Goodwill and Acquired Intangible Assets - Schedule of Acquired Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 279,611	$ 192,571
Accumulated Amortization	(121,990)	(115,142)
Net Carrying Amount	157,621	77,429
Completed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	92,431	65,631
Accumulated Amortization	(38,631)	(35,476)
Net Carrying Amount	53,800	30,155
Customer-related intangible assets
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	173,600	115,100
Accumulated Amortization	(78,708)	(75,563)
Net Carrying Amount	94,892	39,537
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,890	7,950
Accumulated Amortization	(3,060)	(2,623)
Net Carrying Amount	5,830	5,327
Trademarks and trade names
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,200	3,400
Accumulated Amortization	(1,101)	(990)
Net Carrying Amount	3,099	2,410
Acquired license rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	490	490
Accumulated Amortization	(490)	(490)
Net Carrying Amount	$ 0	$ 0