Business Combinations - Schedule of Purchase Consideration (Details) - USD ($) $ in Thousands	May. 09, 2014	Dec. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill			$ 750,288	$ 750,288	$ 706,327
nPulse Technologies
Business Acquisition [Line Items]
Net tangible assets (liabilities)	$ (1,833)
Intangible assets	24,700
Deferred tax asset	442
Deferred tax liability	(8,368)
Goodwill	41,671
Total purchase price allocation	56,612
Cash	$ 55,200
Mandiant, Inc.
Business Acquisition [Line Items]
Net tangible assets (liabilities)				10,797
Intangible assets		$ 276,200		276,200
Deferred tax liability				(91,111)
Goodwill				704,904
Total purchase price allocation				$ 900,790
Cash		106,538
Fair value of common stock		704,414
Fair value of equity awards assumed		$ 89,838