Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2015 USD ($)	Sep. 27, 2014 USD ($)	Oct. 03, 2015 USD ($) Segment	Sep. 27, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			5
Product Sales	$ 559,918	$ 637,148	$ 1,741,965	$ 1,879,268
Royalty Revenues	736	1,063	2,595	3,250
Total Revenue	560,654	638,211	1,744,560	1,882,518
Gross Margin	130,144	158,392	416,664	467,768
U.S. pension settlement charges	0	(15,588)	0	(15,588)
Segment Operating Income	(24,155)	45,459	67,573	145,954
Restructuring and severance Costs	(2,324)	(3,508)	(9,394)	(18,926)
Impairment of goodwill and long-lived assets	(62,980)	0	(62,980)	0
MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	109,446	121,631	322,553	358,715
Royalty Revenues	0	28	11	127
Total Revenue	109,446	121,659	322,564	358,842
Gross Margin	16,795	17,384	45,261	48,872
Diodes Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	123,922	151,444	399,155	437,944
Royalty Revenues	0	0	0	0
Total Revenue	123,922	151,444	399,155	437,944
Gross Margin	27,508	36,135	88,998	100,606
Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	70,008	67,549	211,610	188,305
Royalty Revenues	0	0	0	0
Total Revenue	70,008	67,549	211,610	188,305
Gross Margin	22,969	24,585	69,483	68,610
Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	172,995	189,419	538,173	569,944
Royalty Revenues	736	1,035	2,584	3,123
Total Revenue	173,731	190,454	540,757	573,067
Gross Margin	49,843	59,581	162,034	181,096
Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	83,547	107,105	270,474	324,360
Royalty Revenues	0	0	0	0
Total Revenue	83,547	107,105	270,474	324,360
Gross Margin	13,029	20,707	50,888	68,584
Operating Segments [Member] | MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	6,839	7,824	16,506	19,804
Operating Segments [Member] | Diodes Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	21,628	29,720	70,641	80,908
Operating Segments [Member] | Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	17,673	20,571	53,923	56,920
Operating Segments [Member] | Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	41,404	50,194	135,399	152,499
Operating Segments [Member] | Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	7,618	14,482	33,968	49,945
Unallocated Amount to Segment [Member]
Segment Reporting Information [Line Items]
U.S. pension settlement charges	0	(15,588)	0	(15,588)
Restructuring and severance Costs	(2,324)	(3,508)	(9,394)	(18,926)
Impairment of goodwill and long-lived assets	(62,980)	0	(62,980)	0
Unallocated Amount to Segment [Member] | Unallocated Amount to Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	$ (54,013)	$ (58,236)	$ (170,490)	$ (179,608)