Divestitures (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
Proceeds from Sales of Producing Properties, Acreage and Other Assets	$ 458	$ 144
Book Value of Assets Held for Sale	55
Asset Retirement Obligations	$ 14

Amount of asset retirement obligations settled through noncash transactions. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Name:	us-gaap_SettlementOfAssetRetirementObligationsThroughNoncashPaymentsAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration