Restructuring Charges (Restructuring Charges) (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 13, 2019	Dec. 31, 2020	Dec. 31, 2018	Dec. 12, 2019	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 0	$ 189	$ 206	$ 126
Western Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0	84	101	27
Eastern Hemisphere [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0	50	52	45
Corporate and Other
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0	55	53	54
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	0	53	132	61
Severance and Other Restructuring Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	66		53	59	$ 66	$ 61
Impaired Assets to be Disposed of by Method Other than Sale, Asset Name [Domain]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	0	13	40	2
Facility Closing
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	0	99	10	61
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	0	24	15	0
Asset Retirement Obligation Costs
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	$ 0	$ 0	$ 9	$ 2