Derivative Financial Instruments - Information about Fair Values of Derivative Instruments in Consolidated Statement of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, derivatives	$ 36	$ 46	$ 42
Interest rate swap agreements | Designated as Hedging Instrument | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives in fair value hedging relationships, derivative	(111)	22	(109)
Derivatives in fair value hedging relationships, hedged item	$ 111	$ (21)	$ 109
Interest rate swap agreements | Fixed Rate Long-Term Borrowings | Designated as Hedging Instrument | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other costs of operations	Other costs of operations	Other costs of operations
Derivatives in fair value hedging relationships, derivative	$ (111)	$ 22	$ (109)
Derivatives in fair value hedging relationships, hedged item	111	(21)	109
Interest rate swap agreements | Fixed Rate Available For Sale Securities | Designated as Hedging Instrument | Fair Value Hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives in fair value hedging relationships, derivative	0
Derivatives in fair value hedging relationships, hedged item	0
Interest Rate Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, derivatives	15	31	28
Foreign exchange and other option and futures contracts
Derivative Instruments, Gain (Loss) [Line Items]
Derivatives not designated as hedging instruments, derivatives	$ 21	$ 15	$ 14