Accumulated Other Comprehensive Income - Reclassifications (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2022	Aug. 31, 2021	Aug. 31, 2020
Accumulated other comprehensive income
Selling, general and administrative expenses	$ (54,438)	$ (52,100)	$ (49,364)
Amortization of prior pension service costs and unrecognized losses	$ 3	$ 3	$ 3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Settlement and curtailment loss			$ (155)
Tax expense (benefit)	$ (13,927)	$ (13,674)	(11,163)
Net income (loss)	44,671	44,920	$ 34,157
Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Net income (loss)	377	449
Gains on Restricted Investments: | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Selling, general and administrative expenses	(96)	(65)
Tax expense (benefit)	24	17
Net income (loss)	(72)	(48)
Loss on Funded Pension Plan adjustments: | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Amortization of prior pension service costs and unrecognized losses	$ 596	$ 659
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Tax expense (benefit)	$ (147)	$ (162)
Net income (loss)	$ 449	$ 497