Segment Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 1,444	$ 1,460	$ 4,315	$ 4,209
Operating Income (Loss)	(13)	(70)	(125)	(429)
Depreciation and Amortization	128	199	419	611
Corporate General and Administrative	(31)	(42)	(106)	(117)
Restructuring Charges	(27)	(34)	(90)	(140)
Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,444	1,460	4,315	4,209
Operating Income (Loss)	116	(7)	225	(169)
Depreciation and Amortization	127	197	413	606
Operating Segments \| Western Hemisphere
Segment Reporting Information [Line Items]
Revenues	762	767	2,287	2,178
Operating Income (Loss)	78	3	152	(78)
Depreciation and Amortization	46	89	162	272
Operating Segments \| Eastern Hemisphere
Segment Reporting Information [Line Items]
Revenues	682	693	2,028	2,031
Operating Income (Loss)	38	(10)	73	(91)
Depreciation and Amortization	81	108	251	334
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Depreciation and Amortization	1	2	6	5
Corporate General and Administrative	(31)	(28)	(101)	(94)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Restructuring Charges	(27)	(34)	(90)	140
Impairment of Long-Lived Assets and Other Related Charges	$ (71)	$ (1)	$ (159)	$ (26)

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