Note 4 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Business Combination, Contingent Consideration, Liability, Noncurrent			$ 16,800		$ 14,200
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	$ 700	$ 600	$ 2,600	$ 800