Reconciliation between Interest Expense and Cash Interest Paid (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Interest expense		$ 194	$ 222	$ 176
Amortization of debt premiums/discounts, net		(2)	(1)	(1)
Amortization of deferred financing costs		(6)	(5)	(6)
Non-cash losses on debt extinguishment		(1)	(6)
Change in accrued interest		(2)	9	2
Interest paid	[1]	$ 183	$ 219	$ 171

[1] Does not include capitalized interest of $5 million, $4 million and $3 million for 2020, 2019 and 2018, respectively.