Stock-Based Compensation - Summary of RSUs Activity (Detail) - Restricted Stock Units (RSUs)	9 Months Ended
	Jun. 30, 2022 $ / shares shares
Number of RSUs
Beginning of period (in shares) | shares	3,831,850
Granted (in shares) | shares	1,691,367
Vested (in shares) | shares	(962,188)
Forfeited (in shares) | shares	(95,625)
End of period (in shares) | shares	4,465,404
Weighted- Average Grant Date Fair Value Per Share
Beginning balance (in dollars per share) | $ / shares	$ 61.24
Granted (in dollars per share) | $ / shares	56.73
Vested (in dollars per share) | $ / shares	49.10
Forfeited (in dollars per share) | $ / shares	69.32
Ending balance (in dollars per share) | $ / shares	$ 61.97