Stock-Based Compensation - Summarize Information about Stock Options (Detail)	12 Months Ended
	Sep. 30, 2021 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, beginning balance | shares	4,539,403
Number of Options Outstanding, Granted | shares	186,000
Number of Options Outstanding, Cancelled | shares	(217,820)
Number of Options Outstanding, Exercised | shares	(1,051,344)
Number of Options Outstanding, ending balance | shares	3,456,239
Number of Options Outstanding, Exercisable | shares	2,510,091
Weighted-Average Exercise Price Per Share, beginning balance | $ / shares	$ 16.67
Weighted-Average Exercise Price Per Share, Granted | $ / shares	65.57
Weighted-Average Exercise Price Per Share, Cancelled | $ / shares	40.12
Weighted-Average Exercise Price Per Share, Exercised | $ / shares	10.75
Weighted-Average Exercise Price Per Share, ending balance | $ / shares	19.60
Weighted-Average Exercise Price Per Share, Exercisable | $ / shares	$ 12.23
Weighted-Average Remaining Contractual Term	5 years 6 months 21 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 6 months 29 days
Aggregate Intrinsic Value | $	$ 149,501,055
Aggregate Intrinsic Value, Exercisable | $	$ 126,302,948