Fair Value Measurements Changes in Fair Value Level 3 (Details) - Level 3 - Recurring measurement - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of asset measured on a recurring basis	$ 279	$ 212	$ 283
Realized and unrealized gains (losses), net	0	16
Fair value, measurement with unobservable inputs reconciliation, recurring basis, assets, unrealized gain (loss)	67	(6)
Purchases (settlements), net	5	50
Transfers out of Level 3	(6)	(135)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	1	4
Non-U.S. Plans \| Automotive Segment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of asset measured on a recurring basis	54	42	40
Realized and unrealized gains (losses), net	2	2
Purchases (settlements), net	6	3
Proceeds from sales	(2)	(2)
Foreign currency exchange rate movements	(6)	1
United States Plans \| Automotive Segment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of asset measured on a recurring basis	29	32	$ 86
Realized and unrealized gains (losses), net	3	0
Purchases (settlements), net	12	48
Proceeds from sales	$ (18)	$ (102)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Foreign Exchange Movements

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Fair value, measurement with unobservable inputs reconciliation, recurring basis, assets, unrealized gain (loss)

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfer of financial instrument classified as an asset into level 3 of the fair value hierarchy.

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-Name Accounting Standards Codification
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Amount of transfers of financial instrument classified as an asset out of level 3 of the fair value hierarchy.

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-Name Accounting Standards Codification
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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Topic 820
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