Segment Information (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ 1,309		$ 1,448	$ 2,655	$ 2,871
Operating Income (Loss)	(118)		(73)	(419)	(112)
Depreciation and Amortization	116		144	239	291
Corporate General and Administrative	32		34	64	70
Goodwill, Impairment Loss	(102)	$ (229)	0	(331)	0	$ 0
Prepetition charges	(76)		0	(86)	0
Restructuring Charges	(20)		(38)	(40)	(63)
Gain (Loss) on Disposition of Business	114		0	112	0
Gain (Loss) on Disposition of Assets				112	0
Western Hemisphere
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss				(229)
Eastern Hemisphere
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss				102
Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,309		1,448	2,655	2,871
Operating Income (Loss)	39		69	68	109
Depreciation and Amortization	115		140	235	286
Operating Segments | Western Hemisphere
Segment Reporting Information [Line Items]
Revenues	719		769	1,445	1,525
Operating Income (Loss)	11		50	20	74
Depreciation and Amortization	45		56	93	116
Operating Segments | Eastern Hemisphere
Segment Reporting Information [Line Items]
Revenues	590		679	1,210	1,346
Operating Income (Loss)	28		19	48	35
Depreciation and Amortization	70		84	142	170
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Depreciation and Amortization	1		4	4	5
Corporate General and Administrative	32		34	64	70
Segment Reconciling Items
Segment Reporting Information [Line Items]
Goodwill, Impairment Loss				(331)
Restructuring Charges	(20)		(38)	(40)	(63)
Impairment of Long-Lived Assets and Other Related Charges	(41)		$ (70)	(78)	$ (88)
Gain (Loss) on Disposition of Business	$ 114
Gain (Loss) on Disposition of Assets				$ 112