Equity method investments Comparison of Carrying Value of Investmetn and Underlying Equity in Net Assets of Investment (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 140,615	$ 114,738
Japan JV
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	13,886	10,789
Equity Method Investment, Underlying Equity in Net Assets	35,045	34,312
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	(21,159)	(23,523)
South Korea JV
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	127,225	104,253
Equity Method Investment, Underlying Equity in Net Assets	133,161	109,992
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ (5,936)	$ (5,739)