Goodwill Rollforward (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Goodwill beginning balance	$ 27,098,000,000us-gaap_Goodwill	$ 26,985,000,000us-gaap_Goodwill
Acquisitions	227,000,000us-gaap_GoodwillAcquiredDuringPeriod	42,000,000us-gaap_GoodwillAcquiredDuringPeriod
Adjustments	(9,000,000)us-gaap_GoodwillOtherChanges	71,000,000us-gaap_GoodwillOtherChanges
Goodwill ending balance	27,316,000,000us-gaap_Goodwill	27,098,000,000us-gaap_Goodwill
NBCUniversal Media, LLC [Member]
Goodwill beginning balance	14,882,000,000	14,770,000,000
Acquisitions	35,000,000	42,000,000
Adjustments	(9,000,000)	70,000,000
Goodwill ending balance	14,908,000,000	14,882,000,000
Cable Communications [Member]
Goodwill beginning balance	12,206,000,000	12,206,000,000
Acquisitions	11,000,000	0
Adjustments	0	0
Goodwill ending balance	12,217,000,000	12,206,000,000
Cable Networks [Member]
Goodwill beginning balance	13,130,000,000	13,026,000,000
Acquisitions	20,000,000	39,000,000
Adjustments	(202,000,000)	65,000,000
Goodwill ending balance	12,948,000,000	13,130,000,000
Cable Networks [Member] \| NBCUniversal Media, LLC [Member]
Goodwill beginning balance	13,130,000,000	13,026,000,000
Acquisitions	20,000,000	39,000,000
Adjustments	(202,000,000)	65,000,000
Goodwill ending balance	12,948,000,000	13,130,000,000
Broadcast Television [Member]
Goodwill beginning balance	769,000,000	761,000,000
Acquisitions	0	3,000,000
Adjustments	(2,000,000)	5,000,000
Goodwill ending balance	767,000,000	769,000,000
Broadcast Television [Member] \| NBCUniversal Media, LLC [Member]
Goodwill beginning balance	769,000,000	761,000,000
Acquisitions	0	3,000,000
Adjustments	(2,000,000)	5,000,000
Goodwill ending balance	767,000,000	769,000,000
Filmed Entertainment [Member]
Goodwill beginning balance	1,000,000	1,000,000
Acquisitions	15,000,000	0
Adjustments	195,000,000	0
Goodwill ending balance	211,000,000	1,000,000
Filmed Entertainment [Member] \| NBCUniversal Media, LLC [Member]
Goodwill beginning balance	1,000,000	1,000,000
Acquisitions	15,000,000	0
Adjustments	195,000,000	0
Goodwill ending balance	211,000,000	1,000,000
Theme Parks [Member]
Goodwill beginning balance	982,000,000	982,000,000
Acquisitions	0	0
Adjustments	0	0
Goodwill ending balance	982,000,000	982,000,000
Theme Parks [Member] \| NBCUniversal Media, LLC [Member]
Goodwill beginning balance	982,000,000	982,000,000
Acquisitions	0	0
Adjustments	0	0
Goodwill ending balance	982,000,000	982,000,000
Corporate and Other [Member]
Goodwill beginning balance	10,000,000	9,000,000
Acquisitions	181,000,000	0
Adjustments	0	1,000,000
Goodwill ending balance	$ 191,000,000	$ 10,000,000

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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