Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2023	May 31, 2022
Accumulated other comprehensive income
Balance	$ 383,360	$ 353,274	$ 372,829	$ 344,324
Total other comprehensive income (loss)	1,408	(3,116)	4,505	(5,115)
Balance	397,569	366,565	397,569	366,565
Accumulated Other Comprehensive Income (loss)
Accumulated other comprehensive income
Balance	(17,270)	(13,209)	(20,367)	(11,210)
Other comprehensive gains (losses) before reclassifications			4,142	(5,387)
Reclassifications to net income of previously deferred (gains) losses			363	272
Total other comprehensive income (loss)			4,505	(5,115)
Balance	(15,862)	(16,325)	(15,862)	(16,325)
Gains on Restricted Investments:
Accumulated other comprehensive income
Balance			164	518
Other comprehensive gains (losses) before reclassifications			78	(213)
Reclassifications to net income of previously deferred (gains) losses			(74)	(64)
Total other comprehensive income (loss)			4	(277)
Balance	168	241	168	241
Restricted investments, other comprehensive gains (losses) before reclassifications, tax expense			28	70
Restricted investments, reclassifications to net income of previously deferred (gains) losses, tax (expense) benefit			26	22
Loss on Funded Pension Plan adjustments:
Accumulated other comprehensive income
Balance			(7,200)	(7,979)
Reclassifications to net income of previously deferred (gains) losses			437	336
Total other comprehensive income (loss)			437	336
Balance	(6,763)	(7,643)	(6,763)	(7,643)
Change in funded status of pension plan, other comprehensive gains (losses) before reclassifications, tax (expense) benefit			0	0
Change in funded status of pension plan, reclassifications to net income of previously deferred (gains) losses, tax (expense) benefit			145	111
Foreign Currency Translation Adjustment
Accumulated other comprehensive income
Balance			(13,331)	(3,749)
Other comprehensive gains (losses) before reclassifications			4,064	(5,174)
Total other comprehensive income (loss)			4,064	(5,174)
Balance	$ (9,267)	$ (8,923)	(9,267)	(8,923)
Foreign currency translation adjustment, other comprehensive gains (losses) before reclassifications, tax (expense) benefit			0	0
Foreign currency translation adjustment, reclassifications to net income of previously deferred (gains) losses, tax (expense) benefit			$ 0	$ 0