Financial Instruments and Risk Management - Fair Value (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Fair Value Measurements
Total current derivative contracts, assets	$ 27	$ 21
Total noncurrent derivative contracts, assets	4	3
Total current derivative contracts, liabilities	14	50
Total noncurrent derivative contracts, liabilities	$ 29	31
Discount factor	12 month LIBOR
Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	$ 14	10
Total noncurrent derivative contracts, assets	4	1
Total current derivative contracts, liabilities	9	17
Total noncurrent derivative contracts, liabilities		8
Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	9	8
Total current derivative contracts, liabilities	5	33
Interest rate and other contracts
Fair Value Measurements
Total current derivative contracts, assets	4	3
Total noncurrent derivative contracts, assets		2
Total noncurrent derivative contracts, liabilities	29	23
Derivatives Designated As Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	13	8
Total noncurrent derivative contracts, assets	4	1
Total current derivative contracts, liabilities	6	12
Total noncurrent derivative contracts, liabilities	29	8
Derivatives Designated As Hedging Instruments | Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	10	6
Total noncurrent derivative contracts, assets	4	1
Total current derivative contracts, liabilities	6	12
Total noncurrent derivative contracts, liabilities		8
Derivatives Designated As Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	3	2
Derivatives Designated As Hedging Instruments | Interest rate and other contracts
Fair Value Measurements
Total noncurrent derivative contracts, liabilities	29
Derivatives Not Designated As Hedging Instruments
Fair Value Measurements
Total current derivative contracts, assets	14	13
Total noncurrent derivative contracts, assets		2
Total current derivative contracts, liabilities	8	38
Total noncurrent derivative contracts, liabilities		23
Derivatives Not Designated As Hedging Instruments | Commodity contracts
Fair Value Measurements
Total current derivative contracts, assets	4	4
Total current derivative contracts, liabilities	3	5
Derivatives Not Designated As Hedging Instruments | Foreign currency contracts
Fair Value Measurements
Total current derivative contracts, assets	6	6
Total current derivative contracts, liabilities	5	33
Derivatives Not Designated As Hedging Instruments | Interest rate and other contracts
Fair Value Measurements
Total current derivative contracts, assets	$ 4	3
Total noncurrent derivative contracts, assets		2
Total noncurrent derivative contracts, liabilities		$ 23