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Equity - Narrative (Detail) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Non-cash stock-based compensation expense	$ 7		$ 42	$ 35
Share-based compensation liability		$ 5		5
Share-Based Payment Arrangement, Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation liability	15		15
Restricted Stock Units (RSUs)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Non-cash stock-based compensation expense			12
Restricted Stock Units (RSUs) \| Restructuring Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Non-cash stock-based compensation expense			2
Performance Share Units (PSUs)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Non-cash stock-based compensation expense	1		2
Additional Paid-in Capital
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Non-cash stock-based compensation expense			27	$ 30
Additional Paid-in Capital \| Share-Based Payment Arrangement, Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation liability	5		5
Additional Paid-in Capital \| Restricted Stock Units (RSUs)
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Non-cash stock-based compensation expense	$ 2		$ 12
Common Stock \| Class A Common Stock
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares issued under the Plan (in shares)			869
Shares issued under Omnibus Incentive Plan (in shares)	17	1	273	187