Stock-based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2025 USD ($) $ / shares shares
Weighted Average Price
Beginning balance (in dollars per share) | $ / shares	$ 46.51
Granted (in dollars per share) | $ / shares	82.15
Exercised (in dollars per share) | $ / shares	39.99
Forfeited or expired (in dollars per share) | $ / shares	67.00
Ending balance (in dollars per share) | $ / shares	65.42
Exercisable (in dollars per share) | $ / shares	$ 62.05
Shares Subject to Option/SAR
Beginning balance (in shares) | shares	4,244,782
Granted (in shares) | shares	530,251
Exercised (in shares) | shares	(2,812,821)
Forfeited or expired (in shares) | shares	(66,609)
Ending balance (in shares) | shares	1,895,603
Exercisable (in shares) | shares	688,036
Weighted Average Remaining Contractual Life (years)
Outstanding	8 years 25 days
Exercisable	7 years 3 months 21 days
Aggregate Intrinsic Value (in millions)
Outstanding | $	$ 84
Exercisable | $	$ 33