Other Comprehensive Income (Loss) (Reclassification Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income tax effect		$ (23,756)	$ (20,725)	$ (18,117)
Net of income tax expense (benefit)		89,501	78,162	73,681
Reclassification out of Accumulated Other Comprehensive Income
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(35,847)	(67,704)	(45,418)
Reclassification out of Accumulated Other Comprehensive Income | Defined Benefit Plan
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income tax effect		0	127	236
Net of income tax expense (benefit)		0	420	784
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	[1]	0	547	1,020
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income tax effect		(10,656)	(20,230)	(13,619)
Net of income tax expense (benefit)		(35,847)	(68,124)	(46,202)
Interest Rate Contract | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Interest (income) expense		$ (46,503)	$ (88,354)	$ (59,821)

[1] These items are included in the computation of net period pension cost. See Note 13. EMPLOYEE BENEFIT PLANS for additional disclosure