Valuation and Qualifying Accounts (Detail) - Allowance for Doubtful Accounts - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year		$ 4,779	$ 6,121	$ 8,378
Charged to Costs & Expenses		5,411	(248)	3,441
Other Changes Add (Deduct)	[1]	(2,435)	(1,094)	(5,698)
Balance at End of Year		$ 7,755	$ 4,779	$ 6,121

[1] Bad debts written off (net of recoveries).