Investment Securities (Gross Unrealized Loss and Fair Value of Securities Available for Sale) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	$ (306,000,000)	$ (22,000,000)
Unrealized loss position less than 12 months - fair value	14,717,000,000	5,223,000,000
Unrealized loss position 12 months or more - unrealized loss	(213,000,000)	(186,000,000)
Unrealized loss position 12 months or more - fair value	2,526,000,000	5,518,000,000
Total unrealized loss	(519,000,000)	(208,000,000)
Total fair value	17,243,000,000	10,741,000,000
Quantifying Misstatement In Current Year Financial Statements Amount	6,200,000,000
US Treasury and Government Agencies Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(7,000,000)	(1,000,000)
Unrealized loss position less than 12 months - fair value	1,066,000,000	1,426,000,000
Total unrealized loss	(7,000,000)	(1,000,000)
Total fair value	1,066,000,000	1,426,000,000
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(198,000,000)	(4,000,000)
Unrealized loss position less than 12 months - fair value	7,519,000,000	644,000,000
Unrealized loss position 12 months or more - unrealized loss	(11,000,000)	(37,000,000)
Unrealized loss position 12 months or more - fair value	287,000,000	1,963,000,000
Total unrealized loss	(209,000,000)	(41,000,000)
Total fair value	7,806,000,000	2,607,000,000
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(18,000,000)	(5,000,000)
Unrealized loss position less than 12 months - fair value	855,000,000	276,000,000
Unrealized loss position 12 months or more - unrealized loss	(142,000,000)	(94,000,000)
Unrealized loss position 12 months or more - fair value	1,719,000,000	1,487,000,000
Total unrealized loss	(160,000,000)	(99,000,000)
Total fair value	2,574,000,000	1,763,000,000
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(13,000,000)	(2,000,000)
Unrealized loss position less than 12 months - fair value	454,000,000	681,000,000
Unrealized loss position 12 months or more - unrealized loss	(1,000,000)	(12,000,000)
Unrealized loss position 12 months or more - fair value	6,000,000	322,000,000
Total unrealized loss	(14,000,000)	(14,000,000)
Total fair value	460,000,000	1,003,000,000
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(18,000,000)	(4,000,000)
Unrealized loss position less than 12 months - fair value	1,315,000,000	928,000,000
Unrealized loss position 12 months or more - unrealized loss	(500,000)	(7,000,000)
Unrealized loss position 12 months or more - fair value	14,000,000	335,000,000
Total unrealized loss	(18,000,000)	(11,000,000)
Total fair value	1,329,000,000	1,263,000,000
Asset backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(11,000,000)	(4,000,000)
Unrealized loss position less than 12 months - fair value	1,752,000,000	913,000,000
Unrealized loss position 12 months or more - unrealized loss	(37,000,000)	(28,000,000)
Unrealized loss position 12 months or more - fair value	202,000,000	1,133,000,000
Total unrealized loss	(48,000,000)	(32,000,000)
Total fair value	1,954,000,000	2,046,000,000
State and Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(23,000,000)	(500,000)
Unrealized loss position less than 12 months - fair value	897,000,000	41,000,000
Unrealized loss position 12 months or more - unrealized loss	(21,000,000)	(3,000,000)
Unrealized loss position 12 months or more - fair value	286,000,000	77,000,000
Total unrealized loss	(44,000,000)	(3,000,000)
Total fair value	1,183,000,000	118,000,000
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(17,000,000)	(2,000,000)
Unrealized loss position less than 12 months - fair value	844,000,000	314,000,000
Unrealized loss position 12 months or more - unrealized loss	(1,000,000)	(4,000,000)
Unrealized loss position 12 months or more - fair value	12,000,000	186,000,000
Total unrealized loss	(18,000,000)	(6,000,000)
Total fair value	856,000,000	500,000,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(305,000,000)	(22,000,000)
Unrealized loss position less than 12 months - fair value	14,702,000,000	5,223,000,000
Unrealized loss position 12 months or more - unrealized loss	(213,000,000)	(185,000,000)
Unrealized loss position 12 months or more - fair value	2,526,000,000	5,503,000,000
Total unrealized loss	(518,000,000)	(207,000,000)
Total fair value	17,228,000,000	10,726,000,000
Corporate Stocks And Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss position less than 12 months - unrealized loss	(1,000,000)
Unrealized loss position less than 12 months - fair value	15,000,000
Unrealized loss position 12 months or more - unrealized loss		(1,000,000)
Unrealized loss position 12 months or more - fair value		15,000,000
Total unrealized loss	(1,000,000)	(1,000,000)
Total fair value	15,000,000	15,000,000
Residential And Commercial Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Quantifying Misstatement In Current Year Financial Statements Amount	$ 1,100,000,000