Note 5 - Goodwill and Intangible Assets (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization of Intangible Assets	$ 510	$ 500	$ 1,023	$ 898
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	2,038		2,038
Finite-Lived Intangible Assets, Amortization Expense, Year Two	2,031		2,031
Finite-Lived Intangible Assets, Amortization Expense, Year Three	2,014		2,014
Finite-Lived Intangible Assets, Amortization Expense, Year Four	2,008		2,008
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 1,588		$ 1,588