Impairments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Property, Plant and Equipment [Line Items]
Impairment of oil and natural gas properties	$ 0	$ 997
Marketing, gathering and compression	1,328	$ 942
Transportation [Member] \| Oil [Member]
Property, Plant and Equipment [Line Items]
Marketing, gathering and compression	290
Transportation [Member] \| Natural Gas [Member]
Property, Plant and Equipment [Line Items]
Loss on Contract Termination	$ 103

Cost incurred related to the gas activities, such as transportation, marketing and processing crude oil, natural gas and refined petroleum products.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62136-109447

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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- Definition

The loss recognized on termination of a contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 912
-SubTopic 275
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68065670&loc=d3e54681-109401

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The excess of unamortized costs capitalized within a cost center, less related deferred income taxes, over the cost center ceiling limitation, which is charged to expense for oil and gas producing companies that use full cost method of accounting for investments in oil and gas producing properties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10(c)(4)(ii))
-URI http://asc.fasb.org/extlink&oid=50486907&loc=d3e511914-122862

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section S99
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27015634&loc=d3e516453-122869

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