Accumulated Other Comprehensive Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Accumulated other comprehensive income
Selling, general and administrative expenses	$ (13,810)	$ (13,086)	$ (27,450)	$ (26,448)
Amortization of prior pension service costs and unrecognized losses	1	1	2	2
Settlement and curtailment loss		(273)		(473)
Tax expense (benefit)	(2,926)	(1,659)	(5,635)	(4,644)
Net income (loss)	7,879	5,273	15,241	14,096
Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Net income (loss)	111	281	238	530
Restricted investments | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Selling, general and administrative expenses	(23)	(13)	(28)	4
Tax expense (benefit)	6	3	7	(1)
Net income (loss)	(17)	(10)	(21)	3
Change in funded status of pension plans | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Tax expense (benefit)	(47)	(101)	(91)	(184)
Net income (loss)	128	291	259	527
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	119	$ 350	238
Settlement and curtailment loss		$ 273		$ 473