Financial Instruments and Risk Management - Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value Measurements
Total current derivative contracts, assets	$ 101	$ 57
Total noncurrent derivative contracts, assets	78	16
Total current derivative contracts, liabilities	159	64
Total noncurrent derivative contracts, liabilities	10	1
Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	70	8
Total current derivative contracts, liabilities	104	27
Total noncurrent derivative contracts, liabilities	9	1
Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	12	47
Total noncurrent derivative contracts, assets	78	15
Total current derivative contracts, liabilities	42	18
Total noncurrent derivative contracts, liabilities	1
Other contracts
Fair Value Measurements
Total current derivative contracts, assets	19	2
Total noncurrent derivative contracts, assets		1
Total current derivative contracts, liabilities	13	19
Derivatives Designated As Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	60	13
Total noncurrent derivative contracts, assets	76	16
Total current derivative contracts, liabilities	106	26
Total noncurrent derivative contracts, liabilities	9	1
Derivatives Designated As Hedging Instruments | Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	60	7
Total current derivative contracts, liabilities	100	26
Total noncurrent derivative contracts, liabilities	9	1
Derivatives Designated As Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets		4
Total noncurrent derivative contracts, assets	76	15
Total current derivative contracts, liabilities	5
Derivatives Designated As Hedging Instruments | Other contracts
Fair Value Measurements
Total current derivative contracts, assets		2
Total noncurrent derivative contracts, assets		1
Total current derivative contracts, liabilities	1
Derivatives Not Designated as Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	41	44
Total noncurrent derivative contracts, assets	2
Total current derivative contracts, liabilities	53	38
Total noncurrent derivative contracts, liabilities	1
Derivatives Not Designated as Hedging Instruments | Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	10	1
Total current derivative contracts, liabilities	4	1
Derivatives Not Designated as Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	12	43
Total noncurrent derivative contracts, assets	2
Total current derivative contracts, liabilities	37	18
Total noncurrent derivative contracts, liabilities	1
Derivatives Not Designated as Hedging Instruments | Other contracts
Fair Value Measurements
Total current derivative contracts, assets	19
Total current derivative contracts, liabilities	$ 12	$ 19