Accumulated Other Comprehensive Income - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended
	Nov. 30, 2019	Nov. 30, 2018
Accumulated other comprehensive income
Selling, general and administrative expenses	$ (13,640)	$ (13,362)
Amortization of prior pension service costs and unrecognized losses	1	1
Settlement and curtailment loss		(200)
Tax expense (benefit)	(2,709)	(2,985)
Net income (loss)	7,362	8,823
Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Net income (loss)	127	249
Restricted investments | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Selling, general and administrative expenses	(5)	17
Tax expense (benefit)	1	(4)
Net income (loss)	(4)	13
Change in funded status of pension plans | Reclassification out of accumulated other comprehensive income (loss)
Accumulated other comprehensive income
Tax expense (benefit)	(44)	(83)
Net income (loss)	131	236
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
Settlement and curtailment loss		$ 200