Segment Information - Segment Results and Operating Revenue (Details ) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating revenues by products and services
Revenues	$ 19,687	$ 20,712	$ 21,458
Cost of services and products	8,488	8,934	9,134
Selling, general and administrative	2,895	3,464	3,715
Less: stock-based compensation	(120)	(175)	(162)
Total expense	11,263	12,223	12,687
Total segment adjusted EBITDA	8,424	8,489	8,771
Operating Segments
Operating revenues by products and services
Revenues	19,687	20,712	21,458
Cost of services and products	3,636	3,852	3,812
Selling, general and administrative	1,719	1,843	1,994
Less: stock-based compensation	0	0	0
Total expense	5,355	5,695	5,806
Total segment adjusted EBITDA	14,332	15,017	15,652
Operating Segments | Business
Operating revenues by products and services
Revenues	14,119	14,817	15,239
Cost of services and products	3,484	3,649	3,598
Selling, general and administrative	1,189	1,269	1,364
Less: stock-based compensation	0	0	0
Total expense	4,673	4,918	4,962
Total segment adjusted EBITDA	9,446	9,899	10,277
Operating Segments | Mass Markets
Operating revenues by products and services
Revenues	5,568	5,895	6,219
Cost of services and products	152	203	214
Selling, general and administrative	530	574	630
Less: stock-based compensation	0	0	0
Total expense	682	777	844
Total segment adjusted EBITDA	4,886	5,118	5,375
Operations and Other
Operating revenues by products and services
Revenues	0	0	0
Cost of services and products	4,852	5,082	5,322
Selling, general and administrative	1,176	1,621	1,721
Less: stock-based compensation	(120)	(175)	(162)
Total expense	5,908	6,528	6,881
Total segment adjusted EBITDA	$ (5,908)	$ (6,528)	$ (6,881)