized Gains In AOCI	110,000,000	125,000,000
US Treasury and Government Agencies Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	5,931,000,000	5,237,000,000
Securities available for sale debt securities, unrealized gains	166,000,000	186,000,000
Securities available for sale debt securities, unrealized losses	(2,000,000)	(1,000,000)
Securities available for sale, fair value	6,095,000,000	5,422,000,000
Held to Maturity Securities, Amortized Cost, Total	253,000,000	248,000,000
Held-to-maturity securities, unrealized gains	37,000,000	44,000,000
Held-to-maturity securities, fair value	290,000,000	292,000,000
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	20,629,000,000	17,646,000,000
Securities available for sale debt securities, unrealized gains	331,000,000	438,000,000
Securities available for sale debt securities, unrealized losses	(118,000,000)	(41,000,000)
Securities available for sale, fair value	20,842,000,000	18,043,000,000
Held to Maturity Securities, Amortized Cost, Total	8,199,000,000	5,736,000,000
Held-to-maturity securities, unrealized gains	117,000,000	166,000,000
Held-to-maturity securities, unrealized losses	(58,000,000)	(10,000,000)
Held-to-maturity securities, fair value	8,258,000,000	5,892,000,000
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	4,357,000,000	4,723,000,000
Securities available for sale debt securities, unrealized gains	284,000,000	318,000,000
Securities available for sale debt securities, unrealized losses	(89,000,000)	(99,000,000)
Securities available for sale, fair value	4,552,000,000	4,942,000,000
Held to Maturity Securities, Amortized Cost, Total	252,000,000	270,000,000
Held-to-maturity securities, unrealized gains	7,000,000	13,000,000
Held-to-maturity securities, fair value	259,000,000	283,000,000
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	1,980,000,000	2,178,000,000
Securities available for sale debt securities, unrealized gains	21,000,000	23,000,000
Securities available for sale debt securities, unrealized losses	(7,000,000)	(14,000,000)
Securities available for sale, fair value	1,994,000,000	2,187,000,000
Held to Maturity Securities, Amortized Cost, Total	1,142,000,000	1,200,000,000
Held-to-maturity securities, unrealized gains	48,000,000	53,000,000
Held-to-maturity securities, fair value	1,190,000,000	1,253,000,000
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	4,368,000,000	4,085,000,000
Securities available for sale debt securities, unrealized gains	62,000,000	88,000,000
Securities available for sale debt securities, unrealized losses	(8,000,000)	(11,000,000)
Securities available for sale, fair value	4,422,000,000	4,162,000,000
Held to Maturity Securities, Amortized Cost, Total	812,000,000	1,010,000,000
Held-to-maturity securities, unrealized gains	13,000,000	19,000,000
Held-to-maturity securities, fair value	825,000,000	1,029,000,000
Asset Backed Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	5,377,000,000	5,141,000,000
Securities available for sale debt securities, unrealized gains	82,000,000	78,000,000
Securities available for sale debt securities, unrealized losses	(24,000,000)	(32,000,000)
Securities available for sale, fair value	5,435,000,000	5,187,000,000
Held to Maturity Securities, Amortized Cost, Total	736,000,000	759,000,000
Held-to-maturity securities, unrealized gains	3,000,000	2,000,000
Held-to-maturity securities, unrealized losses	(6,000,000)	(8,000,000)
Held-to-maturity securities, fair value	733,000,000	753,000,000
State and Municipal [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	2,010,000,000	1,953,000,000
Securities available for sale debt securities, unrealized gains	59,000,000	88,000,000
Securities available for sale debt securities, unrealized losses	(11,000,000)	(3,000,000)
Securities available for sale, fair value	2,058,000,000	2,038,000,000
Held to Maturity Securities, Amortized Cost, Total	1,982,000,000	2,042,000,000
Held-to-maturity securities, unrealized gains	78,000,000	111,000,000
Held-to-maturity securities, fair value	2,060,000,000	2,153,000,000
Other Debt Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, amortized cost	1,822,000,000	1,776,000,000
Securities available for sale debt securities, unrealized gains	39,000,000	43,000,000
Securities available for sale debt securities, unrealized losses	(7,000,000)	(6,000,000)
Securities available for sale, fair value	1,854,000,000	1,813,000,000
Held to Maturity Securities, Amortized Cost, Total	307,000,000	323,000,000
Held-to-maturity securities, unrealized gains	6,000,000	6,000,000
Held-to-maturity securities, fair value	313,000,000	329,000,000
Corporate Stocks And Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale equity securities, fair value	427,000,000	441,000,000
Securities available for sale equity securities, unrealized losses	(1,000,000)	(1,000,000)
Securities available for sale equity securities, amortized cost	$ 428,000,000	$ 442,000,000