Derivative Financial Instruments Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 159	$ (36)
Interest Rate Contract [Member] | Mortgage Related Income [Member] | Mortgage Servicing Rights [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	113	(93)
Interest Rate Contract [Member] | Mortgage Related Income [Member] | Loans Held-For-Sale [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(19)	46
Interest Rate Contract [Member] | Other Income [Member] | Loans Held-For-Investment [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(1)	2
Interest Rate Contract [Member] | Other Trading [Member] | Other Trading [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	14	9
Foreign Exchange Contract [Member] | Other Trading [Member] | Other Trading [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	5	(2)
Credit Risk Contract [Member] | Other Income [Member] | Loans Held-For-Investment [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(10)	1
Credit Risk Contract [Member] | Other Trading [Member] | Other Trading [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	6	6
Equity Contract [Member] | Other Trading [Member] | Other Trading [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	18	1
Other Contract [Member] | Mortgage Related and Commercial Real Estate Related Income [Member] | Interest Rate Lock Commitments [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 33	$ (6)