Restructuring Charges (Restructuring Liability) (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
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
Severance and Other Restructuring Liabilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	0	152	142	120
Restructuring Reserve [Roll Forward]
Accrued balance at beginning of period		59	66	61
Cash Payments	0	(120)	(137)	(109)
Other	0	$ 25	(18)	13
Accrued balance at end of period	$ 66		$ 53	$ 59