Investments (Equity Method Investments) (Details) - USD ($)		1 Months Ended				3 Months Ended	12 Months Ended
	Jan. 01, 2016	Aug. 31, 2019	May 31, 2019	Apr. 30, 2018	Jul. 31, 2017	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 30, 2019	Feb. 28, 2018	Aug. 31, 2016	Jul. 31, 2016
Schedule of Equity Method Investments [Line Items]
Equity in net income (losses) of investees, net							$ (505,000,000)	$ (364,000,000)	$ 107,000,000
Equity method investments							5,347,000,000	4,035,000,000
Proceeds from collateralized obligation		$ 5,200,000,000					5,175,000,000	0	0
Collateralized obligation							5,166,000,000	0
Investment securing collateralized obligation							694,000,000	0
NBCUniversal Media LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity in net income (losses) of investees, net							(402,000,000)	(371,000,000)	(201,000,000)
Equity method investments							1,156,000,000	707,000,000
Proceeds from collateralized obligation		$ 5,200,000,000					5,175,000,000	0	0
Collateralized obligation							5,166,000,000	0
Investment securing collateralized obligation							694,000,000	0
Atairos [Member]
Schedule of Equity Method Investments [Line Items]
Pretax gain, sale of business to Atairos				$ 200,000,000	$ 105,000,000
Atairos [Member]
Schedule of Equity Method Investments [Line Items]
Term of agreement	12 years
Funding commitment											$ 5,000,000,000
Management fee funding commitment											45,000,000
Percent of losses	99.00%
Percentage of residual returns	86.00%
Equity in net income (losses) of investees, net							(64,000,000)	(31,000,000)	281,000,000
Cash capital contributions for equity method investments							571,000,000	282,000,000	994,000,000
Equity method investments							3,200,000,000	2,700,000,000
Atairos [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Funding commitment by management company investors											50,000,000
Atairos [Member] | Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Funding commitment by management company investors											$ 100,000,000
Atairos [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Schedule of Equity Method Investments [Line Items]
Unfunded capital commitment							2,200,000,000
Atairos [Member] | Former CFO [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Funding commitment by management company investors	$ 40,000,000
Hulu [Member]
Schedule of Equity Method Investments [Line Items]
Equity in net income (losses) of investees, net							(473,000,000)	(454,000,000)	(276,000,000)
Equity method investments								248,000,000
Ownership percentage			33.00%							30.00%		30.00%	33.00%
Cash capital contributions for equity method investments			$ 477,000,000				903,000,000	454,000,000	300,000,000
Maximum total capital call in annual period			$ 1,500,000,000
Ownership percentage floor			21.00%
Fair market value assessment floor for put and call option			$ 27,500,000,000
Ownership percentage representing fair market value floor for put and call option			100.00%
Minimum guaranteed proceeds floor for put and call option			$ 5,800,000,000
Deferred gain						$ 159,000,000
Hulu [Member] | NBCUniversal Media LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity in net income (losses) of investees, net							(473,000,000)	(454,000,000)	(276,000,000)
Equity method investments								248,000,000
Ownership percentage			33.00%							30.00%		30.00%	33.00%
Cash capital contributions for equity method investments			$ 477,000,000				903,000,000	$ 454,000,000	$ 300,000,000
Maximum total capital call in annual period			$ 1,500,000,000
Ownership percentage floor			21.00%
Fair market value assessment floor for put and call option			$ 27,500,000,000
Ownership percentage representing fair market value floor for put and call option			100.00%
Minimum guaranteed proceeds floor for put and call option			$ 5,800,000,000
Deferred gain						$ 159,000,000
Hulu [Member] | AT&T Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage			10.00%
Hulu [Member] | AT&T Inc. [Member] | NBCUniversal Media LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage			10.00%
Hulu [Member] | Time Warner, Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage												10.00%
Hulu [Member] | Time Warner, Inc. [Member] | NBCUniversal Media LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage												10.00%
Level 2 [Member]
Schedule of Equity Method Investments [Line Items]
Estimated fair value of collateralized obligation							5,200,000,000
Level 2 [Member] | NBCUniversal Media LLC [Member]
Schedule of Equity Method Investments [Line Items]
Estimated fair value of collateralized obligation							$ 5,200,000,000