Shareholders' Deficit (Details 2) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of changes in accumulated comprehensive income [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				$ 2
Beginning Accumulated Other Comprehensive Income (Loss), Net of Tax				(271)
Gains (losses) arising during the year classified into accumulated OCI, net of tax				(8)
(Gains) losses reclassified from accumulated OCI, net of tax				(5)
Other comprehensive income (loss), net of tax		$ (67)	$ (13)	(13)	$ 62
Ending Accumulated Other Comprehensive Income (Loss), Net of Tax		(282)		(282)
Translation Adjustments and Gains (Losses) From Intra-Entity Transactions of a Long-Term Nature
Schedule of changes in accumulated comprehensive income [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	[1]			21
Beginning Accumulated Other Comprehensive Income (Loss), Net of Tax				(174)
Gains (losses) arising during the year classified into accumulated OCI, net of tax				(30)
(Gains) losses reclassified from accumulated OCI, net of tax				0
Other comprehensive income (loss), net of tax				(30)
Ending Accumulated Other Comprehensive Income (Loss), Net of Tax		(183)		(183)
Pension and Post-Retirement Benefits
Schedule of changes in accumulated comprehensive income [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	[2]			(17)
Beginning Accumulated Other Comprehensive Income (Loss), Net of Tax				(106)
Gains (losses) arising during the year classified into accumulated OCI, net of tax				0
(Gains) losses reclassified from accumulated OCI, net of tax				8
Other comprehensive income (loss), net of tax				8
Ending Accumulated Other Comprehensive Income (Loss), Net of Tax		(115)		(115)
Derivative Instruments
Schedule of changes in accumulated comprehensive income [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	[2]			(2)
Beginning Accumulated Other Comprehensive Income (Loss), Net of Tax				9
Gains (losses) arising during the year classified into accumulated OCI, net of tax				22
(Gains) losses reclassified from accumulated OCI, net of tax				(13)
Other comprehensive income (loss), net of tax				9
Ending Accumulated Other Comprehensive Income (Loss), Net of Tax		$ 16		16
Balances with Adoption of Topic 606 [Domain]
Schedule of changes in accumulated comprehensive income [Line Items]
Other comprehensive income (loss), net of tax				$ (13)

[1] Represents the impact of foreign currency translation from the adoption of Topic 606. See Notes 2 and 5.

[2] During the quarter ended March 31, 2018, we adopted a standard that allows for the reclassification from AOCI to Accumulated deficit for stranded tax effects resulting from the Tax Act. See Note 1.