v2.4.0.6
GOODWILL AND INTANGIBLE ASSETS (Details2) (USD $)
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period $ 989,493,000 $ 967,735,000  
Additions 397,423,000 44,698,000  
(Deductions) (409,000) (923,000)  
Impairment   (28,032,000) (916,868,000)
Foreign Exchange Translation (27,983,000) 6,015,000  
Balance at the end of the period 1,358,524,000 989,493,000 967,735,000
Search & Applications
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 526,681,000 527,604,000  
(Deductions) (237,000) (923,000)  
Impairment     (916,868,000)
Balance at the end of the period 526,444,000 526,681,000 527,604,000
IAC Search & Media
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 526,681,000 527,604,000  
(Deductions) (237,000) (923,000)  
Impairment     (916,900,000)
Balance at the end of the period 526,444,000 526,681,000 527,604,000
Goodwill accumulated impairment losses 916,900,000 916,900,000 916,900,000
Match
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 297,974,000 253,812,000  
Additions 397,115,000 37,375,000  
Foreign Exchange Translation (28,016,000) 6,787,000  
Balance at the end of the period 667,073,000 297,974,000  
Local
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 127,367,000 128,139,000  
Additions 301,000    
(Deductions) (3,000)    
Foreign Exchange Translation 33,000 (772,000)  
Balance at the end of the period 127,698,000 127,367,000  
HomeAdvisor
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 109,917,000 110,689,000  
(Deductions) (3,000)    
Foreign Exchange Translation 33,000 (772,000)  
Balance at the end of the period 109,947,000 109,917,000  
CityGrid Media
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 17,450,000    
Additions 301,000    
Balance at the end of the period 17,751,000   17,450,000
Media
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 15,759,000 8,436,000  
Additions   7,323,000  
(Deductions) (169,000)    
Balance at the end of the period 15,590,000 15,759,000  
Connected Ventures
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 8,436,000    
(Deductions) (169,000)    
Balance at the end of the period 8,267,000   8,436,000
Goodwill accumulated impairment losses 11,600,000 11,600,000 11,600,000
DailyBurn
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Additions   7,323,000  
Balance at the end of the period 7,323,000 7,323,000  
Other
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 21,712,000 49,774,000  
Additions 7,000    
Impairment   (28,032,000)  
Balance at the end of the period 21,719,000 21,712,000  
Shoebuy
      
Balance of goodwill by reporting unit, including the changes in the carrying value of goodwill      
Balance at the beginning of the period 21,712,000 49,744,000  
Additions 7,000    
Impairment   (28,032,000)  
Balance at the end of the period 21,719,000 21,712,000  
Goodwill accumulated impairment losses $ 28,000,000 $ 28,000,000