CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
CONSOLIDATED BALANCE SHEETS
Allowance for Doubtful Accounts Receivable, Current	$ 3,588	$ 3,445
Less accumulated depreciation and amortization	150,818	147,551
Accumulated amortization	$ 156,359	$ 149,892
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	50,000,000	50,000,000
Common stock, shares issued	30,705,913	30,666,173
Treasury stock, shares	4,720,417	4,604,741