Pension and Post-retirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Pension Plan
Pension Plan and Retirement Benefits
Service cost	$ 1,182	$ 1,407	$ 2,364	$ 2,814
Interest cost	1,923	1,808	3,846	3,616
Expected return	(3,561)	(3,978)	(7,122)	(7,956)
Amortizations	51	1,956	102	3,912
Net periodic benefit cost	(405)	1,193	(810)	2,386
Contribution to plan			3,000
Expected future employer contribution	3,000		3,000
Defined Benefit Other Postretirement Benefit Plan
Pension Plan and Retirement Benefits
Service cost	456	274	912	548
Interest cost	559	573	1,118	1,146
Amortizations	(60)		(120)
Net periodic benefit cost	955	$ 847	1,910	$ 1,694
Contribution to plan			1,362
Expected future employer contribution	$ 2,097		$ 2,097