UNAUDITED CONDENSED STATEMENTS OF CONSOLIDATED EQUITY (USD $) In Millions, unless otherwise specified	Total	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]	Limited Partners [Member]
Balance at Dec. 31, 2011	$ 12,219.3	$ (351.4)	$ 105.9	$ 12,464.8
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	1,810.6	0	6.2	1,804.4
Cash distributions paid to limited partners	(1,613.4)	0	0	(1,613.4)
Cash distributions paid to noncontrolling interests	(11.3)	0	(11.3)	0
Cash contributions from noncontrolling interests	6.5	0	6.5	0
Net cash proceeds from the issuance of common units	658.6	0	0	658.6
Amortization of fair value of equity-based awards	45.9	0	0	45.9
Cash flow hedges	(40.4)	(40.4)	0	0
Other	(17.9)	3.5	1.0	(22.4)
Balance at Sep. 30, 2012	13,057.9	(388.3)	108.3	13,337.9
Balance at Dec. 31, 2012	13,296.0	(370.4)	108.3	13,558.1
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	1,901.4	0	3.4	1,898.0
Cash distributions paid to limited partners	(1,778.3)	0	0	(1,778.3)
Cash distributions paid to noncontrolling interests	(6.4)	0	(6.4)	0
Cash contributions from noncontrolling interests	104.2	0	104.2	0
Net cash proceeds from the issuance of common units	1,134.7	0	0	1,134.7
Amortization of fair value of equity-based awards	53.5	0	0	53.5
Cash flow hedges	20.7	20.7	0	0
Other	(43.6)	0.4	0.6	(44.6)
Balance at Sep. 30, 2013	$ 14,682.2	$ (349.3)	$ 210.1	$ 14,821.4