Segment Information - Segment Results and Operating Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Operating revenues by products and services
Segment revenue	$ 3,221	$ 3,641	$ 9,779	$ 11,040
Cost of services and products	1,692	1,850	4,997	5,407
Business
Operating revenues by products and services
Segment revenue	2,536	2,905	7,704	8,781
Cost of services and products	766	825	2,266	2,428
Selling, general and administrative	453	610	1,407	1,723
Total segment expense	1,219	1,435	3,673	4,151
Total segment adjusted EBITDA	1,317	1,470	4,031	4,630
Mass Markets
Operating revenues by products and services
Segment revenue	685	736	2,075	2,259
Cost of services and products	16	19	53	61
Selling, general and administrative	323	364	937	1,038
Total segment expense	339	383	990	1,099
Total segment adjusted EBITDA	$ 346	$ 353	$ 1,085	$ 1,160