Summary of Significant Accounting Policies (Details) - USD ($)	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
Revenue by Product Line
Revenues	$ 11,761,000,000	$ 11,450,000,000	$ 11,347,000,000	$ 11,206,000,000	$ 11,231,000,000	$ 10,892,000,000	$ 10,854,000,000	$ 10,657,000,000	$ 45,764,000,000	$ 43,634,000,000	$ 41,581,000,000
Impairment of long-lived assets held-for-use									0	0	0
Impairment of long-lived assets held for sale									41,000,000	75,000,000
Governmental imposed fees passed through to the customer									1,100,000,000	1,000,000,000.0	961,000,000
Customer prepayments - account payable and accrued liabilities	366,000,000				410,000,000				366,000,000	410,000,000
Upfront installation fees - account payable and accrued liabilities	94,000,000				84,000,000				94,000,000	84,000,000
Long-term deferred revenue liabilities - other long-term liabilities	34,000,000				34,000,000				34,000,000	34,000,000
Deferred enterprise commission costs - noncurrent asset	143,000,000				142,000,000				143,000,000	142,000,000
Deferred upfront MDU fees - noncurrent asset	$ 284,000,000				$ 273,000,000				284,000,000	273,000,000
Amortization expense of deferred upfront MDU fees									67,000,000	62,000,000
Programming costs									$ 11,290,000,000	$ 11,124,000,000	$ 10,596,000,000
Number of reportable segments									1
Weighted average assumptions used to estimate the fair value of stock options at the date of grant:
Risk-free interest rate (percentage)									2.50%	2.40%	1.80%
Expected volatility rate (percentage)									27.00%	25.00%	25.00%
Expected life (in years)									4 years 10 months 24 days	5 years 1 month 6 days	4 years 7 months 6 days
Maximum | Cable distribution systems
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									20 years
Maximum | Customer premise equipment and installations
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									8 years
Maximum | Vehicles and equipment
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									21 years
Maximum | Buildings and improvements
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									40 years
Maximum | Furniture, fixtures and equipment
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									10 years
Minimum | Cable distribution systems
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									8 years
Minimum | Customer premise equipment and installations
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									3 years
Minimum | Vehicles and equipment
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									6 years
Minimum | Buildings and improvements
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									10 years
Minimum | Furniture, fixtures and equipment
Property, Plant and Equipment
Property, plant and equipment, useful life (in years)									2 years
Video
Revenue by Product Line
Revenues									$ 17,607,000,000	$ 17,348,000,000	$ 16,621,000,000
Internet
Revenue by Product Line
Revenues									16,667,000,000	15,181,000,000	14,101,000,000
Voice
Revenue by Product Line
Revenues									1,920,000,000	2,114,000,000	2,542,000,000
Residential revenue
Revenue by Product Line
Revenues									36,194,000,000	34,643,000,000	33,264,000,000
Small and medium business
Revenue by Product Line
Revenues									3,868,000,000	3,665,000,000	3,547,000,000
Enterprise
Revenue by Product Line
Revenues									2,556,000,000	2,528,000,000	2,373,000,000
Commercial revenue
Revenue by Product Line
Revenues									6,424,000,000	6,193,000,000	5,920,000,000
Advertising sales
Revenue by Product Line
Revenues									1,568,000,000	1,785,000,000	1,510,000,000
Mobile
Revenue by Product Line
Revenues									726,000,000	106,000,000	0
Other
Revenue by Product Line
Revenues									$ 852,000,000	$ 907,000,000	$ 887,000,000