Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 26,859	$ 22,791
Cable Communications [Member]
Disaggregation of Revenue [Line Items]
Revenue	14,280	13,703
Cable Communications [Member] | Residential, High-Speed Internet [Member]
Disaggregation of Revenue [Line Items]
Revenue	4,577	4,157
Cable Communications [Member] | Residential, Video [Member]
Disaggregation of Revenue [Line Items]
Revenue	5,628	5,659
Cable Communications [Member] | Residential, Voice [Member]
Disaggregation of Revenue [Line Items]
Revenue	990	1,006
Cable Communications [Member] | Residential, Wireless [Member]
Disaggregation of Revenue [Line Items]
Revenue	225	185
Cable Communications [Member] | Business Services [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,891	1,726
Cable Communications [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	556	582
Cable Communications [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 413	$ 388
Cable Communications [Member] | Franchise And Other Regulatory Fees [Member]
Disaggregation of Revenue [Line Items]
Cable segment revenue types as percentage of total cable revenue	2.60%	2.70%
Cable Networks [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 2,868	$ 3,157
Cable Networks [Member] | Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,735	1,861
Cable Networks [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	852	977
Cable Networks [Member] | Content Licensing And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	281	319
Broadcast Television [Member]
Disaggregation of Revenue [Line Items]
Revenue	2,467	3,497
Broadcast Television [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,317	2,365
Broadcast Television [Member] | Content Licensing [Member]
Disaggregation of Revenue [Line Items]
Revenue	560	522
Broadcast Television [Member] | Distribution And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	590	610
Filmed Entertainment [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,768	1,647
Filmed Entertainment [Member] | Content Licensing [Member]
Disaggregation of Revenue [Line Items]
Revenue	817	733
Filmed Entertainment [Member] | Theatrical [Member]
Disaggregation of Revenue [Line Items]
Revenue	445	423
Filmed Entertainment [Member] | Home Entertainment [Member]
Disaggregation of Revenue [Line Items]
Revenue	267	248
Filmed Entertainment [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	239	243
Theme Parks [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,276	1,281
NBCUniversal Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	8,313	9,497
Sky Limited [Member]
Disaggregation of Revenue [Line Items]
Revenue	4,797	0
Sky Limited [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	593	0
Sky Limited [Member] | Direct To Consumer [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,834	0
Sky Limited [Member] | Content [Member]
Disaggregation of Revenue [Line Items]
Revenue	370	0
Corporate, Non-Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue	108	243
Corporate, Non-Segment [Member] | NBCUniversal Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	17	14
Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	(639)	(652)
Eliminations [Member] | NBCUniversal Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	(83)	(99)
NBCUniversal Media LLC [Member]
Disaggregation of Revenue [Line Items]
Revenue	8,345	9,530
NBCUniversal Media LLC [Member] | Cable Networks [Member]
Disaggregation of Revenue [Line Items]
Revenue	2,868	3,157
NBCUniversal Media LLC [Member] | Cable Networks [Member] | Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,735	1,861
NBCUniversal Media LLC [Member] | Cable Networks [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	852	977
NBCUniversal Media LLC [Member] | Cable Networks [Member] | Content Licensing And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	281	319
NBCUniversal Media LLC [Member] | Broadcast Television [Member]
Disaggregation of Revenue [Line Items]
Revenue	2,467	3,497
NBCUniversal Media LLC [Member] | Broadcast Television [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,317	2,365
NBCUniversal Media LLC [Member] | Broadcast Television [Member] | Content Licensing [Member]
Disaggregation of Revenue [Line Items]
Revenue	560	522
NBCUniversal Media LLC [Member] | Broadcast Television [Member] | Distribution And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	590	610
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,768	1,647
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Content Licensing [Member]
Disaggregation of Revenue [Line Items]
Revenue	817	733
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Theatrical [Member]
Disaggregation of Revenue [Line Items]
Revenue	445	423
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Home Entertainment [Member]
Disaggregation of Revenue [Line Items]
Revenue	267	248
NBCUniversal Media LLC [Member] | Filmed Entertainment [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	239	243
NBCUniversal Media LLC [Member] | Theme Parks [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,276	1,281
NBCUniversal Media LLC [Member] | Corporate, Non-Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue	51	51
NBCUniversal Media LLC [Member] | Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ (85)	$ (103)