Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2024	Feb. 28, 2023	Feb. 29, 2024	Feb. 28, 2023
Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	$ 9,348	$ 9,645	$ 18,696	$ 19,290
Interest cost	8,982	7,647	17,964	15,294
Expected return on assets	(11,965)	(10,782)	(23,930)	(21,565)
Prior service cost (credit) amortization	45	37	89	75
Actuarial loss (gain) amortization	449	468	898	936
Net periodic benefit cost (benefit)	6,859	7,015	13,717	14,030
Non-Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	492	460	984	920
Interest cost	261	185	522	371
Expected return on assets	0	0	0	0
Prior service cost (credit) amortization	(29)	(29)	(57)	(57)
Actuarial loss (gain) amortization	95	61	190	123
Net periodic benefit cost (benefit)	819	677	1,639	1,357
Other Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	163	168	325	335
Interest cost	286	259	572	518
Expected return on assets	0	0	0	0
Prior service cost (credit) amortization	(111)	(111)	(223)	(223)
Actuarial loss (gain) amortization	(404)	(404)	(808)	(808)
Net periodic benefit cost (benefit)	$ (66)	$ (88)	$ (134)	$ (178)