Condensed Consolidated Balance Sheet Parenthetical - USD ($) $ in Thousands	Oct. 31, 2018	Jul. 31, 2018
Current Assets
Allowance for doubtful accounts	$ 815	$ 817
Other Assets
Accumulated amortization of trademarks and patents	276	267
Accumulated amortization of customer lists	5,729	5,540
Noncurrent Liabilities
Net unamortized debt issuance costs	$ 53	$ 60
Common Stock
Stockholder's Equity
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares issued	8,135,349	8,086,849
Treasury stock, common shares	2,920,737	2,914,092
Common Class B
Stockholder's Equity
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares issued	2,569,979	2,468,979
Treasury stock, common shares	324,741	324,741