Pre-Production Costs Related to Long-Term Supply Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014	Dec. 28, 2014
Unamortized Preproduction Costs [Abstract]
Preproduction costs	$ 69,683		$ 69,683		$ 65,621
Accumulated amortization	(56,284)		(56,284)		(53,408)
Net preproduction costs	13,399		13,399		12,213
Deferred Revenue [Abstract]
Accrued expenses	3,865		3,865		4,833
Other non-current liabilities	1,954		1,954		2,449
Total deferred tooling revenues	5,819		5,819		$ 7,282
Deferred Revenue, Revenue Recognized	$ 1,500	$ 2,100	$ 3,200	$ 4,100