Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Interest paid, net of amounts capitalized	$ 118	$ 133	$ 130
Taxes paid, net of refunds	157	100	123
Noncash Investing and Financing Activities
Accrued treasury stock repurchases	4	13	0
Accrued capital expenditures	20	(4)	14
Asset retirement obligations	(6)	(7)	(2)
Fair value adjustment to securities available for sale, net of tax	$ 0	$ 0	$ (1)