Note 4 - Fair Value Measurements - Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Business Combination, Contingent Consideration, Liability, Current	$ 9,339	$ 5,355
Fair Value, Measurements, Recurring [Member]
Business Combination, Contingent Consideration, Liability, Current	9,339
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Business Combination, Contingent Consideration, Liability, Current
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Business Combination, Contingent Consideration, Liability, Current
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Business Combination, Contingent Consideration, Liability, Current	$ 9,339