Goodwill, Customer Relationships and Other Intangible Assets - Rollforward of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
As of beginning of period	$ 15,986
Effect of foreign currency exchange rate change and other	(10)
As of end of period	15,976	$ 15,986
Accumulated impairment losses	7,700	7,700
Disposal Group, Held-for-sale, Not Discontinued Operations
Goodwill [Roll Forward]
Reclassified as held for sale	2,900	2,900
Business
Goodwill [Roll Forward]
As of beginning of period	11,235
Effect of foreign currency exchange rate change and other	(10)
As of end of period	11,225	11,235
Mass Markets
Goodwill [Roll Forward]
As of beginning of period	4,751
Effect of foreign currency exchange rate change and other	0
As of end of period	$ 4,751	$ 4,751