Note 10 - Segment Information (Details Textual) $ in Thousands	3 Months Ended
	Apr. 01, 2017 USD ($)	Apr. 02, 2016 USD ($)
Number of Operating Segments	3
Operating Income (Loss)	$ 48,852	$ 32,428
Other Segments [Member]
Operating Income (Loss)	$ (1,525)	(9,152)
Other Segments [Member] | Operating Income (Loss) [Member]
Restructuring Charges		1,400
Other Segments [Member] | Operating Income (Loss) [Member] | DENMARK
Impairment and Severance Costs		1,600
Other Segments [Member] | Cost of Sales [Member]
Restructuring Charges		1,100
Other Segments [Member] | Cost of Sales [Member] | DENMARK
Impairment and Severance Costs		200
Other Segments [Member] | Selling, General and Administrative Expenses [Member]
Restructuring Charges		300
Business Combination, Acquisition Related Costs		6,200
Other Segments [Member] | Selling, General and Administrative Expenses [Member] | DENMARK
Impairment and Severance Costs		200
Other Segments [Member] | Amortization of Intangibles Assets [Member] | DENMARK
Impairment and Severance Costs		900
Other Segments [Member] | Research and Development Expense [Member] | DENMARK
Impairment and Severance Costs		$ 300