Financial Instruments and Risk Management - Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Fair Value Measurements
Total current derivative contracts, assets	$ 48	$ 36
Total noncurrent derivative contracts, assets	1
Total current derivative contracts, liabilities	48	62
Total noncurrent derivative contracts, liabilities	32	64
Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	10	10
Total noncurrent derivative contracts, assets	1
Total current derivative contracts, liabilities	36	53
Total noncurrent derivative contracts, liabilities	2	2
Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	26	21
Total current derivative contracts, liabilities	11	6
Cross-currency and other contracts
Fair Value Measurements
Total current derivative contracts, assets	12	5
Total current derivative contracts, liabilities	1	3
Total noncurrent derivative contracts, liabilities	30	62
Derivatives Designated As Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	12	9
Total noncurrent derivative contracts, assets	1
Total current derivative contracts, liabilities	37	45
Total noncurrent derivative contracts, liabilities	32	64
Derivatives Designated As Hedging Instruments | Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	10	9
Total noncurrent derivative contracts, assets	1
Total current derivative contracts, liabilities	36	42
Total noncurrent derivative contracts, liabilities	2	2
Derivatives Designated As Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	2
Total current derivative contracts, liabilities		2
Derivatives Designated As Hedging Instruments | Cross-currency and other contracts
Fair Value Measurements
Total current derivative contracts, liabilities	1	1
Total noncurrent derivative contracts, liabilities	30	62
Derivatives Not Designated as Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	36	27
Total current derivative contracts, liabilities	11	17
Derivatives Not Designated as Hedging Instruments | Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets		1
Total current derivative contracts, liabilities		11
Derivatives Not Designated as Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	24	21
Total current derivative contracts, liabilities	11	4
Derivatives Not Designated as Hedging Instruments | Cross-currency and other contracts
Fair Value Measurements
Total current derivative contracts, assets	$ 12	5
Total current derivative contracts, liabilities		$ 2