Financial Instruments Measured at Fair Value - AFS (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 27, 2015	Dec. 31, 2014
Marubun [Member]
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Investment Ownership Percentage	8.40%
Cost basis	$ 10,016	$ 10,016
Unrealized holding gain	8,805	6,174
Fair value	18,821	16,190
Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost basis	16,617	16,233
Unrealized holding gain	7,376	5,686
Fair value	$ 23,993	$ 21,919