Intangible Assets - Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified					6 Months Ended				6 Months Ended				6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Customer Relationships [Member]	Dec. 31, 2012 Customer Relationships [Member]	Jun. 30, 2013 Customer Relationships [Member] Minimum [Member]	Jun. 30, 2013 Customer Relationships [Member] Maximum [Member]	Jun. 30, 2013 Acquired Technology [Member]	Dec. 31, 2012 Acquired Technology [Member]	Jun. 30, 2013 Acquired Technology [Member] Minimum [Member]	Jun. 30, 2013 Acquired Technology [Member] Maximum [Member]	Jun. 30, 2013 Non-compete Agreements [Member]	Dec. 31, 2012 Non-compete Agreements [Member]	Jun. 30, 2013 Non-compete Agreements [Member] Minimum [Member]	Jun. 30, 2013 Non-compete Agreements [Member] Maximum [Member]	Jun. 30, 2013 Trademarks [Member]	Dec. 31, 2012 Trademarks [Member]	Jun. 30, 2013 Domain Names [Member]	Dec. 31, 2012 Domain Names [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets useful life					7 years	15 years			8 years	15 years			3 years	6 years
Customer relationships, Gross Carrying Amount			$ 56,925	$ 57,040
Acquired technology, Gross Carrying Amount							50,901	51,067
Non-compete agreements, Gross Carrying Amount											11,997	12,016
Trademarks/Domain names, Gross Carrying Amount															35,452	35,537	4,400	4,400
Gross Carrying Amount	159,675	160,060
Accumulated Amortization	(78,502)	(73,324)	(39,353)	(36,464)			(27,371)	(25,108)			(11,778)	(11,752)
Net Balance, Finite-Lived Intangible Assets			17,572	20,576			23,530	25,959			219	264
Net Balance, Indefinite-Lived Intangible Assets															35,452	35,537	4,400	4,400
Net Balance	$ 81,173	$ 86,736