Fair Value (Recurring Fair Value Measurements) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Assets
Securities available for sale, fair value	$ 47,679,000,000	$ 44,235,000,000
Trading securities	2,334,000,000	2,353,000,000
Mortgage servicing rights	1,558,000,000	1,351,000,000
Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	47,252,000,000	43,794,000,000
Securities available for sale, fair value	47,679,000,000	44,235,000,000
Total financial derivatives	4,851,000,000	5,234,000,000
Trading securities	2,334,000,000	2,353,000,000
Trading loans	48,000,000	37,000,000
Total equity investments	1,616,000,000	1,621,000,000
Total customer resale agreements	150,000,000	155,000,000
Loans	941,000,000	1,034,000,000
Other assets	804,000,000	799,000,000
Total Assets	62,102,000,000	58,973,000,000
Liabilities
Total financial derivatives	3,827,000,000	4,027,000,000
Total trading securities sold short	1,429,000,000	1,490,000,000
Other liabilities	13,000,000	9,000,000
Other borrowed funds	224,000,000	273,000,000
Total liabilities	5,493,000,000	5,799,000,000
Fair Value Additional Information [Abstract]
Fair value net derivative assets	2,557,000,000	2,587,000,000
Fair value net derivative liabilities	1,391,000,000	1,383,000,000
Net unrealized gains (losses)	$ 18,000,000	$ 54,000,000
Percentage of Trading securities - debt comprised of US Treasury and government agencies securities	45.00%	57.00%
Percentage of Trading securities - debt comprised of residential mortgage-backed securities	37.00%	34.00%
US Treasury and Government Agencies Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	$ 6,095,000,000	$ 5,422,000,000
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	20,842,000,000	18,043,000,000
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,552,000,000	4,942,000,000
Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	1,994,000,000	2,187,000,000
Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,422,000,000	4,162,000,000
Asset backed [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	5,435,000,000	5,187,000,000
State and Municipal [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	2,058,000,000	2,038,000,000
Other Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	1,854,000,000	1,813,000,000
Corporate Stocks And Other [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Securities available for sale, fair value	427,000,000	441,000,000
Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	4,599,000,000	4,918,000,000
Liabilities
Total financial derivatives	3,112,000,000	3,272,000,000
BlackRock LTIP [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total financial derivatives	363,000,000	375,000,000
Other Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	252,000,000	316,000,000
Liabilities
Total financial derivatives	352,000,000	380,000,000
Residential Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	1,364,000,000	1,261,000,000
Mortgage servicing rights	1,015,000,000	845,000,000
Commercial Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	757,000,000	893,000,000
Mortgage servicing rights	543,000,000	506,000,000
Direct equity investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total equity investments	1,191,000,000	1,152,000,000
Fair Value Additional Information [Abstract]
Unfunded contractual commitments	26,000,000	28,000,000
Indirect Equity Investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total equity investments	425,000,000	469,000,000
Fair Value Additional Information [Abstract]
Unfunded contractual commitments	$ 118,000,000	112,000,000
Number of years over which distributions from indirect equity funds are expected to be received	12 years
BlackRock Series C Preferred Stock | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	$ 363,000,000	375,000,000
Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	441,000,000	424,000,000
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	2,323,000,000	2,332,000,000
Liabilities
Total trading securities sold short	1,429,000,000	1,490,000,000
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	11,000,000	21,000,000
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	5,476,000,000	4,795,000,000
Securities available for sale, fair value	5,841,000,000	5,221,000,000
Total financial derivatives	5,000,000	4,000,000
Trading securities	1,059,000,000	1,361,000,000
Other assets	248,000,000	190,000,000
Total Assets	7,153,000,000	6,776,000,000
Liabilities
Total financial derivatives	3,000,000
Total trading securities sold short	1,410,000,000	1,479,000,000
Total liabilities	1,413,000,000	1,479,000,000
Level 1 [Member] | US Treasury and Government Agencies Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	5,476,000,000	4,795,000,000
Level 1 [Member] | Corporate Stocks And Other [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Securities available for sale, fair value	365,000,000	426,000,000
Level 1 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	5,000,000	4,000,000
Liabilities
Total financial derivatives	3,000,000
Level 1 [Member] | Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	248,000,000	190,000,000
Level 1 [Member] | Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	1,048,000,000	1,340,000,000
Liabilities
Total trading securities sold short	1,410,000,000	1,479,000,000
Level 1 [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	11,000,000	21,000,000
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	36,772,000,000	33,474,000,000
Securities available for sale, fair value	36,834,000,000	33,489,000,000
Total financial derivatives	4,810,000,000	5,188,000,000
Trading securities	1,272,000,000	960,000,000
Trading loans	48,000,000	30,000,000
Total customer resale agreements	150,000,000	155,000,000
Loans	576,000,000	637,000,000
Other assets	186,000,000	226,000,000
Total Assets	45,230,000,000	41,940,000,000
Liabilities
Total financial derivatives	3,326,000,000	3,501,000,000
Total trading securities sold short	19,000,000	11,000,000
Other liabilities	3,000,000
Other borrowed funds	59,000,000	92,000,000
Total liabilities	3,407,000,000	3,604,000,000
Level 2 [Member] | US Treasury and Government Agencies Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	619,000,000	627,000,000
Level 2 [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	20,842,000,000	18,043,000,000
Level 2 [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	128,000,000	144,000,000
Level 2 [Member] | Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	1,994,000,000	2,187,000,000
Level 2 [Member] | Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,422,000,000	4,162,000,000
Level 2 [Member] | Asset backed [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,904,000,000	4,624,000,000
Level 2 [Member] | State and Municipal [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	2,042,000,000	1,904,000,000
Level 2 [Member] | Other Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	1,821,000,000	1,783,000,000
Level 2 [Member] | Corporate Stocks And Other [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Securities available for sale, fair value	62,000,000	15,000,000
Level 2 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	4,560,000,000	4,874,000,000
Liabilities
Total financial derivatives	3,101,000,000	3,260,000,000
Level 2 [Member] | Other Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	250,000,000	314,000,000
Liabilities
Total financial derivatives	225,000,000	241,000,000
Level 2 [Member] | Residential Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	1,354,000,000	1,255,000,000
Level 2 [Member] | Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	186,000,000	226,000,000
Level 2 [Member] | Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	1,272,000,000	960,000,000
Liabilities
Total trading securities sold short	19,000,000	11,000,000
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	5,004,000,000	5,525,000,000
Securities available for sale, fair value	5,004,000,000	5,525,000,000
Total financial derivatives	36,000,000	42,000,000
Trading securities	3,000,000	32,000,000
Trading loans		7,000,000
Total equity investments	1,616,000,000	1,621,000,000
Loans	365,000,000	397,000,000
Other assets	370,000,000	383,000,000
Total Assets	9,719,000,000	10,257,000,000
Liabilities
Total financial derivatives	498,000,000	526,000,000
Other liabilities	10,000,000	9,000,000
Other borrowed funds	165,000,000	181,000,000
Total liabilities	673,000,000	716,000,000
Level 3 [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,424,000,000	4,798,000,000
Level 3 [Member] | Asset backed [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	531,000,000	563,000,000
Level 3 [Member] | State and Municipal [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	16,000,000	134,000,000
Level 3 [Member] | Other Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	33,000,000	30,000,000
Level 3 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	34,000,000	40,000,000
Liabilities
Total financial derivatives	8,000,000	12,000,000
Level 3 [Member] | BlackRock LTIP [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total financial derivatives	363,000,000	375,000,000
Level 3 [Member] | Other Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	2,000,000	2,000,000
Liabilities
Total financial derivatives	127,000,000	139,000,000
Level 3 [Member] | Residential Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	10,000,000	6,000,000
Mortgage servicing rights	1,015,000,000	845,000,000
Level 3 [Member] | Commercial Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	757,000,000	893,000,000
Mortgage servicing rights	543,000,000	506,000,000
Level 3 [Member] | Direct equity investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total equity investments	1,191,000,000	1,152,000,000
Level 3 [Member] | Indirect Equity Investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total equity investments	425,000,000	469,000,000
Level 3 [Member] | BlackRock Series C Preferred Stock | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	363,000,000	375,000,000
Level 3 [Member] | Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	7,000,000	8,000,000
Level 3 [Member] | Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	$ 3,000,000	$ 32,000,000