Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 46	$ 42	$ 21
Interest Rate Swap Agreements [Member] | Fixed Rate Long-Term Borrowings [Member] | Derivatives Designated and Qualifying as Hedging Instruments [Member] | Fair Value Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives in fair value hedging relationships, Derivatives	$ 22	$ (109)	$ (59)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Noninterest Expense	Other Noninterest Expense	Other Noninterest Expense
Derivatives in fair value hedging relationships, Hedged item	$ (21)	$ 109	$ 58
Interest Rate Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	31	28	12
Foreign Exchange and Other Option and Futures Contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, Derivatives	$ 15	$ 14	$ 9