Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014 Segment	Jun. 29, 2013
Segment Reporting Information [Line Items]
Number of reportable segments			5
Product Sales	$ 641,080	$ 596,070	$ 1,242,120	$ 1,148,344
Royalty Revenues	849	1,595	2,187	3,575
Total Revenue	641,929	597,665	1,244,307	1,151,919
Gross Margin	164,093	142,857	309,376	279,591
Segment Operating Income	57,923	51,890	100,495	97,495
Operating Income (Loss)	57,923	51,890	100,495	97,495
Restructuring and severance Costs	(9,014)	0	(15,418)	0
MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	123,971	115,484	237,084	216,330
Royalty Revenues	71	79	99	121
Total Revenue	124,042	115,563	237,183	216,451
Gross Margin	18,871	16,466	31,488	29,366
Diodes Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	149,571	140,623	286,500	265,735
Royalty Revenues	0	0	0	0
Total Revenue	149,571	140,623	286,500	265,735
Gross Margin	34,706	31,427	64,471	58,688
Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	63,258	58,397	120,756	114,623
Royalty Revenues	0	0	0	0
Total Revenue	63,258	58,397	120,756	114,623
Gross Margin	22,788	19,151	44,025	38,925
Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	192,536	169,817	380,525	333,745
Royalty Revenues	778	1,516	2,088	3,454
Total Revenue	193,314	171,333	382,613	337,199
Gross Margin	61,395	54,345	121,515	106,946
Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	111,744	111,749	217,255	217,911
Royalty Revenues	0	0	0	0
Total Revenue	111,744	111,749	217,255	217,911
Gross Margin	26,333	21,468	47,877	45,666
Operating Segments [Member] | MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	9,493	5,682	11,980	8,515
Operating Segments [Member] | Diodes Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	28,130	25,339	51,188	46,728
Operating Segments [Member] | Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	18,945	15,558	36,349	31,767
Operating Segments [Member] | Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	51,969	45,540	102,305	89,740
Operating Segments [Member] | Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	20,122	15,585	35,463	34,041
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Executive compensation credit (charge)	0	1,778	0	1,778
Restructuring and severance Costs	(9,014)	0	(15,418)	0
Segment Reconciling Items [Member] | Unallocated Amount to Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	$ (61,722)	$ (57,592)	$ (121,372)	$ (115,074)