Goodwill and Other Intangible Assets - Summary of Changes in the Company's Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Goodwill and Intangible Assets Disclosure [Abstract]
Balance on beginning	$ 275,829	$ 262,103
Fiscal year business combinations	17,715	13,726
Other	(194)
Balance on ending	$ 293,350	$ 275,829