Fair Value Measurements - Summary of Net Gains and Losses on Foreign Currency Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative gain (loss)		$ (3)		$ (3)
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative gain (loss)	$ (11)	$ 0	$ (9)	$ 3