CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
CONSOLIDATED BALANCE SHEETS
Accumulated depreciation	$ 144,642	$ 130,534
Accumulated amortization	$ 143,792	$ 129,063
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	30,665,868	30,645,625
Treasury stock, shares	4,604,741	4,607,911