Segment Information - Segment Results and Operating Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating revenues by products and services
Segment revenue	$ 3,268	$ 3,661	$ 6,558	$ 7,399
Cost of services and products	1,653	1,740	3,305	3,557
Business
Operating revenues by products and services
Segment revenue	2,577	2,908	5,168	5,876
Cost of services and products	761	773	1,500	1,603
Selling, general and administrative	457	570	954	1,113
Total segment expense	1,218	1,343	2,454	2,716
Total segment adjusted EBITDA	1,359	1,565	2,714	3,160
Mass Markets
Operating revenues by products and services
Segment revenue	691	753	1,390	1,523
Cost of services and products	20	21	37	42
Selling, general and administrative	308	339	614	674
Total segment expense	328	360	651	716
Total segment adjusted EBITDA	$ 363	$ 393	$ 739	$ 807