Leases - Schedule Of Supplemental Cash Flow Related To Leases (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 177	$ 201
Operating cash flows from finance leases	0	1
Financing cash flows from finance leases	4	4
Right of use assets obtained in exchange for lease liabilities:
Operating leases	75	130
Finance leases	$ 0	$ 7