Note 7 - Share Repurchase Program (Details Textual) $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 07, 2017	Mar. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2018 USD ($)	Aug. 15, 2017 shares	Nov. 04, 2015 USD ($) shares	Dec. 31, 2007 shares
Stock Repurchase Program, Number of Shares Authorized to be Repurchased | shares		806,000			3,300,000	2,000,000	1,000,000
Stock Repurchase Program, Authorized Amount | $		$ 12,600				$ 40,000
Stock Repurchased and Retired During Period, Shares | shares		0	200,000
Stock Repurchased and Retired During Period, Value | $			$ 3,800	$ 3,756
Stock Split from [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	5
Stock Split To [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	3