Restructuring and Related Activities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 04, 2015	Jun. 28, 2014	Jul. 04, 2015	Jun. 28, 2014	Dec. 31, 2014	Dec. 31, 2013
Restructuring Reserve [Roll Forward]
Restructuring and severance costs	$ 5,660	$ 9,014	$ 7,070	$ 15,418
Expected Restructuring Costs	32,000		32,000
Global Cost Reduction Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Current	4,701		4,701
Restructuring Reserve [Roll Forward]
Restructuring and severance costs	$ 4,701	0	4,701	0
Cash paid			0
Term of restructuring program	30 months
Expected Restructuring Costs	$ 30,000		30,000
MOSFETs Enhanced Competitiveness Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Current	9,123		9,123
Restructuring Reserve [Roll Forward]
Restructuring and severance costs	939	1,492	2,292	3,219	$ 6,025	$ 2,328
Cash paid			(399)		(856)	(267)
Balance at end of period	$ 9,123		9,123		7,230	2,061
Balance at beginning of period			7,230	2,061	2,061
Term of restructuring program	2 years
Expected Restructuring Costs	$ 16,000		16,000
Voluntary Separation/Retirement Program [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Current	2,449		2,449
Restructuring Reserve [Roll Forward]
Restructuring and severance costs	20	7,522	77	12,199	12,792	486
Cash paid			(2,058)		(8,054)	(98)
Foreign currency translation			(244)		(455)	3
Balance at end of period	2,449		2,449		4,674	$ 391
Balance at beginning of period			4,674	391	391
Modules Product Transfer [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Current	821		821
Restructuring Reserve [Roll Forward]
Restructuring and severance costs	0	$ 0	0	$ 0	2,080
Cash paid			(563)		(464)
Foreign currency translation			(111)		(121)
Balance at end of period	$ 821		821		$ 1,495
Balance at beginning of period			$ 1,495