Business Combinations - Schedule of Preliminary Allocation of the Purchase Price (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Apr. 30, 2017	Dec. 31, 2016
Allocation of the purchase consideration:
Goodwill	$ 1,358,762		$ 1,228,503
SOASTA, Inc. [Member]
Allocation of the purchase consideration:
Cash		$ 1,935
Accounts receivable		4,108
Prepaids and other current assets		1,143
Identifiable intangible assets		49,900
Goodwill		121,669
Deferred tax assets		35,121
Total assets acquired		213,876
Accounts payable		(1,119)
Accrued liabilities		(3,915)
Deferred revenue		(9,562)
Total liabilities assumed		(14,596)
Net assets acquired		$ 199,280