Amount Recorded in Income Statements for Foreign Currency Forward Contracts Not Designated as Hedges (Detail) - Not Designated as Hedging Instrument - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ 0	$ (21)	$ (53)	$ (24)
Interest rate contracts | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(2)	(2)	(4)	(4)
Foreign exchange contracts | Investment income and other
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ 2	$ (19)	$ (49)	$ (20)