Goodwill and Other Intangible Assets - Summary of Changes in the Company's Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Balance on beginning	$ 262,103	$ 254,110
Fiscal year business combinations	13,726	7,993
Balance on ending	$ 275,829	$ 262,103