Accumulated Other Comprehensive Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Accumulated other comprehensive income
Selling, general and administrative expenses	$ (12,773)	$ (13,251)	$ (40,223)	$ (39,699)
Amortization of prior pension service costs and unrecognized losses	1	1	3	3
Settlement and curtailment loss	(75)	(11)	(75)	(484)
Tax expense (benefit)	(2,619)	(3,647)	(8,254)	(8,291)
Net income (loss)	9,908	8,541	25,149	22,637
Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Net income (loss)	182	87	420	617
Restricted investments | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Selling, general and administrative expenses	(4)	(6)	(32)	(2)
Tax expense (benefit)	1	2	8	1
Net income (loss)	(3)	(4)	(24)	(1)
Change in funded status of pension plans | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Tax expense (benefit)	(65)	(34)	(156)	(218)
Net income (loss)	185	91	444	618
Change in funded status of pension plans | Reclassification out of accumulated other comprehensive income (loss) | Other income (expense)
Accumulated other comprehensive income
Amortization of prior pension service costs and unrecognized losses	175	114	525	352
Settlement and curtailment loss	$ 75	$ 11	$ 75	$ 484