Stockholders Equity - Share Repurchase Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Jul. 28, 2021
Stockholder's Equity
Repurchases of common stock from share repurchase plan		142,392	112,978
Repurchases of common stock to satisfy employee payroll taxes	17,708	37,002	23,751
Aggregate purchase price of shares repurchased to satisfy employee payroll taxes	$ 934
Share Repurchase Plan
Stockholder's Equity
Available cash to purchase shares				$ 20,000
Repurchases of common stock from share repurchase plan		142,392	112,978
Repurchase of common stock price (dollars per share)		$ 40.09	$ 37.57
Aggregate purchase price of shares repurchased from share repurchase plan		$ 5,709	$ 4,245