Share-based Compensation - Schedule of Options Activity Disclosure (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Stock Options Additional Disclosures
Stock price used to calculate aggregate intrinsic value (in dollars per share)	$ 341.38	$ 274.95
Stock Option
Options
Beginning balance (in shares)	5,364,732
Granted (in shares)	643,847
Forfeited (in shares)	(67,105)
Exercised (in shares)	(1,317,262)
Ending balance (in shares)	4,624,212
Options exercisable at end of period (in shares)	3,320,491
Options exercisable and expected to vest at end of period (in shares)	4,590,205
Weighted- Average Exercise Price
Beginning balance (in dollars per share)	$ 183.02
Granted (in dollars per share)	311.85
Forfeited (in dollars per share)	262.89
Exercised (in dollars per share)	155.33
Ending balance (in dollars per share)	207.69
Options exercisable at end of period (in dollars per share)	182.37
Options exercisable and expected to vest at end of period (in dollars per share)	$ 207.06
Stock Options Additional Disclosures
Weighted-average remaining contractual term, Outstanding as of September 30, 2024	5 years 11 months 1 day
Weighted-average remaining contractual term, Options exercisable as of September 30, 2024	4 years 11 months 8 days
Weighted-average remaining contractual term, Options exercisable and expected to vest as of September 30, 2024	5 years 10 months 24 days
Aggregate intrinsic value, Outstanding as of September 30, 2024	$ 618
Aggregate intrinsic value, Options exercisable as of September 30, 2024	528
Aggregate intrinsic value, Options exercisable and expected to vest at September 30, 2024	$ 617