Summary of Significant Accounting Policies, Supplementary Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplementary Cash Flow Information [Abstract]
Cash payments made for interest on long term debt, net of capitalized interest	$ 463	$ 560	$ 558
Cash payments for federal, foreign, state and local income taxes amount	20	190	101
Accrued capital expenditures	$ 63	$ 17	$ 15