Note 6 - Goodwill and Intangible Assets (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amortization of Intangible Assets	$ 610,000	$ 654,000	$ 995,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	662,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	374,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	318,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	180,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 39,000