Segment Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financial Data by Business Segment
Revenue	$ 28,398	$ 26,827	$ 26,858	$ 26,859	$ 27,846	$ 22,135	$ 21,735	$ 22,791	$ 108,942	$ 94,507	$ 85,029
Adjusted EBITDA									34,258	30,165	27,956
Depreciation and Amortization									12,953	11,017	10,130
Capital Expenditures									9,953	9,774	9,550
Cash Paid for Intangible Assets									2,475	1,935	1,605
NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									34,021	35,895	32,950
Adjusted EBITDA									8,755	8,633	8,181
Depreciation and Amortization									2,129	2,108	2,041
Capital Expenditures									2,072	1,730	1,502
Cash Paid for Intangible Assets									285	448	295
Cable Networks [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									11,513	11,773	10,497
Broadcast Television [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									10,261	11,439	9,563
Filmed Entertainment [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									6,493	7,152	7,595
Theme Parks [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									5,933	5,683	5,443
NBCUniversal Segments [Member]
Financial Data by Business Segment
Revenue									33,967	35,761	32,836
Adjusted EBITDA									8,772	8,598	8,218
Depreciation and Amortization									2,129	2,108	2,041
Capital Expenditures									2,072	1,730	1,502
Cash Paid for Intangible Assets									285	448	295
Operating Segments [Member] | Cable Communications [Member]
Financial Data by Business Segment
Revenue									58,082	56,033	53,399
Adjusted EBITDA									23,266	21,681	20,555
Depreciation and Amortization									7,994	8,262	8,019
Capital Expenditures									6,909	7,723	7,978
Cash Paid for Intangible Assets									1,426	1,346	1,294
Operating Segments [Member] | Cable Networks [Member]
Financial Data by Business Segment
Revenue									11,513	11,773	10,497
Adjusted EBITDA									4,444	4,428	4,053
Depreciation and Amortization									735	738	755
Capital Expenditures									41	42	33
Cash Paid for Intangible Assets									17	23	19
Operating Segments [Member] | Cable Networks [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									11,513	11,773	10,497
Adjusted EBITDA									4,444	4,428	4,053
Depreciation and Amortization									735	738	755
Capital Expenditures									41	42	33
Cash Paid for Intangible Assets									17	23	19
Operating Segments [Member] | Broadcast Television [Member]
Financial Data by Business Segment
Revenue									10,261	11,439	9,563
Adjusted EBITDA									1,730	1,657	1,251
Depreciation and Amortization									157	146	133
Capital Expenditures									161	204	180
Cash Paid for Intangible Assets									15	81	22
Operating Segments [Member] | Broadcast Television [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									10,261	11,439	9,563
Adjusted EBITDA									1,730	1,657	1,251
Depreciation and Amortization									157	146	133
Capital Expenditures									161	204	180
Cash Paid for Intangible Assets									15	81	22
Operating Segments [Member] | Filmed Entertainment [Member]
Financial Data by Business Segment
Revenue									6,493	7,152	7,595
Adjusted EBITDA									833	734	1,276
Depreciation and Amortization									79	145	109
Capital Expenditures									21	35	58
Cash Paid for Intangible Assets									22	25	23
Operating Segments [Member] | Filmed Entertainment [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									6,493	7,152	7,595
Adjusted EBITDA									833	734	1,276
Depreciation and Amortization									79	145	109
Capital Expenditures									21	35	58
Cash Paid for Intangible Assets									22	25	23
Operating Segments [Member] | Theme Parks [Member]
Financial Data by Business Segment
Revenue									5,933	5,683	5,443
Adjusted EBITDA									2,455	2,455	2,384
Depreciation and Amortization									696	660	648
Capital Expenditures									1,605	1,143	960
Cash Paid for Intangible Assets									60	173	78
Operating Segments [Member] | Theme Parks [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									5,933	5,683	5,443
Adjusted EBITDA									2,455	2,455	2,384
Depreciation and Amortization									696	660	648
Capital Expenditures									1,605	1,143	960
Cash Paid for Intangible Assets									60	173	78
Operating Segments [Member] | NBCUniversal Segments [Member]
Financial Data by Business Segment
Revenue									33,967	35,761	32,836
Operating Segments [Member] | Sky Limited [Member]
Financial Data by Business Segment
Revenue									19,219	4,587	0
Adjusted EBITDA									3,099	692
Depreciation and Amortization									2,699	539
Capital Expenditures									768	222
Cash Paid for Intangible Assets									707	137
Corporate, Non-Segment [Member]
Financial Data by Business Segment
Revenue									333	513	864
Adjusted EBITDA									(880)	(779)	(859)
Depreciation and Amortization									131	108	70
Capital Expenditures									204	99	70
Cash Paid for Intangible Assets									57	4	16
Corporate, Non-Segment [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									142	212	179
Adjusted EBITDA									(706)	(645)	(779)
Depreciation and Amortization									462	419	396
Capital Expenditures									244	306	271
Cash Paid for Intangible Assets									171	146	153
Corporate, Non-Segment [Member] | NBCUniversal Segments [Member]
Financial Data by Business Segment
Revenue									83	63	45
Adjusted EBITDA									(689)	(680)	(741)
Depreciation and Amortization									462	419	396
Capital Expenditures									244	306	271
Cash Paid for Intangible Assets									171	146	153
Eliminations [Member]
Financial Data by Business Segment
Revenue									(2,659)	(2,387)	(2,070)
Adjusted EBITDA									1	(27)	42
Depreciation and Amortization									0	0	0
Capital Expenditures									0	0	0
Cash Paid for Intangible Assets									0	0	0
Eliminations [Member] | NBCUniversal Media LLC [Member]
Financial Data by Business Segment
Revenue									(321)	(364)	(327)
Adjusted EBITDA									(1)	4	(4)
Depreciation and Amortization									0	0	0
Capital Expenditures									0	0	0
Cash Paid for Intangible Assets									0	0	0
Eliminations [Member] | NBCUniversal Segments [Member]
Financial Data by Business Segment
Revenue									(316)	(349)	(307)
Adjusted EBITDA									(1)	4	(5)
Depreciation and Amortization									0	0	0
Capital Expenditures									0	0	0
Cash Paid for Intangible Assets									$ 0	$ 0	$ 0