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Supplemental Condensed Consolidating Financial Information - Condensed Consolidating Statements of Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Statement of Income Captions [Line Items]
Net (loss) income	$ (262)	$ (97)	$ (230)	$ 77	$ (47)	$ 42	$ 33	$ 24	$ (512)	$ 52	$ 143
Other comprehensive income (loss), net of tax									(3)	2	(3)
Comprehensive (loss) income									(515)	54	140
Parent Guarantor
Condensed Statement of Income Captions [Line Items]
Net (loss) income									(512)	52	143
Other comprehensive income (loss), net of tax									(3)	2	(3)
Comprehensive (loss) income									(515)	54	140
Reportable Legal Entities \| Parent Guarantor
Condensed Statement of Income Captions [Line Items]
Net (loss) income									(512)	52	143
Other comprehensive income (loss), net of tax									(3)	2	(3)
Comprehensive (loss) income									(515)	54	140
Reportable Legal Entities \| Other Guarantors
Condensed Statement of Income Captions [Line Items]
Net (loss) income									(166)	9	15
Other comprehensive income (loss), net of tax									0	0	0
Comprehensive (loss) income									(166)	9	15
Reportable Legal Entities \| Non-Guarantors
Condensed Statement of Income Captions [Line Items]
Net (loss) income									(388)	110	175
Other comprehensive income (loss), net of tax									(2)	1	(3)
Comprehensive (loss) income									(390)	111	172
Eliminations
Condensed Statement of Income Captions [Line Items]
Net (loss) income									554	(119)	(190)
Other comprehensive income (loss), net of tax									2	(1)	3
Comprehensive (loss) income									$ 556	$ (120)	$ (187)