Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Jun. 30, 2016
Fair Value - Other Financial Instruments
Carrying value of debt, net of unamortized discount	$ 8,300	$ 8,300
Midstream
Fair Value - Other Financial Instruments
Net book value of impaired assets	891
Pre-tax impairment charges	841
Impaired proved oil and gas assets - domestic
Fair Value - Other Financial Instruments
Net book value of impaired assets	1,655
Pre-tax impairment charges	1,030
Impaired proved oil and gas assets - international
Fair Value - Other Financial Instruments
Net book value of impaired assets	7,359
Pre-tax impairment charges	4,693
Property, plant, and equipment \| Chemical
Fair Value - Other Financial Instruments
Net book value of impaired assets	124
Pre-tax impairment charges	121
Level 2
Fair Value - Other Financial Instruments
Debt estimated fair value		273
Level 3 \| Midstream
Fair Value - Other Financial Instruments
Assets, Fair value, nonrecurring	50
Level 3 \| Impaired proved oil and gas assets - domestic
Fair Value - Other Financial Instruments
Assets, Fair value, nonrecurring	625
Level 3 \| Impaired proved oil and gas assets - international
Fair Value - Other Financial Instruments
Assets, Fair value, nonrecurring	2,666
Level 3 \| Property, plant, and equipment \| Chemical
Fair Value - Other Financial Instruments
Assets, Fair value, nonrecurring	3
Total Fair Value
Fair Value - Other Financial Instruments
Debt estimated fair value	8,400	9,100
Recurring \| Level 1
Assets:
Commodity derivatives	557	94
Available for sale investment	167
Liabilities:
Commodity derivatives	544	116
Recurring \| Level 2
Assets:
Commodity derivatives	87	31
Liabilities:
Commodity derivatives	404	304
Recurring \| Netting and Collateral
Assets:
Commodity derivatives	(535)	(85)
Liabilities:
Commodity derivatives	(525)	(100)
Recurring \| Total Fair Value
Assets:
Commodity derivatives	109	40
Available for sale investment	167
Liabilities:
Commodity derivatives	$ 423	$ 320
Non recurring \| Low end of range
Fair Value - Other Financial Instruments
Risk adjusted discount rate	8.00%
Non recurring \| High end of range
Fair Value - Other Financial Instruments
Risk adjusted discount rate	20.00%

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Net book value of impaired assets

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This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a nonrecurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced.

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Fair value as of the balance sheet date of price risk derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets on the balance sheet.

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