Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale) (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	$ (125,000,000)	$ (22,000,000)
Unrealized loss position less than 12 months - fair value	13,060,000,000	5,223,000,000
Unrealized loss position 12 months or more - unrealized loss	(142,000,000)	(186,000,000)
Unrealized loss position 12 months or more - fair value	3,997,000,000	5,518,000,000
Total unrealized loss	(267,000,000)	(208,000,000)
Total fair value	17,057,000,000	10,741,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(125,000,000)	(22,000,000)
Unrealized loss position less than 12 months - fair value	13,060,000,000	5,223,000,000
Unrealized loss position 12 months or more - unrealized loss	(141,000,000)	(185,000,000)
Unrealized loss position 12 months or more - fair value	3,936,000,000	5,503,000,000
Total unrealized loss	(266,000,000)	(207,000,000)
Total fair value	16,996,000,000	10,726,000,000
US Treasury and Government Agencies Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(2,000,000)	(1,000,000)
Unrealized loss position less than 12 months - fair value	1,167,000,000	1,426,000,000
Total unrealized loss	(2,000,000)	(1,000,000)
Total fair value	1,167,000,000	1,426,000,000
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(94,000,000)	(4,000,000)
Unrealized loss position less than 12 months - fair value	7,736,000,000	644,000,000
Unrealized loss position 12 months or more - unrealized loss	(24,000,000)	(37,000,000)
Unrealized loss position 12 months or more - fair value	1,259,000,000	1,963,000,000
Total unrealized loss	(118,000,000)	(41,000,000)
Total fair value	8,995,000,000	2,607,000,000
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(5,000,000)	(5,000,000)
Unrealized loss position less than 12 months - fair value	443,000,000	276,000,000
Unrealized loss position 12 months or more - unrealized loss	(84,000,000)	(94,000,000)
Unrealized loss position 12 months or more - fair value	1,395,000,000	1,487,000,000
Total unrealized loss	(89,000,000)	(99,000,000)
Total fair value	1,838,000,000	1,763,000,000
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(2,000,000)	(2,000,000)
Unrealized loss position less than 12 months - fair value	429,000,000	681,000,000
Unrealized loss position 12 months or more - unrealized loss	(5,000,000)	(12,000,000)
Unrealized loss position 12 months or more - fair value	150,000,000	322,000,000
Total unrealized loss	(7,000,000)	(14,000,000)
Total fair value	579,000,000	1,003,000,000
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(5,000,000)	(4,000,000)
Unrealized loss position less than 12 months - fair value	1,504,000,000	928,000,000
Unrealized loss position 12 months or more - unrealized loss	(3,000,000)	(7,000,000)
Unrealized loss position 12 months or more - fair value	339,000,000	335,000,000
Total unrealized loss	(8,000,000)	(11,000,000)
Total fair value	1,843,000,000	1,263,000,000
Asset backed [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(5,000,000)	(4,000,000)
Unrealized loss position less than 12 months - fair value	946,000,000	913,000,000
Unrealized loss position 12 months or more - unrealized loss	(19,000,000)	(28,000,000)
Unrealized loss position 12 months or more - fair value	605,000,000	1,133,000,000
Total unrealized loss	(24,000,000)	(32,000,000)
Total fair value	1,551,000,000	2,046,000,000
State and Municipal [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(8,000,000)	(500,000)
Unrealized loss position less than 12 months - fair value	503,000,000	41,000,000
Unrealized loss position 12 months or more - unrealized loss	(3,000,000)	(3,000,000)
Unrealized loss position 12 months or more - fair value	49,000,000	77,000,000
Total unrealized loss	(11,000,000)	(3,000,000)
Total fair value	552,000,000	118,000,000
Other Debt Securities [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(4,000,000)	(2,000,000)
Unrealized loss position less than 12 months - fair value	332,000,000	314,000,000
Unrealized loss position 12 months or more - unrealized loss	(3,000,000)	(4,000,000)
Unrealized loss position 12 months or more - fair value	139,000,000	186,000,000
Total unrealized loss	(7,000,000)	(6,000,000)
Total fair value	471,000,000	500,000,000
Corporate Stocks And Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position 12 months or more - unrealized loss	(1,000,000)	(1,000,000)
Unrealized loss position 12 months or more - fair value	61,000,000	15,000,000
Total unrealized loss	(1,000,000)	(1,000,000)
Total fair value	$ 61,000,000	$ 15,000,000