Acquisitions (Schedule of Total Consideration) (Details) - USD ($) $ in Millions	Feb. 09, 2017	Aug. 01, 2016
Blue Coat, Inc.
Business Acquisition [Line Items]
Cash and equity consideration for outstanding of common shares and restricted stock awards and vested equity awards		$ 2,006
Cash consideration for outstanding Blue Coat debt		1,910
Issuance of Symantec 2.0% convertible debt to Bain Capital Funds (selling shareholder)		750
Fair value of vested assumed options and equity awards		102
Cash consideration for acquiree acquisition-related expenses		51
Total consideration		4,819
Cash acquired		(146)
Net consideration transferred		$ 4,673
LifeLock
Business Acquisition [Line Items]
Cash and equity consideration for outstanding of common shares and restricted stock awards and vested equity awards	$ 2,298
Fair value of vested assumed options and equity awards	10
Liability assumed for dissenting shareholders	68
Liability assumed for lost shareholders	1
Total consideration	2,377
Cash acquired	(94)
Net consideration transferred	$ 2,283