Leases - Schedule of Rent Expense and Supplemental Cash Flow And Non Cash Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease expense	$ 7	$ 21
Variable lease expense	4	11
Operating cash flows for operating leases	7	20
Right-of-use assets obtained in exchange for lease obligations(1)	$ 65	$ 278