Financial Instruments and Risk Management - Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value Measurements
Total current derivative contracts, assets	$ 133	$ 82
Total noncurrent derivative contracts, assets	43	8
Total current derivative contracts, liabilities	52	84
Total noncurrent derivative contracts, liabilities	4	10
Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	115	50
Total noncurrent derivative contracts, assets	17
Total current derivative contracts, liabilities	33	17
Total noncurrent derivative contracts, liabilities		10
Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	14	30
Total noncurrent derivative contracts, assets	26	8
Total current derivative contracts, liabilities	15	63
Total noncurrent derivative contracts, liabilities	4
Other contracts
Fair Value Measurements
Total current derivative contracts, assets	4	2
Total current derivative contracts, liabilities	4	4
Derivatives Designated As Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	118	53
Total noncurrent derivative contracts, assets	43	8
Total current derivative contracts, liabilities	35	17
Total noncurrent derivative contracts, liabilities		8
Derivatives Designated As Hedging Instruments | Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	115	50
Total noncurrent derivative contracts, assets	17
Total current derivative contracts, liabilities	33	17
Total noncurrent derivative contracts, liabilities		8
Derivatives Designated As Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	3	3
Total noncurrent derivative contracts, assets	26	8
Total current derivative contracts, liabilities	2
Derivatives Not Designated as Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	15	29
Total current derivative contracts, liabilities	17	67
Total noncurrent derivative contracts, liabilities	4	2
Derivatives Not Designated as Hedging Instruments | Commodity contracts
Fair Value Measurements
Total noncurrent derivative contracts, liabilities		2
Derivatives Not Designated as Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	11	27
Total current derivative contracts, liabilities	13	63
Total noncurrent derivative contracts, liabilities	4
Derivatives Not Designated as Hedging Instruments | Other contracts
Fair Value Measurements
Total current derivative contracts, assets	4	2
Total current derivative contracts, liabilities	$ 4	$ 4