Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 101,561	$ 95,743
Less: Accumulated depreciation	53,239	51,306
Property and equipment, net	48,322	44,437
NBCUniversal Media LLC [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	21,550	18,183
Less: Accumulated depreciation	5,799	4,994
Property and equipment, net	$ 15,751	13,189
Distribution System [Member]
Property, Plant and Equipment [Line Items]
Weighted-Average Original Useful Life	11 years
Property and equipment, at cost	$ 40,639	38,380
Customer Premise Equipment [Member]
Property, Plant and Equipment [Line Items]
Weighted-Average Original Useful Life	6 years
Property and equipment, at cost	$ 26,065	26,208
Other Equipment [Member]
Property, Plant and Equipment [Line Items]
Weighted-Average Original Useful Life	9 years
Property and equipment, at cost	$ 13,025	12,437
Buildings and Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Weighted-Average Original Useful Life	30 years
Property and equipment, at cost	$ 15,104	14,188
Buildings and Leasehold Improvements [Member] | NBCUniversal Media LLC [Member]
Property, Plant and Equipment [Line Items]
Weighted-Average Original Useful Life	31 years
Property and equipment, at cost	$ 9,438	8,877
Furniture, Fixtures and Equipment [Member] | NBCUniversal Media LLC [Member]
Property, Plant and Equipment [Line Items]
Weighted-Average Original Useful Life	12 years
Property and equipment, at cost	$ 6,049	5,501
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	5,245	2,991
Construction in Process [Member] | NBCUniversal Media LLC [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	4,884	2,676
Land [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	1,483	1,539
Land [Member] | NBCUniversal Media LLC [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, at cost	$ 1,179	$ 1,129