Note 1 - General (Details Textual) $ in Thousands		12 Months Ended
	Mar. 05, 2014 USD ($) shares	Dec. 31, 2016 shares	Dec. 31, 2015 shares	Mar. 13, 2014 shares
Operations Commenced Date		Jan. 01, 2005
Subsidiary or Equity Method Investee, Number		6
Entity Incorporation, Date of Incorporation		Nov. 24, 2004
Common Stock, Shares, Issued		26,821,762	26,069,154
Common Stock, Shares Issued upon Exercise by Underwriters	500,436
Proceeds from Issuance of Common Stock | $	$ 106,071
Conversion of Convertible Preferred Stock to Common Stock at Initial Public Offering, Shares	15,082,141
Conversion of Preferred Stock Warrants to Common Stock Warrants, Shares	122,572
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				107,217
IPO [Member]
Common Stock, Shares, Issued	5,300,436