Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Components of net periodic pension cost (benefit)
Service cost	$ 164	$ 150	$ 329	$ 299
Interest cost	1,507	1,921	3,038	3,831
Expected return on plan assets	(2,946)	(3,034)	(5,892)	(6,043)
Amortization of actuarial loss	968	534	1,969	1,062
Administrative expenses	83	97	169	194
Net pension cost (benefit)	$ (224)	$ (332)	$ (387)	$ (657)