Fair Value (Reconciliation of Recurring Fair Value Measurements) (Details) - Fair Value, Measurements, Recurring [Member] - Level 3 [Member] - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 10,650,000,000	$ 10,078,000,000	$ 11,064,000,000	$ 10,257,000,000	$ 10,650,000,000
Included in earnings		276,000,000	110,000,000	386,000,000	195,000,000
Included in other comprehensive income		(3,000,000)	44,000,000	(14,000,000)	118,000,000
Purchases		218,000,000	144,000,000	400,000,000	247,000,000
Sales		(187,000,000)	(254,000,000)	(315,000,000)	(303,000,000)
Issuances		1,049,000,000	30,000,000	2,163,000,000	60,000,000
Settlements		(1,700,000,000)	(421,000,000)	(3,126,000,000)	(254,000,000)
Transfers Into Level 3		7,000,000	4,000,000	13,000,000	46,000,000
Transfers Out of Level 3		(19,000,000)	(29,000,000)	(45,000,000)	(67,000,000)
Ending Balance		9,719,000,000	10,692,000,000	9,719,000,000	10,692,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		223,000,000	43,000,000	237,000,000	59,000,000
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	638,000,000	710,000,000	633,000,000	716,000,000	638,000,000
Included in earnings		(12,000,000)	23,000,000	30,000,000	67,000,000
Sales		1,000,000		1,000,000	1,000,000
Issuances		21,000,000	10,000,000	46,000,000	19,000,000
Settlements		(47,000,000)	(29,000,000)	(120,000,000)	(88,000,000)
Ending Balance		673,000,000	637,000,000	673,000,000	637,000,000
Unrealized gains or (losses) on liabilities held on Consolidated Balance Sheet		(25,000,000)	16,000,000	(17,000,000)	22,000,000
Fair Value Additional Information [Abstract]
Net gains (losses) included in earnings (realized and unrealized) relating to Level 3 assets and liabilities		288,000,000	87,000,000	356,000,000	128,000,000
Amortization and accretion included in earnings relating to Level 3 assets and liabilities		37,000,000	44,000,000	77,000,000	85,000,000
Net unrealized gains (losses) relating to Level 3 assets and liabilities		248,000,000	27,000,000	254,000,000	37,000,000
Available-for-sale Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,370,000,000	5,338,000,000	6,239,000,000	5,525,000,000	6,370,000,000
Included in earnings		36,000,000	44,000,000	75,000,000	81,000,000
Included in other comprehensive income		(3,000,000)	44,000,000	(14,000,000)	118,000,000
Purchases			1,000,000	3,000,000	1,000,000
Sales			(1,000,000)		(7,000,000)
Settlements		(367,000,000)	(225,000,000)	(585,000,000)	(461,000,000)
Ending Balance		5,004,000,000	6,102,000,000	5,004,000,000	6,102,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet			(1,000,000)	(1,000,000)	(3,000,000)
Available-for-sale Securities [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	5,358,000,000	4,624,000,000	5,234,000,000	4,798,000,000	5,358,000,000
Included in earnings		30,000,000	40,000,000	55,000,000	74,000,000
Included in other comprehensive income		(8,000,000)	31,000,000	(22,000,000)	85,000,000
Settlements		(222,000,000)	(198,000,000)	(407,000,000)	(410,000,000)
Ending Balance		4,424,000,000	5,107,000,000	4,424,000,000	5,107,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet			(1,000,000)	(1,000,000)	(3,000,000)
Available-for-sale Securities [Member] | Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Non-agency [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Included in earnings		1,000,000		8,000,000
Settlements		(1,000,000)		(8,000,000)
Available-for-sale Securities [Member] | Asset backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	641,000,000	548,000,000	642,000,000	563,000,000	641,000,000
Included in earnings		5,000,000	4,000,000	11,000,000	8,000,000
Included in other comprehensive income		5,000,000		9,000,000	19,000,000
Settlements		(27,000,000)	(27,000,000)	(52,000,000)	(49,000,000)
Ending Balance		531,000,000	619,000,000	531,000,000	619,000,000
Available-for-sale Securities [Member] | State and Municipal [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	333,000,000	133,000,000	331,000,000	134,000,000	333,000,000
Included in earnings					(2,000,000)
Included in other comprehensive income			13,000,000	(1,000,000)	14,000,000
Settlements		(117,000,000)	1,000,000	(117,000,000)
Ending Balance		16,000,000	345,000,000	16,000,000	345,000,000
Available-for-sale Securities [Member] | Other debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	38,000,000	33,000,000	32,000,000	30,000,000	38,000,000
Included in earnings				1,000,000	1,000,000
Purchases			1,000,000	3,000,000	1,000,000
Sales		0	(1,000,000)		(7,000,000)
Settlements			(1,000,000)	(1,000,000)	(2,000,000)
Ending Balance		33,000,000	31,000,000	33,000,000	31,000,000
Financial Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	36,000,000	54,000,000	30,000,000	42,000,000	36,000,000
Included in earnings		16,000,000	59,000,000	87,000,000	119,000,000
Purchases			1,000,000	1,000,000	1,000,000
Settlements		(34,000,000)	(49,000,000)	(94,000,000)	(115,000,000)
Ending Balance		36,000,000	41,000,000	36,000,000	41,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		33,000,000	47,000,000	76,000,000	80,000,000
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	439,000,000	529,000,000	440,000,000	526,000,000	439,000,000
Included in earnings		(15,000,000)	30,000,000	26,000,000	70,000,000
Sales		1,000,000		1,000,000	1,000,000
Settlements		(17,000,000)	(16,000,000)	(55,000,000)	(56,000,000)
Ending Balance		498,000,000	454,000,000	498,000,000	454,000,000
Unrealized gains or (losses) on liabilities held on Consolidated Balance Sheet		(25,000,000)	16,000,000	(17,000,000)	22,000,000
Trading Securities - Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	32,000,000	3,000,000	32,000,000	32,000,000	32,000,000
Included in earnings			1,000,000		1,000,000
Settlements				(29,000,000)
Ending Balance		3,000,000	33,000,000	3,000,000	33,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet			2,000,000		2,000,000
Trading Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		2,000,000		7,000,000
Sales		(2,000,000)		(7,000,000)
Ending Balance		0		0
Mortgage Servicing Rights [Member] | Residential Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,087,000,000	839,000,000	1,039,000,000	845,000,000	1,087,000,000
Included in earnings		135,000,000	(57,000,000)	68,000,000	(116,000,000)
Purchases		67,000,000		150,000,000	17,000,000
Issuances		21,000,000	20,000,000	38,000,000	43,000,000
Settlements		(47,000,000)	(35,000,000)	(86,000,000)	(64,000,000)
Ending Balance		1,015,000,000	967,000,000	1,015,000,000	967,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		134,000,000	(57,000,000)	72,000,000	(114,000,000)
Mortgage Servicing Rights [Member] | Commercial Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		494,000,000	529,000,000	506,000,000
Included in earnings		34,000,000	(11,000,000)	18,000,000	(25,000,000)
Purchases		17,000,000	9,000,000	28,000,000	16,000,000
Issuances		20,000,000	10,000,000	34,000,000	17,000,000
Settlements	552,000,000	(22,000,000)	(22,000,000)	(43,000,000)	507,000,000
Ending Balance		543,000,000	515,000,000	543,000,000	515,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		34,000,000	(11,000,000)	18,000,000	(25,000,000)
Loans Held For Sale [Member] | Residential Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	8,000,000	7,000,000	5,000,000	6,000,000	8,000,000
Included in earnings			1,000,000		1,000,000
Purchases		11,000,000	3,000,000	17,000,000	8,000,000
Sales		(2,000,000)	(1,000,000)	(2,000,000)	(3,000,000)
Settlements		(1,000,000)	(1,000,000)	(1,000,000)	(1,000,000)
Transfers Into Level 3		1,000,000	1,000,000	2,000,000	4,000,000
Transfers Out of Level 3		(6,000,000)	(4,000,000)	(12,000,000)	(13,000,000)
Ending Balance		10,000,000	4,000,000	10,000,000	4,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet			1,000,000		1,000,000
Loans Held For Sale [Member] | Commercial Mortgage [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	586,000,000	975,000,000	577,000,000	893,000,000	586,000,000
Included in earnings		23,000,000	5,000,000	44,000,000	7,000,000
Sales		(56,000,000)		(56,000,000)
Issuances		1,008,000,000		2,091,000,000
Settlements		(1,193,000,000)	(61,000,000)	(2,215,000,000)	(72,000,000)
Ending Balance		757,000,000	521,000,000	757,000,000	521,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet			5,000,000	2,000,000	7,000,000
Equity Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,664,000,000	1,591,000,000	1,757,000,000	1,621,000,000	1,664,000,000
Included in earnings		48,000,000	53,000,000	91,000,000	105,000,000
Purchases		100,000,000	105,000,000	146,000,000	180,000,000
Sales		(123,000,000)	(120,000,000)	(242,000,000)	(155,000,000)
Settlements			(2,000,000)		(1,000,000)
Ending Balance		1,616,000,000	1,793,000,000	1,616,000,000	1,793,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		42,000,000	44,000,000	73,000,000	94,000,000
Equity Investments [Member] | Direct equity investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	1,069,000,000	1,149,000,000	1,163,000,000	1,152,000,000	1,069,000,000
Included in earnings		27,000,000	38,000,000	56,000,000	72,000,000
Purchases		95,000,000	99,000,000	138,000,000	168,000,000
Sales		(80,000,000)	(81,000,000)	(155,000,000)	(90,000,000)
Ending Balance		1,191,000,000	1,219,000,000	1,191,000,000	1,219,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		22,000,000	30,000,000	40,000,000	63,000,000
Equity Investments [Member] | Indirect Equity Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	595,000,000	442,000,000	594,000,000	469,000,000	595,000,000
Included in earnings		21,000,000	15,000,000	35,000,000	33,000,000
Purchases		5,000,000	6,000,000	8,000,000	12,000,000
Sales		(43,000,000)	(39,000,000)	(87,000,000)	(65,000,000)
Settlements			(2,000,000)		(1,000,000)
Ending Balance		425,000,000	574,000,000	425,000,000	574,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		20,000,000	14,000,000	33,000,000	31,000,000
Loans [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	527,000,000	383,000,000	518,000,000	397,000,000	527,000,000
Included in earnings		5,000,000	10,000,000	15,000,000	19,000,000
Purchases		23,000,000	25,000,000	55,000,000	24,000,000
Sales		(4,000,000)	(132,000,000)	(8,000,000)	(138,000,000)
Settlements		(35,000,000)	(26,000,000)	(72,000,000)	(47,000,000)
Transfers Into Level 3		6,000,000	3,000,000	11,000,000	42,000,000
Transfers Out of Level 3		(13,000,000)	(25,000,000)	(33,000,000)	(54,000,000)
Ending Balance		365,000,000	373,000,000	365,000,000	373,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		1,000,000	8,000,000	9,000,000	14,000,000
Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	340,000,000	392,000,000	338,000,000	383,000,000	340,000,000
Included in earnings		(21,000,000)	5,000,000	(12,000,000)	3,000,000
Settlements		(1,000,000)		(1,000,000)
Ending Balance		370,000,000	343,000,000	370,000,000	343,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		(21,000,000)	5,000,000	(12,000,000)	3,000,000
Other Assets [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	8,000,000	8,000,000	8,000,000	8,000,000	8,000,000
Settlements		(1,000,000)		(1,000,000)
Ending Balance		7,000,000	8,000,000	7,000,000	8,000,000
Other Assets [Member] | BlackRock Series C Preferred Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	332,000,000	384,000,000	330,000,000	375,000,000	332,000,000
Included in earnings		(21,000,000)	5,000,000	(12,000,000)	3,000,000
Ending Balance		363,000,000	335,000,000	363,000,000	335,000,000
Unrealized gains or (losses) on assets held on Consolidated Balance Sheet		(21,000,000)	5,000,000	(12,000,000)	3,000,000
Other Borrowed Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 199,000,000	171,000,000	193,000,000	181,000,000	199,000,000
Included in earnings		3,000,000	(7,000,000)	3,000,000	(3,000,000)
Issuances		21,000,000	10,000,000	46,000,000	19,000,000
Settlements		(30,000,000)	(13,000,000)	(65,000,000)	(32,000,000)
Ending Balance		165,000,000	$ 183,000,000	165,000,000	$ 183,000,000
Other Liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance		10,000,000		9,000,000
Included in earnings				1,000,000
Ending Balance		$ 10,000,000		$ 10,000,000