CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Total
Balance at Aug. 31, 2017	$ 935	$ 14,060	$ (13,469)	$ 209,403	$ 210,929
Balance (in shares) at Aug. 31, 2017	9,354,136
Increase (Decrease) in Stockholders' Equity
Restricted stock grants, net of forfeitures	$ 2	(2)
Restricted stock grants, net of forfeitures (in shares)	16,701
Amortization of restricted stock grants		1,669			1,669
Amortization of stock option grants		459			459
Exercise of stock options	$ 6	1,214			1,220
Exercise of stock options (in shares)	64,012
Common stock received for payment of stock option exercises	$ (1)	(1,027)			(1,028)
Common stock received for payment of stock option exercises (in shares)	(9,693)
Common stock retained to pay statutory minimum withholding taxes on common stock	$ (3)	(3,269)			(3,272)
Common stock retained to pay statutory minimum withholding taxes on common stock (in shares)	(28,209)
Cash dividend on common stock				(7,497)	(7,497)
Change in funded status of pension plans, net of tax			385		385
Foreign currency translation adjustment			743		743
Net unrealized gain (loss) on restricted investments, net of tax			5		5
Net income				43,143	43,143
Balance at Aug. 31, 2018	$ 939	13,104	(12,336)	245,049	246,756
Balance (in shares) at Aug. 31, 2018	9,396,947
Increase (Decrease) in Stockholders' Equity
Restricted stock grants, net of forfeitures	$ 1	(1)
Restricted stock grants, net of forfeitures (in shares)	8,818
Amortization of restricted stock grants		1,673			1,673
Amortization of stock option grants		503			503
Exercise of stock options	$ 1	300			301
Exercise of stock options (in shares)	7,022
Common stock received for payment of stock option exercises		(119)			(119)
Common stock received for payment of stock option exercises (in shares)	(954)
Common stock retained to pay statutory minimum withholding taxes on common stock	$ (1)	(1,109)			(1,110)
Common stock retained to pay statutory minimum withholding taxes on common stock (in shares)	(11,085)
Cash dividend on common stock				(7,522)	(7,522)
Change in funded status of pension plans, net of tax			(475)		(475)
Foreign currency translation adjustment			(1,541)		(1,541)
Net unrealized gain (loss) on restricted investments, net of tax			28		28
Net income				32,711	32,711
Balance at Aug. 31, 2019	$ 940	14,351	(14,324)	270,260	271,227
Balance (in shares) at Aug. 31, 2019	9,400,748
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standard | ASU 2014-09				22	22
Restricted stock grants, net of forfeitures	$ 5	(5)
Restricted stock grants, net of forfeitures (in shares)	45,621
Amortization of restricted stock grants		2,290			2,290
Amortization of stock option grants		918			918
Exercise of stock options		123			123
Exercise of stock options (in shares)	3,618
Common stock received for payment of stock option exercises		(123)			(123)
Common stock received for payment of stock option exercises (in shares)	(1,057)
Common stock retained to pay statutory minimum withholding taxes on common stock	$ (1)	(880)			(881)
Common stock retained to pay statutory minimum withholding taxes on common stock (in shares)	(9,848)
Cash dividend on common stock				(7,539)	(7,539)
Change in funded status of pension plans, net of tax			(658)		(658)
Foreign currency translation adjustment			3,163		3,163
Net unrealized gain (loss) on restricted investments, net of tax			115		115
Net income				34,157	34,157
Balance at Aug. 31, 2020	$ 944	$ 16,674	(13,092)	298,266	$ 302,792
Balance (in shares) at Aug. 31, 2020	9,439,082
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standard | ASU 2018-02			(1,388)	$ 1,388
Adoption of new accounting standard			$ (1,388)