Note 1 - Basis of Presentation (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Jan. 01, 2017 USD ($)
Revenue, Net	$ 128,939	$ 106,456	$ 341,499	$ 285,047
US-based Distributors [Member]
Revenue, Net	2,200		5,900
Deferred Revenue, Current	$ 2,700		$ 2,700
US-based Distributors [Member]
Number of Distributors	3		3
Accounting Standards Update 2016-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 5,100