Employee Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Retirement Benefits [Abstract]
Service cost	$ 1,156	$ 1,125	$ 898
Interest cost	482	492	699
Expected return on plan assets	(615)	(387)	(440)
Amortization of actuarial losses	1,042	1,006	371
Pension expense for defined benefit plans	$ 2,065	$ 2,236	$ 1,528