Note 11 - Treasury Stock and Repurchase Program (Details Textual) - USD ($)		1 Months Ended				3 Months Ended
		May 31, 2017		Jan. 30, 2012	Jan. 31, 2011	Jul. 31, 2017	Jul. 31, 2016	Sep. 19, 2012
Treasury Stock, Value, Acquired, Cost Method		$ 40,000	[1]			$ 40,000	$ 535,000
Treasury Stock, Shares, Acquired	[1]	2,353
September 2012 Share Repurchase Program [Member]
Stock Repurchase Program, Authorized Amount								$ 3,000,000
Former Repurchase Program [Member]
Treasury Stock, Value, Acquired, Cost Method				$ 1,036,000
Treasury Stock, Shares, Acquired				85,219
January 2011 Share Repurchase Program [Member]
Treasury Stock, Shares, Acquired					18,400

[1] Were acquired during the $3 million repurchase program authorized in September 2012.