Fair Value (Recurring Fair Value Measurements) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Assets
Securities available for sale, fair value	$ 56,884,000,000	$ 55,760,000,000
Trading securities	2,006,000,000	1,726,000,000
Mortgage servicing rights	1,222,000,000	1,589,000,000
Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	56,400,000,000	55,171,000,000
Securities available for sale, fair value	56,884,000,000	55,760,000,000
Total financial derivatives	8,227,000,000	4,941,000,000
Trading securities	2,006,000,000	1,726,000,000
Total customer resale agreements	137,000,000	137,000,000
Loans	851,000,000	905,000,000
Other assets	634,000,000	817,000,000
Total Assets	73,459,000,000	68,804,000,000
Liabilities
Total financial derivatives	6,068,000,000	3,802,000,000
Total trading securities sold short	1,046,000,000	987,000,000
Other borrowed funds	70,000,000	93,000,000
Other liabilities	13,000,000	10,000,000
Total liabilities	7,197,000,000	4,892,000,000
Fair Value Additional Information [Abstract]
Fair value net derivative assets	2,976,000,000	1,836,000,000
Fair value net derivative liabilities	583,000,000	640,000,000
Net unrealized gains (losses)	79,000,000	23,000,000
US Treasury and Government Agencies Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	10,098,000,000	9,874,000,000
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	25,768,000,000	24,820,000,000
Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	3,689,000,000	4,151,000,000
Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	1,763,000,000	1,918,000,000
Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,604,000,000	4,903,000,000
Asset backed [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	5,697,000,000	5,423,000,000
State and Municipal [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	2,100,000,000	2,056,000,000
Other Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	2,681,000,000	2,026,000,000
Corporate Stocks And Other [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Securities available for sale, fair value	484,000,000	589,000,000
Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	7,808,000,000	4,655,000,000
Liabilities
Total financial derivatives	5,469,000,000	3,132,000,000
BlackRock LTIP [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total financial derivatives	209,000,000	357,000,000
Other Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	419,000,000	286,000,000
Liabilities
Total financial derivatives	390,000,000	313,000,000
Residential Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	1,116,000,000	843,000,000
Mortgage servicing rights	774,000,000	1,063,000,000
Commercial Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	981,000,000	641,000,000
Mortgage servicing rights	448,000,000	526,000,000
Direct equity investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Equity investments - direct investments	1,120,000,000	1,098,000,000
Fair Value Additional Information [Abstract]
Direct Investments - Unfunded Commitments	22,000,000	23,000,000
Indirect Equity Investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Equity investments - indirect investments	281,000,000	347,000,000
Fair Value Additional Information [Abstract]
Indirect Investments - Unfunded Commitments	$ 109,000,000	103,000,000
Indirect Investments - Estimated remaining liquidation period	12 years
BlackRock Series C Preferred Stock | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	$ 209,000,000	357,000,000
Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	425,000,000	460,000,000
Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	1,994,000,000	1,717,000,000
Liabilities
Total trading securities sold short	1,046,000,000	987,000,000
Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	12,000,000	9,000,000
Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	9,483,000,000	9,267,000,000
Securities available for sale, fair value	9,904,000,000	9,794,000,000
Trading securities	811,000,000	996,000,000
Other assets	254,000,000	254,000,000
Total Assets	10,969,000,000	11,044,000,000
Liabilities
Total financial derivatives	3,000,000	1,000,000
Total trading securities sold short	1,036,000,000	960,000,000
Total liabilities	1,039,000,000	961,000,000
Level 1 [Member] | US Treasury and Government Agencies Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	9,483,000,000	9,267,000,000
Level 1 [Member] | Corporate Stocks And Other [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Securities available for sale, fair value	421,000,000	527,000,000
Level 1 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total financial derivatives	3,000,000	1,000,000
Level 1 [Member] | Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	254,000,000	254,000,000
Level 1 [Member] | Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	799,000,000	987,000,000
Liabilities
Total trading securities sold short	1,036,000,000	960,000,000
Level 1 [Member] | Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	12,000,000	9,000,000
Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	42,876,000,000	41,369,000,000
Securities available for sale, fair value	42,939,000,000	41,431,000,000
Total financial derivatives	8,176,000,000	4,910,000,000
Trading securities	1,193,000,000	727,000,000
Total customer resale agreements	137,000,000	137,000,000
Loans	534,000,000	565,000,000
Other assets	165,000,000	199,000,000
Total Assets	54,254,000,000	48,807,000,000
Liabilities
Total financial derivatives	5,680,000,000	3,328,000,000
Total trading securities sold short	10,000,000	27,000,000
Other borrowed funds	62,000,000	81,000,000
Total liabilities	5,752,000,000	3,436,000,000
Level 2 [Member] | US Treasury and Government Agencies Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	615,000,000	607,000,000
Level 2 [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	25,768,000,000	24,820,000,000
Level 2 [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	132,000,000	143,000,000
Level 2 [Member] | Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	1,763,000,000	1,918,000,000
Level 2 [Member] | Commercial mortgage-backed securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,604,000,000	4,903,000,000
Level 2 [Member] | Asset backed [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	5,261,000,000	4,941,000,000
Level 2 [Member] | State and Municipal [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	2,085,000,000	2,041,000,000
Level 2 [Member] | Other Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	2,648,000,000	1,996,000,000
Level 2 [Member] | Corporate Stocks And Other [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Securities available for sale, fair value	63,000,000	62,000,000
Level 2 [Member] | Interest Rate Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	7,761,000,000	4,626,000,000
Liabilities
Total financial derivatives	5,455,000,000	3,124,000,000
Level 2 [Member] | Other Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	415,000,000	284,000,000
Liabilities
Total financial derivatives	225,000,000	204,000,000
Level 2 [Member] | Residential Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	1,110,000,000	838,000,000
Level 2 [Member] | Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	165,000,000	199,000,000
Level 2 [Member] | Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	1,193,000,000	727,000,000
Liabilities
Total trading securities sold short	10,000,000	27,000,000
Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	4,041,000,000	4,535,000,000
Securities available for sale, fair value	4,041,000,000	4,535,000,000
Total financial derivatives	51,000,000	31,000,000
Trading securities	2,000,000	3,000,000
Loans	317,000,000	340,000,000
Other assets	215,000,000	364,000,000
Total Assets	8,188,000,000	8,606,000,000
Liabilities
Total financial derivatives	385,000,000	473,000,000
Other borrowed funds	8,000,000	12,000,000
Other liabilities	13,000,000	10,000,000
Total liabilities	406,000,000	495,000,000
Level 3 [Member] | Residential mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	3,557,000,000	4,008,000,000
Level 3 [Member] | Asset backed [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	436,000,000	482,000,000
Level 3 [Member] | State and Municipal [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total debt securities	15,000,000	15,000,000
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	47,000,000	29,000,000
Liabilities
Total financial derivatives	11,000,000	7,000,000
Level 3 [Member] | BlackRock LTIP [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities
Total financial derivatives	209,000,000	357,000,000
Level 3 [Member] | Other Contracts [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Total financial derivatives	4,000,000	2,000,000
Liabilities
Total financial derivatives	165,000,000	109,000,000
Level 3 [Member] | Residential Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	6,000,000	5,000,000
Mortgage servicing rights	774,000,000	1,063,000,000
Level 3 [Member] | Commercial Mortgage [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Loans held for sale	981,000,000	641,000,000
Mortgage servicing rights	448,000,000	526,000,000
Level 3 [Member] | Direct equity investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Equity investments - direct investments	1,120,000,000	1,098,000,000
Level 3 [Member] | Indirect Equity Investments [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Equity investments - indirect investments	233,000,000
Level 3 [Member] | BlackRock Series C Preferred Stock | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	209,000,000	357,000,000
Level 3 [Member] | Other Assets [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Other assets	6,000,000	7,000,000
Level 3 [Member] | Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Assets
Trading securities	$ 2,000,000	$ 3,000,000