Note 6 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Mar. 03, 2015
Maximum Aggregate Offering Price				$ 150,000
Stock Issued During Period, Shares, New Issues	6,061
Shares Issued, Price Per Share	$ 8.50	$ 8.50
Proceeds from Issuance of Common Stock	$ 47,750	$ 47,750