Share-Based Compensation Expense - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Performance-based RSUs [Member]
Class Of Stock [Line Items]
Aggregate grant date fair value			$ 7
Total future compensation expense	$ 222
Remaining weighted-average amortization period	2 years
RSUs [Member]
Class Of Stock [Line Items]
Aggregate grant date fair value			$ 43
Total future compensation expense	$ 116
Remaining weighted-average amortization period	1 year 7 months 6 days
RSUs and PRSUs[Member]
Class Of Stock [Line Items]
Share-based compensation	$ 33	$ 2
Service-Based Portion | Minimum
Class Of Stock [Line Items]
Vesting period	2 years
Service-Based Portion | Maximum
Class Of Stock [Line Items]
Vesting period	5 years
2021 Omnibus Incentive Plan | Time-based RSUs [Member]
Class Of Stock [Line Items]
Vesting period			3 years
Percentage of units granted subject to vesting requirements			55.00%
2021 Omnibus Incentive Plan | Performance-based RSUs [Member]
Class Of Stock [Line Items]
Percentage of units granted subject to vesting requirements			45.00%