Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Cash Flows [Abstract]
Cash paid for interest, capitalized interest	$ 5	$ 5	$ 9
Restricted cash and equivalents	0	0	0
Financing leases	$ 3	4
Operating leases		$ 8
Capital leases			$ 8