Fair Value, Option, Carrying Amount (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgages held for sale	$ 21,539	$ 15,565
Loans held for sale	0	1
Loans	5,651	5,788
Other assets, carried at fair value	2,636	2,512
Trading assets - loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Trading assets, loans	1,804	1,387
Trading assets, loans, unpaid principal	1,827	1,410
Trading assets, loans, aggregate difference	(23)	(23)
Nonaccrual loans	5	0
Nonaccrual loans, unpaid principal	6	1
Nonaccrual loans, Aggregate difference	(1)	(1)
Mortgages held for sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgages held for sale	21,539	15,565
Mortgages held for sale, unpaid principal	21,227	15,246
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	312	319
Nonaccrual loans	128	160
Nonaccrual loans, unpaid principal	207	252
Nonaccrual loans, Aggregate difference	(79)	(92)
Loans 90 days or more past due and still accruing	26	27
Loans 90 days or more past due and still accruing, Unpaid principal	30	30
Loans 90 days or more past due and still accruing, Aggregate difference	(4)	(3)
Loans held for sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans held for sale	0	1
Loans held for sale, unpaid principal	10	10
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	(10)	(9)
Nonaccrual loans	0	1
Nonaccrual loans, unpaid principal	10	10
Nonaccrual loans, Aggregate difference	(10)	(9)
Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans	5,651	5,788
Loans, Unpaid principal	5,438	5,527
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	213	261
Nonaccrual loans	494	367
Nonaccrual loans, unpaid principal	508	376
Nonaccrual loans, Aggregate difference	(14)	(9)
Other assets [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Other assets, carried at fair value	$ 2,636	$ 2,512