Consolidated Statements of Stockholders Equity Statement - USD ($) $ in Thousands	Total	Common & Class B Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss	Noncontrolling Interest
Total, Beginning of Period at Jul. 31, 2017	$ 126,037	$ 1,053	$ 36,242	$ 154,735	$ (55,701)	$ (10,292)	$ 0
Common & Class B Stock, Beginning of Period (in shares) at Jul. 31, 2017		10,528,678
Treasury Stock, Beginning of Period (in shares) at Jul. 31, 2017					(3,232,111)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	5,539	$ 0	0	5,539	$ 0	0	0
Other comprehensive income	561	0	0	0	0	561	0
Reclassification upon adoption of accounting standard	0	0	0	2,264	0	(2,264)	0
Dividends declared	(4,676)	0	0	(4,676)	0	0	0
Purchases of treasury stock	(27)	0	0	0	$ (27)	0	0
Purchases of treasury stock (in shares)					(622)
Net issuance of stock under long-term incentive plans	241	$ 2	442	0	$ (203)	0	0
Net issuance of stock under long-term incentive plans (in shares)		25,050			(5,600)
Amortization of restricted stock	1,338	$ 0	1,338	0	$ 0	0	0
Total, End of Period at Apr. 30, 2018	129,013	$ 1,055	38,022	157,862	$ (55,931)	(11,995)	0
Common Stock & Class B Stock, End of Period (in shares) at Apr. 30, 2018		10,553,728
Treasury Stock, End of Period (in shares) at Apr. 30, 2018					(3,238,333)
Total, Beginning of Period at Jan. 31, 2018	126,262	$ 1,055	37,253	153,571	$ (55,813)	(9,804)	0
Common & Class B Stock, Beginning of Period (in shares) at Jan. 31, 2018		10,552,728
Treasury Stock, Beginning of Period (in shares) at Jan. 31, 2018					(3,235,333)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	3,585	$ 0	0	3,585	$ 0	0	0
Other comprehensive income	73	0	0	0	0	73	0
Reclassification upon adoption of accounting standard	0	0	0	2,264	0	(2,264)	0
Dividends declared	(1,558)	0	0	(1,558)	0	0	0
Purchases of treasury stock	0	0	0	0	$ 0	0	0
Purchases of treasury stock (in shares)					0
Net issuance of stock under long-term incentive plans	241	$ 0	359	0	$ (118)	0	0
Net issuance of stock under long-term incentive plans (in shares)		1,000			(3,000)
Amortization of restricted stock	410	$ 0	410	0	$ 0	0	0
Total, End of Period at Apr. 30, 2018	129,013	$ 1,055	38,022	157,862	$ (55,931)	(11,995)	0
Common Stock & Class B Stock, End of Period (in shares) at Apr. 30, 2018		10,553,728
Treasury Stock, End of Period (in shares) at Apr. 30, 2018					(3,238,333)
Total, Beginning of Period at Jul. 31, 2018	131,885	$ 1,056	38,473	158,935	$ (55,946)	(10,615)	(18)
Common & Class B Stock, Beginning of Period (in shares) at Jul. 31, 2018		10,555,828
Treasury Stock, Beginning of Period (in shares) at Jul. 31, 2018					(3,238,833)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	8,777	$ 0	0	8,812	$ 0	0	(35)
Other comprehensive income	430	0	0	0	0	430	0
Dividends declared	(5,029)	0	0	(5,029)	0	0	0
Purchases of treasury stock	(141)	0	0	0	$ (141)	0	0
Purchases of treasury stock (in shares)					(4,545)
Net issuance of stock under long-term incentive plans	(1)	$ 29	420	0	$ (450)	0	0
Net issuance of stock under long-term incentive plans (in shares)		297,600			(7,737)
Amortization of restricted stock	1,594	$ 0	1,594	0	$ 0	0	0
Total, End of Period at Apr. 30, 2019	137,515	$ 1,085	40,487	162,718	$ (56,537)	(10,185)	(53)
Common Stock & Class B Stock, End of Period (in shares) at Apr. 30, 2019		10,853,428
Treasury Stock, End of Period (in shares) at Apr. 30, 2019					(3,251,115)
Total, Beginning of Period at Jan. 31, 2019	132,764	$ 1,081	39,730	158,788	$ (56,480)	(10,360)	5
Common & Class B Stock, Beginning of Period (in shares) at Jan. 31, 2019		10,812,928
Treasury Stock, Beginning of Period (in shares) at Jan. 31, 2019					(3,249,728)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	5,561	$ 0	0	5,619	$ 0	0	(58)
Other comprehensive income	175	0	0	0	0	175	0
Dividends declared	(1,689)	0	0	(1,689)	0	0	0
Purchases of treasury stock	(6)	0	0	0	$ (6)	0	0
Purchases of treasury stock (in shares)					0
Net issuance of stock under long-term incentive plans	0	$ 4	47	0	$ (51)	0	0
Net issuance of stock under long-term incentive plans (in shares)		40,500			(1,387)
Amortization of restricted stock	710	$ 0	710	0	$ 0	0	0
Total, End of Period at Apr. 30, 2019	$ 137,515	$ 1,085	$ 40,487	$ 162,718	$ (56,537)	$ (10,185)	$ (53)
Common Stock & Class B Stock, End of Period (in shares) at Apr. 30, 2019		10,853,428
Treasury Stock, End of Period (in shares) at Apr. 30, 2019					(3,251,115)