Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Accounts receivable:
Allowance for doubtful accounts	$ 234	$ 227
Shareholders' equity:
Common stock, no par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	50,000,000	50,000,000
Common stock, shares issued (in shares)	36,693,000	36,461,000
Common stock, shares outstanding (in shares)	29,783,000	29,551,000
Treasury stock, shares held (in shares)	6,910,000	6,910,000