Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Goodwill, Impairment Loss									$ 370us-gaap_GoodwillImpairmentLoss	$ 0us-gaap_GoodwillImpairmentLoss	$ 0us-gaap_GoodwillImpairmentLoss
Operating revenues	1,427us-gaap_Revenues	1,483us-gaap_Revenues	1,178us-gaap_Revenues	863us-gaap_Revenues	677us-gaap_Revenues	665us-gaap_Revenues	639us-gaap_Revenues	540us-gaap_Revenues	4,951us-gaap_Revenues	2,521us-gaap_Revenues	2,000us-gaap_Revenues
Operating income (loss)	(218)us-gaap_OperatingIncomeLoss	144us-gaap_OperatingIncomeLoss	35us-gaap_OperatingIncomeLoss	22us-gaap_OperatingIncomeLoss	12us-gaap_OperatingIncomeLoss	24us-gaap_OperatingIncomeLoss	34us-gaap_OperatingIncomeLoss	(15)us-gaap_OperatingIncomeLoss	(17)us-gaap_OperatingIncomeLoss	55us-gaap_OperatingIncomeLoss	30us-gaap_OperatingIncomeLoss
Net (loss) income attributable to Regency Energy Partners LP	$ (261)us-gaap_NetIncomeLoss	$ 103us-gaap_NetIncomeLoss	$ (8)us-gaap_NetIncomeLoss	$ 9us-gaap_NetIncomeLoss	$ (1)us-gaap_NetIncomeLoss	$ 39us-gaap_NetIncomeLoss	$ 10us-gaap_NetIncomeLoss	$ (29)us-gaap_NetIncomeLoss	$ (157)us-gaap_NetIncomeLoss	$ 19us-gaap_NetIncomeLoss	$ 32us-gaap_NetIncomeLoss
Basic net (loss) income per common unit	$ (0.67)	$ 0.23	$ (0.05)	$ 0.00	$ (0.03)	$ 0.16	$ 0.07	$ (0.06)
Diluted net (loss) income per common unit	$ (0.67)	$ 0.23	$ (0.05)	$ 0.00	$ (0.03)	$ 0.05	$ 0.07	$ (0.06)

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Per unit of ownership amount after tax of income (loss) before extraordinary items available to limited partnership (LP) unit-holder and units that would have been outstanding assuming the issuance of limited partner units for dilutive potential units outstanding.

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Per unit of ownership amount after tax of income (loss) before extraordinary items available to outstanding limited partnership (LP) unit-holder.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The net result for the period of deducting operating expenses from operating revenues.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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