Note 12 - Segment Reporting - Income From Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income from operations	$ 19,448	$ 21,728
Operating Segments [Member] | United States Segment [Member]
Income from operations	26,310	28,843
Operating Segments [Member] | Europe Segment [Member]
Income from operations	4,221	3,361
Corporate and Reconciling Items [Member] | Corporate Unallocated and Japan Segment[Member]
Income from operations	$ (11,083)	$ (10,476)