Interim Pension and Other Postretirement Benefit Plan Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2,580	$ 2,837
Interest cost	6,925	6,663
Expected return on assets	(7,949)	(7,655)
Amortization of prior service cost (credit)	0	0
Amortization of actuarial (gain) loss	(51)	256
Net periodic pension cost	1,505	2,101
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2,017	2,033
Interest cost	3,635	3,365
Expected return on assets	(4,070)	(3,831)
Amortization of prior service cost (credit)	(2,880)	(3,260)
Amortization of actuarial (gain) loss	(2,415)	(2,429)
Net periodic pension cost	$ (3,713)	$ (4,122)