Restructuring Costs - Schedule of Accrued Restructuring Costs Activity (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Restructuring Reserve [Roll Forward]
Beginning balance			$ 11
Restructuring costs, net	$ 6	$ 4	16	$ 14
Payments			(13)
Ending balance	14		14
Severance and termination costs
Restructuring Reserve [Roll Forward]
Beginning balance			7
Restructuring costs, net			13
Payments			(8)
Ending balance	12		12
Contract termination and other costs
Restructuring Reserve [Roll Forward]
Beginning balance			4
Restructuring costs, net			3
Payments			(5)
Ending balance	$ 2		$ 2