Equity and Distributions (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			9 Months Ended					3 Months Ended			9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended			12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011	Sep. 30, 2012		Sep. 30, 2011	Dec. 31, 2011		Sep. 30, 2012 Cash Distribution [Member]	Jun. 30, 2012 Cash Distribution [Member]	Mar. 31, 2012 Cash Distribution [Member]	Sep. 30, 2012 Cash Distribution [Member]	Sep. 30, 2012 Distribution Reinvestment Plan [Member]	Sep. 30, 2012 Distribution Reinvestment Plan [Member]	Sep. 30, 2012 Enterprise EUPP [Member]	Sep. 30, 2012 Enterprise EUPP [Member]	Sep. 30, 2012 Shelf Registration 2010 [Member]	Sep. 30, 2012 2012 At-the-Market Registration [Member]	Sep. 30, 2012 Common Units (Unrestricted) [Member]	Sep. 30, 2012 Restricted Common Units [Member]	Sep. 30, 2012 Common units [Member]	Dec. 31, 2009 Class B units [Member] TEPPCO Merger [Member]
Summary of changes in outstanding units [Roll Forward]
Beginning Balance (in units)																			877,752,202	3,868,216	881,620,418
Common units issued in connection with underwritten offerings (in units)																			9,200,000	0	9,200,000
Common units issued in connection with at-the-market program (in units)																			1,648,291	0	1,648,291
Common units issued in connection with DRIP and EUPP (in units)																			2,008,266	0	2,008,266
Common units issued in connection with the vesting of unit options (in units)																			201,925	0	201,925
Common units issued in connection with the vesting of restricted common unit awards (in units)				1,264,483															1,264,483	(1,264,483)	0
Common units issued in connection with the vesting of other types of equity-based awards (in units)																			16,667	0	16,667
Restricted common units awards issued (in units)																			0	1,556,038	1,556,038
Forfeiture of restricted common unit awards (in units)																			0	(225,390)	(225,390)
Acquisition and cancellation of treasury units in connection with the vesting of equity-based awards (in units)				382,420															(382,420)	0	(382,420)
Ending Balance (in units)																			891,709,414	3,934,381	895,643,795
Registration Statements and Equity Offerings [Line Items]
Maximum common units authorized for issuance																		$ 1,000
Maximum common units authorized for issuance (in units)													70,000,000	70,000,000	440,879	440,879
Remaining units available for issuance (in units)													24,267,343	24,267,343	328,379	328,379
Gross proceeds from the sale of common units																		87
Net Cash Proceeds from Sale of Common Units [Abstract]
Number of Common Units Issued (in units)													707,245	1,905,797	30,412	102,469	9,200,000	1,648,291
Over-allotment of common units included in offering (in units)																	1,200,000
Offering price of common unit (in dollars per share)																	$ 53.07
Net cash proceeds from issuance of common units				654.8		67.1							35.8	93.8	1.7	5.4	473.3	86.3
Treasury Units [Abstract]
Conversion of restricted units to common units (in units)				1,264,483															1,264,483	(1,264,483)	0
Retention unit awards that vested during the period (in units)				4,100
Acquisition of treasury units in connection with vesting of equity-based awards (in units)				382,420															(382,420)	0	(382,420)
Mergers [Line Items]
Common unit exchange ratio in connection with merger																						1.24
Number of quarters Class B units are not entitled to regular quarterly cash distributions																						4,520,431
Accumulated Other Comprehensive Income (Loss) [Abstract]
Commodity derivative instruments	2.6	[1]		2.6	[1]		(21.4)	[1]
Interest rate derivative instruments	(393.4)	[1]		(393.4)	[1]		(329.0)	[1]
Foreign currency translation adjustment	1.7	[2]		1.7	[2]		1.7	[2]
Pension and postretirement benefit plans	0.8			0.8			(1.7)
Other	0			0			(1)
Total	(388.3)			(388.3)			(351.4)
Components of noncontrolling interests [Abstract]
Joint venture partners	108.3	[3]		108.3	[3]		105.9	[3]
Components of net income attributable to noncontrolling interests [Abstract]
Former owners of Duncan Energy Partners	0		3.6	0		20.9
Joint venture partners	1.1		4.5	6.2		15.8
Total	1.1		8.1	6.2		36.7
Cash distributions paid to noncontrolling interests:
Former owners of Duncan Energy Partners				0		32.9
Joint venture partners				11.3		19.1
Total				11.3		52.0
Cash contributions from noncontrolling interests:
Former owners of Duncan Energy Partners				0		2.6
Joint venture partners				6.5		2.1
Total				$ 6.5		$ 4.7
Distributions to Partners [Abstract]
Distribution Per Common Unit (in dollars per unit)									$ 0.6500	$ 0.6350	$ 0.6275
Record Date									Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012
Payment Date									Nov. 08, 2012	Aug. 08, 2012	May 09, 2012
Number of Designated Units (in units)												26,130,000

[1] See Note 4 for additional information regarding our derivative instruments.

[2] Relates to transactions of a Canadian subsidiary.

[3] Represents third party ownership interests in joint ventures that we consolidate, including Tri-States NGL Pipeline L.L.C., Independence Hub LLC, Rio Grande Pipeline Company and Wilprise Pipeline Company LLC.