Variable Interest Entities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Loans held for investment	$ 86,507	$ 80,014
Non Interest Expenses
Variable Interest Entity [Line Items]
Losses from LIHC investments included in other noninterest expense	(7)	(13)	$ (8)
Income Tax Expense
Variable Interest Entity [Line Items]
Amortization of LIHC investments included in income tax expense	136	185	129
Tax credits and other tax benefits from LIHC investments included in income tax expense	180	193	$ 188
Unconsolidated VIEs
Variable Interest Entity [Line Items]
Loans held for investment	217	276
Unconsolidated VIEs | LIHC investments
Variable Interest Entity [Line Items]
Loans held for investment	198	228
Unconsolidated VIEs | Leasing investments
Variable Interest Entity [Line Items]
Loans held for investment	19	24
Unconsolidated VIEs | Other investments
Variable Interest Entity [Line Items]
Loans held for investment	$ 0	$ 24