GOODWILL AND INTANGIBLE ASSETS Intangible Assets (Details) (USD $)	12 Months Ended											12 Months Ended		1 Months Ended		0 Months Ended	12 Months Ended		1 Months Ended		0 Months Ended	12 Months Ended		1 Months Ended		12 Months Ended		1 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Cost of revenue [Member]	Dec. 31, 2010 Cost of revenue [Member]	Dec. 31, 2009 Cost of revenue [Member]	Dec. 31, 2011 Operating expenses [Member]	Dec. 31, 2010 Operating expenses [Member]	Dec. 31, 2009 Operating expenses [Member]	Aug. 31, 2011 Dotomi Inc [Member]	Apr. 21, 2011 Greystripe Inc Acquisition [Member]	Dec. 31, 2011 Customer affiliate and advertiser relationships [Member] years	Dec. 31, 2010 Customer affiliate and advertiser relationships [Member]	Aug. 31, 2011 Customer affiliate and advertiser relationships [Member] Dotomi Inc [Member] years	Apr. 21, 2011 Customer affiliate and advertiser relationships [Member] Greystripe Inc Acquisition [Member] years	Aug. 03, 2010 Customer affiliate and advertiser relationships [Member] Investopedia Com Acquisition [Member] years	Dec. 31, 2011 Trademarks trade names and domain names [Member] years	Dec. 31, 2010 Trademarks trade names and domain names [Member]	Aug. 31, 2011 Trademarks trade names and domain names [Member] Dotomi Inc [Member] years	Apr. 21, 2011 Trademarks trade names and domain names [Member] Greystripe Inc Acquisition [Member] years	Aug. 03, 2010 Trademarks trade names and domain names [Member] Investopedia Com Acquisition [Member] years	Dec. 31, 2011 Developed technologies and websites [Member] years	Dec. 31, 2010 Developed technologies and websites [Member]	Aug. 31, 2011 Developed technologies and websites [Member] Dotomi Inc [Member] years	Apr. 21, 2011 Developed technologies and websites [Member] Greystripe Inc Acquisition [Member] years	Dec. 31, 2011 Covenants not to compete [Member] years	Dec. 31, 2010 Covenants not to compete [Member]	Aug. 31, 2011 Covenants not to compete [Member] Dotomi Inc [Member] years	Apr. 21, 2011 Covenants not to compete [Member] Greystripe Inc Acquisition [Member] years
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Useful Life												6		5	5	3	7		5	4	9	4		4	4	1		1	1.5
Gross Balance	$ 211,464,000	$ 120,037,000										$ 107,686,000	$ 48,327,000				$ 33,583,000	$ 29,811,000				$ 66,125,000	$ 34,399,000			$ 4,070,000	$ 7,500,000
Accumulated Amortization	(97,457,000)	(86,512,000)										(42,238,000)	(39,507,000)				(20,340,000)	(16,899,000)				(33,277,000)	(23,690,000)			(1,602,000)	(6,416,000)
Net Carrying Amount	114,007,000	33,525,000										65,448,000	8,820,000				13,243,000	12,912,000				32,848,000	10,709,000			2,468,000	1,084,000
Acquired Finite-lived Intangible Asset, Amount										82,460,000	24,300,000
Write-off of a fully amortized customer relationship asset												7,500,000														7,500,000
Recognized amortization expense on intangible assets	26,279,000	20,611,000	19,803,000	9,633,000	7,522,000	6,675,000	16,646,000	13,089,000	13,128,000
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2012	32,378,000			9,964,000			22,414,000
2013	24,857,000			9,343,000			15,514,000
2014	23,784,000			8,472,000			15,312,000
2015	20,013,000			4,760,000			15,253,000
2016	10,104,000			309,000			9,795,000
Thereafter	$ 2,871,000			$ 0			$ 2,871,000