Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2015 USD ($)	Jun. 28, 2014 USD ($)	Jul. 04, 2015 USD ($) Segment	Jun. 28, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			5
Product Sales	$ 589,724	$ 641,080	$ 1,182,047	$ 1,242,120
Royalty Revenues	746	849	1,859	2,187
Total Revenue	590,470	641,929	1,183,906	1,244,307
Gross Margin	141,482	164,093	286,520	309,376
Segment Operating Income	44,170	57,923	91,728	100,495
Restructuring and severance Costs	(5,660)	(9,014)	(7,070)	(15,418)
MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	106,348	123,971	213,107	237,084
Royalty Revenues	0	71	11	99
Total Revenue	106,348	124,042	213,118	237,183
Gross Margin	14,708	18,871	28,466	31,488
Diodes Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	138,722	149,571	275,233	286,500
Royalty Revenues	0	0	0	0
Total Revenue	138,722	149,571	275,233	286,500
Gross Margin	31,600	34,706	61,490	64,471
Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	72,977	63,258	141,602	120,756
Royalty Revenues	0	0	0	0
Total Revenue	72,977	63,258	141,602	120,756
Gross Margin	24,331	22,788	46,514	44,025
Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	178,786	192,536	365,178	380,525
Royalty Revenues	746	778	1,848	2,088
Total Revenue	179,532	193,314	367,026	382,613
Gross Margin	53,342	61,395	112,191	121,515
Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	92,891	111,744	186,927	217,255
Royalty Revenues	0	0	0	0
Total Revenue	92,891	111,744	186,927	217,255
Gross Margin	17,501	26,333	37,859	47,877
Operating Segments [Member] | MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	5,140	9,493	9,667	11,980
Operating Segments [Member] | Diodes Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	25,528	28,130	49,013	51,188
Operating Segments [Member] | Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	19,163	18,945	36,250	36,349
Operating Segments [Member] | Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	44,470	51,969	93,995	102,305
Operating Segments [Member] | Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	11,786	20,122	26,350	35,463
Unallocated Amount to Segment [Member]
Segment Reporting Information [Line Items]
Restructuring and severance Costs	(5,660)	(9,014)	(7,070)	(15,418)
Unallocated Amount to Segment [Member] | Unallocated Amount to Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	$ (56,257)	$ (61,722)	$ (116,477)	$ (121,372)