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, 2016	$ 928	$ 14,719	$ (15,479)	$ 173,921	$ 174,089
Balance (in shares) at Aug. 31, 2016	9,278,486
Increase (Decrease) in Stockholders' Equity
Restricted stock grants, net of forfeitures	$ 4	(4)
Restricted stock grants, net of forfeitures (in shares)	44,567
Amortization of restricted stock grants		1,712			1,712
Amortization of stock option grants		500			500
Exercise of stock options	$ 8	1,245			1,253
Exercise of stock options (in shares)	80,168
Common stock received for payment of stock option exercises	$ (2)	(1,156)			(1,158)
Common stock received for payment of stock option exercises (in shares)	(15,079)
Common stock retained to pay statutory minimum withholding taxes on common stock	$ (3)	(2,956)			(2,959)
Common stock retained to pay statutory minimum withholding taxes on common stock (in shares)	(34,006)
Cash dividend on common stock				(6,532)	(6,532)
Change in funded status of pension plans, net of tax			1,155		1,155
Foreign currency translation adjustment			788		788
Net unrealized gain (loss) on restricted investments, net of tax			67		67
Net income				42,014	42,014
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 ASC 606				$ 22	$ 22