Pension and Post-retirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Pension Plan
Pension Plan and Retirement Benefits
Service cost	$ 672	$ 1,182	$ 2,016	$ 3,546
Interest cost	2,772	1,923	8,316	5,769
Expected return	(3,419)	(3,561)	(10,257)	(10,683)
Amortizations	52	51	154	153
Net periodic benefit cost	77	(405)	229	(1,215)
Contribution to plan			4,500
Expected future employer contribution	1,500		1,500
Defined Benefit Other Postretirement Benefit Plan
Pension Plan and Retirement Benefits
Service cost	348	456	1,042	1,368
Interest cost	799	559	2,399	1,677
Amortizations	(569)	(60)	(1,709)	(180)
Net periodic benefit cost	578	$ 955	1,732	$ 2,865
Contribution to plan			1,713
Expected future employer contribution	$ 1,563		$ 1,563