v3.26.3
Benefit Plans - Financial Information on Changes in Benefit Obligation, Plan Assets Funded and Balance Sheets Status (Details) - USD ($)
$ in Thousands
 12 Months Ended
Aug. 31, 2026
Aug. 31, 2025
Aug. 31, 2024
Change in plan assets:      
Fair value of plan assets at beginning of period $ 776,286    
Company contributions 40,000    
Fair value of plan assets at end of period 736,303 $ 776,286  
Other Benefits      
Change in benefit obligation:      
Projected benefit obligation at beginning of period 23,627 24,787  
Service cost 840 844 $ 650
Interest cost 1,125 1,140 1,144
Experience study, lump sum, and crediting rate updates 0 (29)  
Other demographic experience 1,041 (646)  
Discount rate change (1,049) (845)  
Plan amendments (2,423) 0  
Benefits paid (1,551) (1,624)  
Projected benefit obligation at end of period 21,610 23,627 24,787
Change in plan assets:      
Fair value of plan assets at beginning of period 0 0  
Actual (loss) gain on plan assets 0 0  
Company contributions 1,551 1,624  
Benefits paid (1,551) (1,624)  
Fair value of plan assets at end of period 0 0 0
Funded status at end of period (21,610) (23,627)  
Amounts recognized on balance sheet:      
Noncurrent assets 0 0  
Accrued benefit cost:      
Current liabilities (1,700) (1,630)  
Non-current liabilities (19,910) (21,997)  
Ending balance (21,610) (23,627)  
Amounts recognized in accumulated other comprehensive loss (pretax):      
Prior service cost (credit) (2,468) (490)  
Net loss (gain) (13,472) (14,662)  
Ending balance (15,940) (15,152)  
Qualified Pension Benefits | Pension Benefits      
Change in benefit obligation:      
Projected benefit obligation at beginning of period 773,522 760,763  
Service cost 45,390 43,727 37,391
Interest cost 36,106 34,898 35,928
Experience study, lump sum, and crediting rate updates 11,442 8,394  
Other demographic experience 4,556 20,025  
Discount rate change (33,590) (30,273)  
Plan amendments 357 (6,236)  
Benefits paid (105,520) (57,776)  
Projected benefit obligation at end of period 732,263 773,522 760,763
Change in plan assets:      
Fair value of plan assets at beginning of period 776,286 781,412  
Actual (loss) gain on plan assets 25,538 22,650  
Company contributions 40,000 30,000  
Benefits paid (105,520) (57,776)  
Fair value of plan assets at end of period 736,304 776,286 781,412
Funded status at end of period 4,041 2,764  
Amounts recognized on balance sheet:      
Noncurrent assets 12,688 11,969  
Accrued benefit cost:      
Current liabilities 0 0  
Non-current liabilities (8,647) (9,205)  
Ending balance 4,041 2,764  
Amounts recognized in accumulated other comprehensive loss (pretax):      
Prior service cost (credit) (4,267) (5,219)  
Net loss (gain) 269,467 278,779  
Ending balance 265,200 273,560  
Nonqualified Pension Benefits | Pension Benefits      
Change in benefit obligation:      
Projected benefit obligation at beginning of period 31,464 26,443  
Service cost 3,325 3,027 1,968
Interest cost 1,340 1,154 1,043
Experience study, lump sum, and crediting rate updates 382 365  
Other demographic experience (814) 2,862  
Discount rate change (956) (331)  
Plan amendments 0 (227)  
Benefits paid (1,999) (1,829)  
Projected benefit obligation at end of period 32,742 31,464 26,443
Change in plan assets:      
Fair value of plan assets at beginning of period 0 0  
Actual (loss) gain on plan assets 0 0  
Company contributions 1,999 1,829  
Benefits paid (1,999) (1,829)  
Fair value of plan assets at end of period 0 0 $ 0
Funded status at end of period (32,742) (31,464)  
Amounts recognized on balance sheet:      
Noncurrent assets 0 0  
Accrued benefit cost:      
Current liabilities (5,290) (4,890)  
Non-current liabilities (27,452) (26,574)  
Ending balance (32,742) (31,464)  
Amounts recognized in accumulated other comprehensive loss (pretax):      
Prior service cost (credit) (197) (227)  
Net loss (gain) 7,728 10,097  
Ending balance $ 7,531 $ 9,870