Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Rollforward Goodwill (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Goodwill Activity
As of beginning of period					$ 12,657
Impairment	$ 0	$ (8,800)		$ 0	(8,793)	$ 0
As of end of period	3,864		$ 12,657		3,864
Accumulated impairment losses	19,800		11,000		19,800
Business
Goodwill Activity
As of beginning of period					7,906
Impairment					(6,580)
As of end of period	1,326		7,906		1,326
Mass Markets
Goodwill Activity
As of beginning of period					4,751
Impairment					(2,213)
As of end of period	$ 2,538		$ 4,751		$ 2,538