Segment Information Segment Information (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 13, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 261	$ 4,954	$ 3,685		$ 5,744
Operating Income (Loss)	1	(1,182)	(1,486)		(2,084)
Asset Impairment Charges	0	(1,104)	(1,236)		(2,155)
Restructuring Charges	0	(189)	(206)		(126)
Prepetition Charges	0	(86)	0	$ (86)	0
Gain on Sale of Operational Assets	0	15	12		0
Gain (Loss) on Disposition of Business	0	112	0		0
Interest Expense, Net	(12)	(362)	(266)		(614)
Reorganization Items	(4)	5,389	(9)		0
Other Expense, Net	0	(26)	(53)		(59)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(15)	3,819	(1,814)		(2,757)
Depreciation and Amortization	34	447	503		556
Capital Expenditures for Property, Plant and Equipment	(20)	(250)	(154)		(186)
Total Assets	7,293		5,434	7,293
Eastern Hemisphere [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	0	(50)	(52)		(45)
Depreciation and Amortization	20	269	369		333
Capital Expenditures for Property, Plant and Equipment	(7)	(115)	(59)		(87)
Total Assets	4,392		3,089	4,392
Western Hemisphere [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	0	(84)	(101)		(27)
Depreciation and Amortization	14	171	134		216
Capital Expenditures for Property, Plant and Equipment	(9)	(113)	(79)		(81)
Total Assets	2,514		1,636	2,514
Corporate and Other
Segment Reporting Information [Line Items]
General and Administrative Expense	5	118	111		130
Restructuring Charges	0	(55)	(53)		(54)
Depreciation and Amortization	0	7	0		7
Capital Expenditures for Property, Plant and Equipment	(4)	(22)	(16)		(18)
Total Assets	387		709	$ 387
Operating Segments [Member]
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	261	4,954	3,685		5,744
Operating Income (Loss)	6	188	55		327
Operating Segments [Member] | Eastern Hemisphere [Member]
Segment Reporting Information [Line Items]
Revenues	140	2,334	2,099		2,681
Operating Income (Loss)	10	134	37		119
Operating Segments [Member] | Western Hemisphere [Member]
Segment Reporting Information [Line Items]
Revenues	121	2,620	1,586		3,063
Operating Income (Loss)	$ (4)	$ 54	$ 18		$ 208