Note 4 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Business Combination, Contingent Consideration, Liability, Noncurrent	$ 17,500		$ 17,500		$ 14,200
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	$ 700	$ 600	$ 3,300	$ 1,400