Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014 Segment	Sep. 28, 2013
Segment Reporting Information [Line Items]
Number of reportable segments			5
Product Sales	$ 637,148	$ 601,524	$ 1,879,268	$ 1,749,868
Royalty Revenues	1,063	1,366	3,250	4,941
Total Revenue	638,211	602,890	1,882,518	1,754,809
Gross Margin	158,392	143,220	467,768	422,811
U.S. pension settlement charges	(15,588)	0	(15,588)	0
Segment Operating Income	45,459	53,153	145,954	150,648
Operating Income (Loss)	45,459	53,153	145,954	150,648
Restructuring and severance Costs	(3,508)	0	(18,926)	0
MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	121,631	115,143	358,715	331,473
Royalty Revenues	28	25	127	146
Total Revenue	121,659	115,168	358,842	331,619
Gross Margin	17,384	15,735	48,872	45,101
Diodes Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	151,444	140,790	437,944	406,525
Royalty Revenues	0	0	0	0
Total Revenue	151,444	140,790	437,944	406,525
Gross Margin	36,135	32,405	100,606	91,093
Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	67,549	56,796	188,305	171,419
Royalty Revenues	0	51	0	51
Total Revenue	67,549	56,847	188,305	171,470
Gross Margin	24,585	20,163	68,610	59,088
Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	189,419	176,885	569,944	510,630
Royalty Revenues	1,035	1,290	3,123	4,744
Total Revenue	190,454	178,175	573,067	515,374
Gross Margin	59,581	54,093	181,096	161,039
Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Product Sales	107,105	111,910	324,360	329,821
Royalty Revenues	0	0	0	0
Total Revenue	107,105	111,910	324,360	329,821
Gross Margin	20,707	20,824	68,584	66,490
Operating Segments [Member] | MOSFETS Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	7,824	5,313	19,804	13,828
Operating Segments [Member] | Diodes Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	29,720	26,240	80,908	72,968
Operating Segments [Member] | Optoelectronic Components Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	20,571	16,492	56,920	48,259
Operating Segments [Member] | Resistors And Inductors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	50,194	45,096	152,499	134,836
Operating Segments [Member] | Capacitors Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	14,482	14,879	49,945	48,920
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
U.S. pension settlement charges	(15,588)	0	(15,588)	0
Executive compensation credit (charge)	0	0	0	1,778
Restructuring and severance Costs	(3,508)	0	(18,926)	0
Segment Reconciling Items [Member] | Unallocated Amount to Segment [Member]
Segment Reporting Information [Line Items]
Segment Operating Income	$ (58,236)	$ (54,867)	$ (179,608)	$ (169,941)