Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended			12 Months Ended			3 Months Ended	12 Months Ended				1 Months Ended		12 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Mar. 31, 2002	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010	Sep. 30, 2012 Online	Dec. 31, 2012 Online	Dec. 31, 2012 Software Development Costs	Dec. 31, 2011 Software Development Costs	Dec. 31, 2010 Software Development Costs	Oct. 31, 2011 Estimated remaining useful life for tangible assets Software Development Costs MediaMind Technologies ("Mediamind")	Oct. 31, 2011 Estimated remaining useful life for tangible assets Software Development Costs Previously reported MediaMind Technologies ("Mediamind")	Dec. 31, 2012 Estimated remaining useful life for tangible assets Software Development Costs Adjustment Impact MediaMind Technologies ("Mediamind")	Dec. 31, 2011 Estimated remaining useful life for tangible assets Software Development Costs Adjustment Impact MediaMind Technologies ("Mediamind")	Dec. 31, 2010 Estimated remaining useful life for tangible assets Certain developed technology	Dec. 31, 2010 Estimated remaining useful life for tangible assets Certain developed technology Previously reported	Dec. 31, 2010 Estimated remaining useful life for tangible assets Certain developed technology Adjustment Impact	Dec. 31, 2011 Reduction in estimate of Match Point's 2011 and 2012 revenues Adjustment Impact Match Point	Dec. 31, 2012 Reduction in estimated bonus
Change in estimates
Additional depreciation expense				$ 27,609,000	$ 18,580,000	$ 17,404,000			$ 8,500,000	$ 5,600,000	$ 7,500,000			$ 900,000	$ 500,000			$ 1,300,000
Increase (decrease) in net income (loss)														(500,000)	(300,000)			(700,000)	400,000	600,000
Increase (decrease) in diluted earnings (loss) per share														$ (0.02)	$ (0.01)			$ (0.03)	$ 0.02	$ 0.02
Estimated useful life									3 years			9 months	25 months			6 months	13 months
Reduction in estimated earnout obligation																			900,000
Net book value	66,169,000			66,169,000	54,159,000				16,100,000	12,200,000
Reduction in estimated bonus																				1,100,000
Increase (decrease) in income from continuing operations														(500,000)	(300,000)			(700,000)	400,000	600,000
Goodwill impairment	11,427,000	208,166,000	131,300,000	219,593,000			11,400,000	219,593,000
Long-Term Investments
Number of investments written down				2
Write-down of investments				$ 2,394,000