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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 210	$ 59	$ 363	$ (4)
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	156	(37)	270	(157)
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	(26)	1	(45)	48
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	(2)	1	(3)	3
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	20	21	34	30
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	(4)	42	(6)	40
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	(5)	(1)	(15)	(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	7	5	13	11
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	10	1	28	2
Other Contract [Member] | Other Trading [Member] | Commodity Contract [Member]
Derivative Instruments not Designated as Hedging Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	1	0	1	0
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	$ 53	$ 26	$ 86	$ 20