Restructuring and Other Charges, Net - Activity and Reserve Balances for Restructuring Charges (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	$ 63	$ 137
Restructuring and other charges, net	12	52
Cash payments	(27)	(120)
Reversals and other	(6)	(6)
Restructuring reserve ending balance	42	63
Severance and Employee Termination Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	6	35
Restructuring and other charges, net		16
Cash payments	(4)	(41)
Reversals and other		(4)
Restructuring reserve ending balance	2	6
Other Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring reserve beginning balance	57	102
Restructuring and other charges, net	12	36
Cash payments	(23)	(79)
Reversals and other	(6)	(2)
Restructuring reserve ending balance	$ 40	$ 57