Financial Instruments and Fair Value Measurements - Summary of Undesignated Financial Instruments Exercised and Realized and Unrealized Gains (Losses) in Foreign Currency and Derivative Gains (Losses) Net (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) Contract	Sep. 30, 2019 USD ($) Contract	Sep. 30, 2020 USD ($) Contract	Sep. 30, 2019 USD ($) Contract
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Exercised contracts | Contract	28	34	101	82
Realized gains on the matured, expired or settled contracts	$ 1	$ 11	$ 11	$ 18
Unrealized gains (losses) on the change in fair value of outstanding contracts	$ (27)	$ 9	$ 7	$ 13