Quarterly Financial Data (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Operating revenues	$ 677	$ 665	$ 639	$ 540	$ 587	$ 527	$ 511	$ 375	$ 2,521	$ 2,000	$ 1,434
Operating income (loss)	12	24	34	(15)	8	5	22	(5)	55	30	40
Net (loss) income attributable to Regency Energy Partners LP	$ (1)	$ 39	$ 10	$ (29)	$ (8)	$ (1)	$ 26	$ 15	$ 19	$ 32	$ 72
Basic net (loss) income per common unit	$ (0.03)	$ 0.16	$ 0.07	$ (0.06)	$ (0.08)	$ (0.04)	$ 0.14	$ 0.15
Diluted net (loss) income per common unit	$ (0.03)	$ 0.05	$ 0.07	$ (0.06)	$ (0.08)	$ (0.04)	$ 0.10	$ 0.14