Note 10 - Segment Information - Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2017	Dec. 31, 2017
NET SALES	$ 318,325	$ 257,431	$ 842,514	$ 730,233
Depreciation and amortization	9,877	7,782	27,067	22,203	$ 22,203
Assets	1,342,960		1,342,960			$ 800,600
Operating Segments [Member]
NET SALES	318,325	257,431	842,514	730,233
Depreciation and amortization	8,698	7,243	24,511	20,779
Assets	1,261,312		1,261,312
Americas [Member] | Operating Segments [Member]
NET SALES	182,660	148,082	494,265	433,461
Depreciation and amortization	3,373	3,386	10,464	10,064
Assets	472,473		472,473
Europe [Member] | Operating Segments [Member]
NET SALES	88,223	66,677	220,645	180,506
Depreciation and amortization	3,181	1,646	7,483	4,257
Assets	587,228		587,228
Asia Pacific [Member] | Operating Segments [Member]
NET SALES	47,442	42,672	127,604	116,266
Depreciation and amortization	2,144	$ 2,211	6,564	$ 6,458
Assets	$ 201,611		$ 201,611