Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Supplemental disclosures:
Cash paid for income taxes, net of refunds	$ 32	$ 8
Cash paid for interest	52	52
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from finance leases	3
Financing cash flows from finance leases	3
Non-cash investing activities:
Capital expenditures included in accounts payable	$ 8	$ 8