Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Components of net periodic pension cost (benefit)
Service cost	$ 162	$ 164	$ 320	$ 329
Interest cost	1,346	1,507	2,679	3,038
Expected return on plan assets	(2,686)	(2,946)	(5,335)	(5,892)
Amortization of actuarial loss	1,165	968	2,305	1,969
Administrative expenses	89	83	178	169
Net pension cost (benefit)	$ 76	$ (224)	$ 147	$ (387)