Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 26,609	$ 26,859
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%	2.60%
NBCUniversal Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 7,734	$ 8,313
Operating Segments [Member] | Cable Communications [Member]
Disaggregation of Revenue [Line Items]
Revenue	14,918	14,280
Operating Segments [Member] | Cable Communications [Member] | Residential, High-Speed Internet [Member]
Disaggregation of Revenue [Line Items]
Revenue	5,001	4,577
Operating Segments [Member] | Cable Communications [Member] | Residential, Video [Member]
Disaggregation of Revenue [Line Items]
Revenue	5,632	5,628
Operating Segments [Member] | Cable Communications [Member] | Residential, Voice [Member]
Disaggregation of Revenue [Line Items]
Revenue	899	990
Operating Segments [Member] | Cable Communications [Member] | Residential, Wireless [Member]
Disaggregation of Revenue [Line Items]
Revenue	343	225
Operating Segments [Member] | Cable Communications [Member] | Business Services [Member]
Disaggregation of Revenue [Line Items]
Revenue	2,043	1,891
Operating Segments [Member] | Cable Communications [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	557	556
Operating Segments [Member] | Cable Communications [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	443	413
Operating Segments [Member] | Cable Networks [Member]
Disaggregation of Revenue [Line Items]
Revenue	2,859	2,868
Operating Segments [Member] | Cable Networks [Member] | Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,708	1,735
Operating Segments [Member] | Cable Networks [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	834	852
Operating Segments [Member] | Cable Networks [Member] | Content Licensing And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	317	281
Operating Segments [Member] | Broadcast Television [Member]
Disaggregation of Revenue [Line Items]
Revenue	2,684	2,467
Operating Segments [Member] | Broadcast Television [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,318	1,317
Operating Segments [Member] | Broadcast Television [Member] | Content Licensing [Member]
Disaggregation of Revenue [Line Items]
Revenue	735	560
Operating Segments [Member] | Broadcast Television [Member] | Distribution And Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	631	590
Operating Segments [Member] | Filmed Entertainment [Member]
Disaggregation of Revenue [Line Items]
Revenue	1,370	1,768
Operating Segments [Member] | Filmed Entertainment [Member] | Theatrical [Member]
Disaggregation of Revenue [Line Items]
Revenue	317	445
Operating Segments [Member] | Filmed Entertainment [Member] | Content Licensing [Member]
Disaggregation of Revenue [Line Items]
Revenue	691	817
Operating Segments [Member] | Filmed Entertainment [Member] | Home Entertainment [Member]
Disaggregation of Revenue [Line Items]
Revenue	171	267
Operating Segments [Member] | Filmed Entertainment [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue	191	239
Operating Segments [Member] | Theme Parks [Member]
Disaggregation of Revenue [Line Items]
Revenue	869	1,276
Operating Segments [Member] | NBCUniversal Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	7,734	8,313
Operating Segments [Member] | Sky Limited [Member]
Disaggregation of Revenue [Line Items]
Revenue	4,517	4,797
Operating Segments [Member] | Sky Limited [Member] | Direct To Consumer [Member]
Disaggregation of Revenue [Line Items]
Revenue	3,679	3,834
Operating Segments [Member] | Sky Limited [Member] | Content [Member]
Disaggregation of Revenue [Line Items]
Revenue	325	370
Operating Segments [Member] | Sky Limited [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Revenue	513	593
Corporate, Non-Segment [Member]
Disaggregation of Revenue [Line Items]
Revenue	120	108
Corporate, Non-Segment [Member] | NBCUniversal Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	23	17
Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	(680)	(639)
Eliminations [Member] | NBCUniversal Segments [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ (71)	$ (83)