Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Section S99
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 35
-Paragraph 32
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Investing Activities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
Investing Activities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Jun. 01, 2016	Nov. 01, 2015
Schedule of Equity Method Investments [Line Items]
Impairment of equity-method investments	$ 0	$ 461	$ 112	$ 461
Special distribution from Gulfstream			0	396
Contribution to Gulfstream for repayment of debt			148	0
Impairment of equity-method investments [Member]
Schedule of Equity Method Investments [Line Items]
Impairment of equity-method investments			112	461
Gulfstream Natural Gas System, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity-method investment debt						$ 300	$ 500
Special distribution from Gulfstream					$ 396
Contribution to Gulfstream for repayment of debt			148		$ 248
Central [Member] \| Delaware Basin Gas Gathering System [Member] \| Impairment of equity-method investments [Member]
Schedule of Equity Method Investments [Line Items]
Impairment of equity-method investments		458	59	458
Northeast G And P [Member] \| Appalachia Midstream Investments [Member] \| Equity earnings (losses) [Member]
Schedule of Equity Method Investments [Line Items]
Impairment of equity-method investments		16		16
Northeast G And P [Member] \| Appalachia Midstream Investments [Member] \| Impairment of equity-method investments [Member]
Schedule of Equity Method Investments [Line Items]
Impairment of equity-method investments		$ 3		$ 3
Northeast G And P [Member] \| Appalachia Midstream Investments [Member] \| Other investing income (loss) - net [Member]
Schedule of Equity Method Investments [Line Items]
Gain on sale of an equity-method investment interest	$ 27		27
Northeast G And P [Member] \| Laurel Mountain Midstream, LLC [Member] \| Impairment of equity-method investments [Member]
Schedule of Equity Method Investments [Line Items]
Impairment of equity-method investments			$ 50