Segment and Related Information - Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Goodwill, Beginning Balance	$ 8,994	$ 6,532
Acquired goodwill	76	2,470
Divested goodwill	(47)	(15)
Impairments			$ (27)
Foreign currency translation and other	5	7
Goodwill, Ending Balance	9,028	8,994	6,532
Goodwill post-closing adjustment increase (decrease)	(26)
East Tier [Member]
Segment Reporting Information [Line Items]
Goodwill, Beginning Balance	5,101	3,616
Acquired goodwill	27	1,479
Divested goodwill	(11)	(3)
Foreign currency translation and other	3	9
Goodwill, Ending Balance	5,120	5,101	3,616
West Tier [Member]
Segment Reporting Information [Line Items]
Goodwill, Beginning Balance	3,823	2,846
Acquired goodwill	15	991
Divested goodwill	(7)	(12)
Foreign currency translation and other	2	(2)
Goodwill, Ending Balance	3,833	3,823	2,846
Other [Member]
Segment Reporting Information [Line Items]
Goodwill, Beginning Balance	70	70
Acquired goodwill	34
Divested goodwill	(29)
Goodwill, Ending Balance	$ 75	$ 70	$ 70