Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2023	Feb. 28, 2022	Feb. 28, 2023	Feb. 28, 2022
Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	$ 9,645	$ 11,569	$ 19,290	$ 23,138
Interest cost	7,647	4,292	15,294	8,584
Expected return on assets	(10,782)	(10,990)	(21,565)	(21,979)
Prior service cost (credit) amortization	37	44	75	87
Actuarial loss (gain) amortization	468	5,852	936	11,703
Net periodic benefit cost (benefit)	7,015	10,767	14,030	21,533
Non-Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	460	232	920	463
Interest cost	185	70	371	141
Expected return on assets	0	0	0	0
Prior service cost (credit) amortization	(29)	(29)	(57)	(57)
Actuarial loss (gain) amortization	61	120	123	239
Net periodic benefit cost (benefit)	677	393	1,357	786
Other Benefits
Component of net periodic benefit costs: [Abstract]
Service cost	168	249	335	498
Interest cost	259	126	518	252
Expected return on assets	0	0	0	0
Prior service cost (credit) amortization	(111)	(111)	(223)	(223)
Actuarial loss (gain) amortization	(404)	(315)	(808)	(630)
Net periodic benefit cost (benefit)	$ (88)	$ (51)	$ (178)	$ (103)