Fair Value Measurements (Details) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Fair Value - Other Financial Instruments
Debt carrying value	$ 6,900,000,000us-gaap_DebtInstrumentCarryingAmount	$ 6,900,000,000us-gaap_DebtInstrumentCarryingAmount
Asset impairments and related items	324,000,000
Pre-tax impairment of oil and gas properties	310,000,000us-gaap_ImpairmentOfOilAndGasProperties
Level 1
Assets:
Available for sale investment	544,000,000	394,000,000
Fair Value - Other Financial Instruments
Debt estimated fair value	7,200,000,000	7,000,000,000
Investment recorded as available for sale asset, shares owned	71.5
Level 2
Fair Value - Other Financial Instruments
Debt estimated fair value	90,000,000
Total Fair Value
Assets:
Available for sale investment	544,000,000	394,000,000
Recurring \| Level 1
Assets:
Commodity derivatives	360,000,000	712,000,000
Liabilities:
Commodity derivatives	350,000,000	750,000,000
Recurring \| Level 2
Assets:
Commodity derivatives	54,000,000	127,000,000
Liabilities:
Commodity derivatives	233,000,000	246,000,000
Recurring \| Netting and Collateral
Assets:
Commodity derivatives	(331,000,000)	(742,000,000)
Liabilities:
Commodity derivatives	(349,000,000)	(756,000,000)
Recurring \| Total Fair Value
Assets:
Commodity derivatives	83,000,000	97,000,000
Liabilities:
Commodity derivatives	234,000,000	240,000,000
Non recurring \| Proved oil and gas assets - domestic
Fair Value - Other Financial Instruments
Pre-tax impairment of oil and gas properties	160,000,000	2,759,000,000
Non recurring \| Proved oil and gas assets - international
Fair Value - Other Financial Instruments
Pre-tax impairment of oil and gas properties		1,039,000,000
Non recurring \| Property, plant, and equipment \| Chemical
Fair Value - Other Financial Instruments
Pre-tax impairment of oil and gas properties		111,000,000
Non recurring \| Level 3 \| Proved oil and gas assets - domestic
Fair Value - Other Financial Instruments
Carrying value of impaired assets	41,000,000	2,249,000,000
Non recurring \| Level 3 \| Proved oil and gas assets - international
Fair Value - Other Financial Instruments
Carrying value of impaired assets		45,000,000
Non recurring \| Level 3 \| Property, plant, and equipment \| Chemical
Fair Value - Other Financial Instruments
Carrying value of impaired assets		18,000,000
Non recurring \| Net Book Value \| Proved oil and gas assets - domestic
Fair Value - Other Financial Instruments
Carrying value of impaired assets	201,000,000	5,008,000,000
Non recurring \| Net Book Value \| Proved oil and gas assets - international
Fair Value - Other Financial Instruments
Carrying value of impaired assets		1,084,000,000
Non recurring \| Net Book Value \| Property, plant, and equipment \| Chemical
Fair Value - Other Financial Instruments
Carrying value of impaired assets		$ 129,000,000

Carrying value of impaired assets

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Investment recorded as available for sale asset, shares owned.

+ References

No definition available.

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- Definition

The pre-tax charge against earnings resulting from the write down of long lived assets due to the difference between the carrying value and lower fair value, and related items.

+ References

No definition available.

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Value of investment recorded as available for sale asset.

+ References

No definition available.

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Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

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-Subparagraph (SX 210.5-02.22)

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-Publisher SEC

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-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 932

-SubTopic 360

-Section 35

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-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230

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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.

+ References

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

+ References

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