Condensed Consolidated Balance Sheet Parenthetical - USD ($) $ in Thousands	Jan. 31, 2018	Jul. 31, 2017
Current Assets
Allowance for doubtful accounts	$ 901	$ 748
Other Assets
Accumulated amortization of trademarks and patents	251	238
Accumulated amortization of customer lists	5,070	4,601
Noncurrent Liabilities
Net unamortized debt issuance costs	$ 75	$ 89
Common Stock
Stockholder's Equity
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares issued	8,049,050	8,015,166
Treasury stock, common shares	2,910,592	2,907,370
Common Class B
Stockholder's Equity
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares issued	2,503,678	2,513,512
Treasury stock, common shares	324,741	324,741