Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified													3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Customer Relationships [Member]	Dec. 31, 2012 Customer Relationships [Member]	Mar. 31, 2013 Acquired technology [Member]	Dec. 31, 2012 Acquired technology [Member]	Mar. 31, 2013 Non-compete agreements [Member]	Dec. 31, 2012 Non-compete agreements [Member]	Mar. 31, 2013 Trademarks [Member]	Dec. 31, 2012 Trademarks [Member]	Mar. 31, 2013 Domain names [Member]	Dec. 31, 2012 Domain names [Member]	Mar. 31, 2013 Maximum [Member] Customer Relationships [Member]	Mar. 31, 2013 Maximum [Member] Acquired technology [Member]	Mar. 31, 2013 Maximum [Member] Non-compete agreements [Member]	Mar. 31, 2013 Minimum [Member] Customer Relationships [Member]	Mar. 31, 2013 Minimum [Member] Acquired technology [Member]	Mar. 31, 2013 Minimum [Member] Non-compete agreements [Member]
Schedule of components of intangible assets
Intangible assets useful life													15 years	15 years	6 years	7 years	8 years	3 years
Customer relationships, Gross Carrying Amount			$ 56,854	$ 57,040
Acquired technology, Gross Carrying Amount					50,876	51,067
Non-compete agreements, Gross Carrying Amount							11,980	12,016
Trademarks/Domain names, Gross Carrying Amount									35,383	35,537	4,400	4,400
Gross Carrying Amount	159,493	160,060
Accumulated Amortization	(75,818)	(73,324)	(37,858)	(36,464)	(26,220)	(25,108)	(11,740)	(11,752)
Net Balance, Finite-Lived Intangible Assets			18,996	20,576	24,656	25,959	240	264
Net Balance, Indefinite-Lived Intangible Assets									35,383	35,537	4,400	4,400
Net Balance	$ 83,675	$ 86,736