Note 7 - Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value of Senior Notes (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Euro Senior Notes, Series A [Member] | Reported Value Measurement [Member]
Senior Notes, Fair Value	$ 139,623	$ 122,313
Euro Senior Notes, Series A [Member] | Estimate of Fair Value Measurement [Member]
Senior Notes, Fair Value	138,294	122,586
Euro Senior Notes, Series B [Member] | Reported Value Measurement [Member]
Senior Notes, Fair Value	113,369	95,314
Euro Senior Notes, Series B [Member] | Estimate of Fair Value Measurement [Member]
Senior Notes, Fair Value	111,579	99,230
US Senior Notes A Due 2022 [Member] | Reported Value Measurement [Member]
Senior Notes, Fair Value	25,000	25,000
US Senior Notes A Due 2022 [Member] | Estimate of Fair Value Measurement [Member]
Senior Notes, Fair Value	24,737	24,746
US Senior Notes B Due 2027 [Member] | Reported Value Measurement [Member]
Senior Notes, Fair Value	100,000	100,000
US Senior Notes B Due 2027 [Member] | Estimate of Fair Value Measurement [Member]
Senior Notes, Fair Value	$ 99,992	$ 98,660