Supplementary Balance Sheet Information - Valuation Allowance for Deferred Tax Assets Activity (Details) - Valuation Allowance, Deferred Tax Asset - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 5,927	$ 8,592	$ 10,623
Charge to income tax provision (benefit)	1,137	1,337	(3,247)
Charged to other accounts	1,284	(4,002)	1,216
Balance at end of period	$ 8,348	$ 5,927	$ 8,592