Derivative Positions (Additional Information) (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivative, Notional Amount	$ 255,352	$ 233,052
Credit Risk Contract [Member]
Derivative Asset, Notional Amount	7	6
Derivative Liability, Notional Amount	41	33
Other Contract [Member] | Visa Interest [Member]
Derivative Liability, Notional Amount	41	41
Interest rate futures [Member] | Mortgage Servicing Rights [Member]
Derivative, Notional Amount	1,100	921
Interest rate futures [Member] | Loans Held-For-Sale [Member]
Derivative, Notional Amount	32	116
Interest rate futures [Member] | Other Trading [Member]
Derivative, Notional Amount	2,000	1,200
Equity Futures [Member] | Equity Contract [Member]
Derivative, Notional Amount	$ 191	$ 136