Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Accounts receivable, net of allowance	$ 20	$ 23
Common Class A
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	122,414,827	88,578,361
Common stock outstanding (in shares)	122,414,827	88,578,361
Common Class B
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	391,970,996	421,450,000
Common stock outstanding (in shares)	391,970,996	421,450,000