Goodwill and Intangible Assets (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended
Dec. 31, 2012
Sep. 30, 2012
Mar. 31, 2002
Dec. 31, 2012
item
Dec. 31, 2011
Dec. 31, 2011
MIJO Corporation ("MIJO")
Dec. 31, 2011
MediaMind Technologies ("Mediamind")
Dec. 31, 2012
Peer39, Inc
Dec. 31, 2011
EyeWonder LLC and Chors GmbH ("EyeWonder")
Dec. 31, 2012
North Country, Inc.
Dec. 31, 2011
Video and Audio Content Distribution
Dec. 31, 2012
Television
Dec. 31, 2011
Television
Dec. 31, 2011
Television
MIJO Corporation ("MIJO")
Dec. 31, 2012
Television
North Country, Inc.
Sep. 30, 2012
Online
Dec. 31, 2012
Online
Dec. 31, 2011
Online
Dec. 31, 2011
Online
MediaMind Technologies ("Mediamind")
Dec. 31, 2012
Online
Peer39, Inc
Dec. 31, 2011
Online
EyeWonder LLC and Chors GmbH ("EyeWonder")
Dec. 31, 2012
Source Ecreative
Dec. 31, 2011
Source Ecreative
Dec. 31, 2010
Source Ecreative
Goodwill and Other Long-Lived Assets                                                
Number of reportable units       3                                        
Number of reportable segments       2                                        
Changes in carrying value of goodwill by reporting unit                                                
Balance at the beginning of the period       $ 711,520 $ 357,548           $ 355,550 $ 363,068         $ 346,454         $ 1,998 $ 1,998 $ 1,998
Accumulated impairment losses       (131,291) (131,291)           (131,291) (131,291)                        
Balance at the beginning of the period       580,229 226,257           224,259 231,777         346,454         1,998 1,998 1,998
Purchase           19,524 292,117 7,225 43,437 823       19,524 823       292,117 7,225 43,437      
Goodwill impairment loss (11,427) (208,166) (131,300) (219,593)                       (11,400) (219,593)              
Foreign currency translation       453 (1,106)             453 (1,106)                      
Balance at the end of the period 720,021     720,021 711,520             364,344 363,068       353,679 346,454       1,998 1,998 1,998
Accumulated impairment losses (350,884)     (350,884) (131,291)             (131,291) (131,291)       (219,593)              
Balance at the end of the period 369,137     369,137 580,229             233,053 231,777       134,086 346,454       1,998 1,998 1,998
Reallocation of goodwill for change in segments                     $ (224,259)   $ 213,359         $ 10,900            
Number of significant acquisitions       2                                        
Excess percentage of fair value over carrying value                       13.00% 33.00%         6.00%       977.00%