Note 11 - Treasury Stock and Repurchase Program - Schedule of Treasury Stock, at Cost (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended
		May 31, 2017		Jul. 31, 2017	Jul. 31, 2016	Apr. 30, 2017	[1],[2]
Balance, shares (in shares)	[1],[2]	288,335		288,335
Balance, total average cost assigned	[1],[2]	$ 3,781		$ 3,781
Balance, average cost per share (in dollars per share)	[1],[2]	$ 13.11		$ 13.11
Treasury Stock, Value, Acquired, Cost Method		$ 40	[2]	$ 40	$ 535
Purchases effected in open market, average cost per share (in dollars per share)	[2]	$ 17.29
Balance, average cost per share (in dollars per share)				$ 13.15
Balance, aggregate purchase price remaining under the program		$ 569	[2]	$ 569		$ 609
Treasury Stock, Shares, Acquired	[2]	2,353
Balance, shares (in shares)				290,688
Balance, total average cost assigned				$ 3,821

[1] Includes 85,219 shares with a total average cost of $1,036,000 that were acquired during the former repurchase program, which was authorized in January 2011 and expired in January 2012; 18,400 shares were acquired prior to January 2011.

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