Stock-based Compensation Plans - Schedule of Stock Option Activity (Detail) - $ / shares	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options Outstanding, Beginning balance	922,000	940,000	871,000
Number of Options, Granted	342,000	274,000	299,000
Number of Options, Exercised	(45,000)	(248,000)	(125,000)
Number of Options, Forfeited and expired	(58,000)	(44,000)	(105,000)
Number of Options Outstanding, Ending balance	1,161,000	922,000	940,000
Number of Options, vested and exercisable	546,000
Weighted Average Exercise Price, Beginning Balance	$ 39.39	$ 35.18	$ 32.18
Weighted Average Exercise Price, Granted	42.10	40.95	41.06
Weighted Average Exercise Price, Exercised	21.24	24.22	22.89
Weighted Average Exercise Price, Forfeited and expired	43.99	44.58	41.69
Weighted Average Exercise Price, Ending balance	40.66	$ 39.39	$ 35.18
Weighted Average Exercise Price, vested and exercisable	$ 39.44