CONDENSED 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, 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)	9,308
Amortization of restricted stock grants		795			795
Amortization of stock option grants		249			249
Exercise of stock options	$ 1	301			302
Exercise of stock options (in shares)	7,022
Common stock received for payment of stock option exercises		(120)			(120)
Common stock received for payment of stock option exercises (in shares)	(954)
Cash dividend on common stock				(7,522)	(7,522)
Change in funded status of pension plans, net of tax			527		527
Foreign currency translation adjustment			538		538
Net unrealized gain (loss) on restricted investments, net of tax			(8)		(8)
Net income				14,096	14,096
Balance at Feb. 28, 2019	$ 941	14,328	(11,279)	251,645	255,635
Balance (in shares) at Feb. 28, 2019	9,412,323
Balance at Nov. 30, 2018	$ 940	13,608	(12,727)	246,372	248,193
Balance (in shares) at Nov. 30, 2018	9,402,706
Increase (Decrease) in Stockholders' Equity
Restricted stock grants, net of forfeitures (in shares)	4,599
Amortization of restricted stock grants		415			415
Amortization of stock option grants		124			124
Exercise of stock options	$ 1	181			182
Exercise of stock options (in shares)	5,018
Change in funded status of pension plans, net of tax			291		291
Foreign currency translation adjustment			1,144		1,144
Net unrealized gain (loss) on restricted investments, net of tax			13		13
Net income				5,273	5,273
Balance at Feb. 28, 2019	$ 941	14,328	(11,279)	251,645	255,635
Balance (in shares) at Feb. 28, 2019	9,412,323
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standard | ASU 2014-09				22	22
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
Restricted stock grants, net of forfeitures	$ 5	(5)
Restricted stock grants, net of forfeitures (in shares)	45,311
Amortization of restricted stock grants		1,080			1,080
Amortization of stock option grants		456			456
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)
Cash dividend on common stock				(7,539)	(7,539)
Change in funded status of pension plans, net of tax			259		259
Foreign currency translation adjustment			1,395		1,395
Net unrealized gain (loss) on restricted investments, net of tax			(2)		(2)
Net income				15,241	15,241
Balance at Feb. 29, 2020	$ 945	15,882	(14,060)	279,350	282,117
Balance (in shares) at Feb. 29, 2020	9,448,620
Balance at Nov. 30, 2019	$ 942	15,063	(14,003)	271,471	273,473
Balance (in shares) at Nov. 30, 2019	9,423,946
Increase (Decrease) in Stockholders' Equity
Restricted stock grants, net of forfeitures	$ 3	(3)
Restricted stock grants, net of forfeitures (in shares)	24,674
Amortization of restricted stock grants		594			594
Amortization of stock option grants		228			228
Change in funded status of pension plans, net of tax			128		128
Foreign currency translation adjustment			(142)		(142)
Net unrealized gain (loss) on restricted investments, net of tax			(43)		(43)
Net income				7,879	7,879
Balance at Feb. 29, 2020	$ 945	$ 15,882	(14,060)	279,350	$ 282,117
Balance (in shares) at Feb. 29, 2020	9,448,620
Increase (Decrease) in Stockholders' Equity
Adoption of new accounting standard | ASU 2018-02			(1,388)	$ 1,388
Adoption of new accounting standard			$ (1,388)