Fair Value, Option, Carrying Amount (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgages held for sale	$ 17,627	$ 15,565
Loans held for sale	0	1
Loans	5,529	5,788
Other assets, carried at fair value	2,745	2,512
Trading assets - loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Trading assets, loans	805	1,387
Trading assets, loans, unpaid principal	850	1,410
Trading assets, loans, aggregate difference	(45)	(23)
Nonaccrual loans	0	0
Nonaccrual loans, unpaid principal	0	1
Nonaccrual loans, Aggregate difference	0	(1)
Mortgages held for sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgages held for sale	17,627	15,565
Mortgages held for sale, unpaid principal	17,027	15,246
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	600	319
Nonaccrual loans	81	160
Nonaccrual loans, unpaid principal	137	252
Nonaccrual loans, Aggregate difference	(56)	(92)
Loans 90 days or more past due and still accruing	19	27
Loans 90 days or more past due and still accruing, Unpaid principal	21	30
Loans 90 days or more past due and still accruing, Aggregate difference	(2)	(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	5	10
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	(5)	(9)
Nonaccrual loans	0	1
Nonaccrual loans, unpaid principal	5	10
Nonaccrual loans, Aggregate difference	(5)	(9)
Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans	5,529	5,788
Loans, Unpaid principal	5,319	5,527
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	210	261
Nonaccrual loans	406	367
Nonaccrual loans, unpaid principal	422	376
Nonaccrual loans, Aggregate difference	(16)	(9)
Other assets [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Other assets, carried at fair value	$ 2,745	$ 2,512