Fair Value, Option, Carrying Amount (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgages held for sale	$ 22,647	$ 13,539
Loans	4,788	5,316
Other assets, carried at fair value	3,441	3,065
Trading assets - loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Trading assets, loans	738	886
Trading assets, loans, unpaid principal	788	935
Trading assets, loans, aggregate difference	(50)	(49)
Nonaccrual loans	49	0
Nonaccrual loans, unpaid principal	57	0
Nonaccrual loans, Aggregate difference	(8)	0
Mortgages held for sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgages held for sale	22,647	13,539
Mortgages held for sale, unpaid principal	21,857	13,265
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	790	274
Nonaccrual loans	136	161
Nonaccrual loans, unpaid principal	179	228
Nonaccrual loans, Aggregate difference	(43)	(67)
Loans 90 days or more past due and still accruing	14	19
Loans 90 days or more past due and still accruing, Unpaid principal	17	22
Loans 90 days or more past due and still accruing, Aggregate difference	(3)	(3)
Loans held for sale [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans held for sale	0	0
Loans held for sale, unpaid principal	6	5
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	(6)	(5)
Nonaccrual loans	0	0
Nonaccrual loans, unpaid principal	6	5
Nonaccrual loans, Aggregate difference	(6)	(5)
Loans [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans	4,788	5,316
Loans, Unpaid principal	4,692	5,184
Loans, Loans held for sale and Mortgages held for sale, aggregate difference	96	132
Nonaccrual loans	277	305
Nonaccrual loans, unpaid principal	295	322
Nonaccrual loans, Aggregate difference	(18)	(17)
Other assets [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Other assets, carried at fair value	$ 3,441	$ 3,065