Goodwill and Acquired Intangible Assets - Schedule of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($)
Schedule of Goodwill [Roll Forward]
Balance as of January 1, 2016	$ 1,150,244
Foreign currency translation	(107)
Balance as of September 30, 2016	1,151,216
Concord Systems, Inc. [Member]
Schedule of Goodwill [Roll Forward]
Acquisition of Concord Systems, Inc.	1,079
Balance as of September 30, 2016	$ 1,100