Interim Pension and Other Postretirement Benefit Plan Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Contribution to postretirement medical plans	$ 3,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,908	$ 4,323
Interest cost	7,325	5,063
Expected return on assets	(7,278)	(7,383)
Amortization of prior service cost (credit)	(30)	(58)
Amortization of actuarial (gain) loss	164	1,951
Net periodic pension cost	3,089	3,896
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,546	2,559
Interest cost	3,478	2,683
Expected return on assets	(2,804)	(3,312)
Amortization of prior service cost (credit)	(3,285)	(3,309)
Amortization of actuarial (gain) loss	(1,863)	0
Net periodic pension cost	(2,928)	$ (1,379)
Minimum | Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions	15,000
Maximum | Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected future contributions	$ 25,000