Significant Transactions (DreamWorks Animation) (Details) - DreamWorks Animation [Member] $ / shares in Units, $ in Millions	Aug. 22, 2016 USD ($) $ / shares
Business Acquisition [Line Items]
Cash consideration transferred	$ 3,773
Business acquisition, price paid per share (in dollars per share) \| $ / shares	$ 41
NBCUniversal Media LLC [Member]
Business Acquisition [Line Items]
Cash consideration transferred	$ 3,773
Consideration Transferred By Comcast [Member] \| NBCUniversal Media LLC [Member]
Business Acquisition [Line Items]
Cash consideration transferred	$ 3,800
Business acquisition, price paid per share (in dollars per share) \| $ / shares	$ 41

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

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