Note 6 - Share Repurchase Program (Details Textual) $ in Thousands		3 Months Ended		6 Months Ended		9 Months Ended
	Jul. 07, 2017	Mar. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Nov. 04, 2015 USD ($) shares	Dec. 31, 2007 shares
Stock Repurchase Program, Authorized Amount | $							$ 40,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased | shares							2,000,000	1,000,000
Stock Repurchased and Retired During Period, Value | $		$ 7,500	$ 16,200	$ 0	$ 7,513	$ 0
Stock Repurchased and Retired During Period, Shares | shares		759,302	1,600,000
Stock Split from [Member] | Subsequent Event [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	5
Stock Split To [Member] | Subsequent Event [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	3