Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2024	May 31, 2023	May 31, 2024	May 31, 2023
Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	$ 9,348	$ 9,645	$ 28,044	$ 28,934
Interest cost	8,982	7,647	26,946	22,941
Expected return on assets	(11,965)	(10,782)	(35,895)	(32,347)
Prior service cost (credit) amortization	45	37	134	112
Actuarial loss (gain) amortization	449	468	1,347	1,404
Net periodic benefit cost (benefit)	6,859	7,015	20,576	21,044
Non-Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	492	460	1,476	1,380
Interest cost	261	185	783	556
Expected return on assets	0	0	0	0
Prior service cost (credit) amortization	(29)	(29)	(86)	(86)
Actuarial loss (gain) amortization	95	61	285	184
Net periodic benefit cost (benefit)	819	677	2,458	2,034
Other Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	163	168	488	503
Interest cost	286	259	858	776
Expected return on assets	0	0	0	0
Prior service cost (credit) amortization	(111)	(111)	(334)	(334)
Actuarial loss (gain) amortization	(404)	(404)	(1,212)	(1,211)
Net periodic benefit cost (benefit)	$ (66)	$ (88)	$ (200)	$ (266)