Revenue (Condensed Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Condensed Consolidated Balance Sheet [Line Items]
Receivables, gross	$ 11,159	$ 11,456
Less: Allowance for doubtful accounts	475	352
Receivables, net	10,684	11,104
Noncurrent receivables, net (included in other noncurrent assets, net)	1,261	1,399
Contract acquisition and fulfillment costs (included in other noncurrent assets, net)	1,055	991
Noncurrent deferred revenue (included in other noncurrent liabilities)	663	650
NBCUniversal Media LLC [Member]
Condensed Consolidated Balance Sheet [Line Items]
Receivables, gross	7,139	7,392
Less: Allowance for doubtful accounts	99	99
Receivables, net	7,040	7,293
Noncurrent receivables, net (included in other noncurrent assets, net)	1,097	1,180
Noncurrent deferred revenue (included in other noncurrent liabilities)	$ 422	$ 481