Leases - Operating Leases Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 27	$ 27	$ 80	$ 80
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 7	$ 12	$ 26	$ 28
Weighted-average remaining lease term (years)	6 years 3 months 18 days	6 years 10 months 24 days	6 years 3 months 18 days	6 years 10 months 24 days
Weighted-average discount rate applied to operating leases (percent)	3.60%	3.60%	3.60%	3.60%