Note 12 - Segment Reporting - Income From Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income from operations	$ 19,573	$ 21,984	$ 39,021	$ 43,712
Operating Segments [Member] | United States Segment [Member]
Income from operations	27,948	29,256	54,258	58,099
Operating Segments [Member] | Europe Segment [Member]
Income from operations	3,756	4,009	7,977	7,371
Operating Segments [Member] | Corporate Unallocated and Japan Segment[Member]
Income from operations	(12,131)	(11,281)	(23,214)	(21,758)
Corporate and Reconciling Items [Member]
Income from operations	$ 19,573	$ 21,984	$ 39,021	$ 43,712