SIGNIFICANT CUSTOMERS AND EXPORT SALES (Product Sales) (Details) (Sales Revenue, Goods, Net [Member])	12 Months Ended
	Dec. 31, 2011 ProductFamily	Dec. 31, 2010 ProductFamily	Dec. 31, 2009 ProductFamily
Product Concentration Risk [Member]
Revenue from External Customer [Line Items]
Number of primary groupings of low-power AC-DC power-conversion products	3	3	3
Product Concentration Risk [Member] | LinkSwitch [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	42.00%	37.00%	33.00%
Product Concentration Risk [Member] | TinySwitch [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	33.00%	38.00%	43.00%
Product Concentration Risk [Member] | TOPSwitch [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	23.00%	24.00%	23.00%
Product Concentration Risk [Member] | Other Product Families [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	2.00%	1.00%	1.00%
Product Concentration Risk [Member] | Minimum [Member] | Primary Low Power AC DC Power Conversion Products [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	98.00%	98.00%	98.00%
Product Concentration Risk [Member] | Minimum [Member] | Other Product Families [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	1.00%	1.00%	1.00%
Product Concentration Risk [Member] | Maximum [Member] | Primary Low Power AC DC Power Conversion Products [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	99.00%	99.00%	99.00%
Product Concentration Risk [Member] | Maximum [Member] | Other Product Families [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	2.00%	2.00%	2.00%
End Market Concentration Risk [Member] | Consumer Market [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	38.00%	38.00%	35.00%
End Market Concentration Risk [Member] | Communications Market [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	28.00%	31.00%	34.00%
End Market Concentration Risk [Member] | Industrial Electronics Market [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	22.00%	19.00%	17.00%
End Market Concentration Risk [Member] | Computer Market [Member]
Revenue from External Customer [Line Items]
Concentration risk percentage of net revenue	12.00%	12.00%	14.00%