Share-based Compensation - Schedule of Performance-based Shares Activity Disclosure (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Aggregate Intrinsic Value
Stock price used to calculate aggregate intrinsic value (in dollars per share)	$ 341.38	$ 274.95
Performance-based Shares
Shares
Beginning balance (in shares)	1,084,232
Granted (in shares)	476,480
Vested and earned (in shares)	(429,430)
Unearned (in shares)	(37,340)
Forfeited (in shares)	(36,986)
Ending balance (in shares)	1,056,956	1,084,232
Weighted- Average Grant Date Fair Value
Beginning balance (in dollars per share)	$ 251.41
Granted (in dollars per share)	345.65
Vested and earned (in dollars per share)	234.54
Unearned (in dollars per share)	312.72
Forfeited (in dollars per share)	296.57
Ending balance (in dollars per share)	$ 297.00	$ 251.41
Weighted- Average Remaining Contractual Term (in years)
Outstanding as of September 30, 2025	7 months 20 days
Aggregate Intrinsic Value
Outstanding as of September 30, 2025	$ 361