Stock-Based Employee Benefit Plans - Summary of Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2025 USD ($) $ / shares shares
Shares
Beginning balance (in shares) | shares	189
Granted (in shares) | shares	5
Exercised (in shares) | shares	(65)
Ending balance (in shares) | shares	129
Exercisable (in shares) | shares	65
Vested and expected to vest (in shares) | shares	127
Weighted- average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 479.26
Granted (in dollars per share) | $ / shares	2,014.89
Exercised (in dollars per share) | $ / shares	224.16
Ending balance (in dollars per share) | $ / shares	670.08
Exercisable (in dollars per share) | $ / shares	457.59
Vested and expected to vest (in dollars per share) | $ / shares	$ 664.36
Weighted- average Remaining Contractual Term
Weighted- average Remaining Contractual Term (in years)	3 years 5 months 4 days
Exercisable (in years)	2 years 1 month 9 days
Vested and expected to vest (in years)	3 years 4 months 28 days
Aggregate Intrinsic value | $	$ 109,164
Aggregate Intrinsic value, Exercisable | $	67,464
Aggregate Intrinsic value, Vested or expected to vest | $	$ 108,192