UNAUDITED CONDENSED STATEMENTS OF CONSOLIDATED EQUITY - USD ($) $ in Millions	Total	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]	Limited Partners [Member]
Balance at Dec. 31, 2014	$ 19,692.2	$ (241.6)	$ 1,629.0	$ 18,304.8
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	650.6	0.0	14.5	636.1
Cash distributions paid to limited partners	(703.8)	0.0	0.0	(703.8)
Cash payments made in connection with distribution equivalent rights	(1.2)	0.0	0.0	(1.2)
Cash distributions paid to noncontrolling interests	(16.5)	0.0	(16.5)	0.0
Cash contributions from noncontrolling interests	4.0	0.0	4.0	0.0
Common units issued in connection with Step 2 of Oiltanking acquisition	0.0	0.0	(1,408.7)	1,408.7
Net cash proceeds from the issuance of common units	468.4	0.0	0.0	468.4
Amortization of fair value of equity-based awards	23.3	0.0	0.0	23.3
Cash flow hedges	(21.6)	(21.6)	0.0	0.0
Other	(37.3)	0.0	0.1	(37.4)
Balance at Mar. 31, 2015	20,058.1	(263.2)	222.4	20,098.9
Balance at Dec. 31, 2015	20,501.1	(219.2)	206.0	20,514.3
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	670.2	0.0	9.0	661.2
Cash distributions paid to limited partners	(788.3)	0.0	0.0	(788.3)
Cash payments made in connection with distribution equivalent rights	(2.0)	0.0	0.0	(2.0)
Cash distributions paid to noncontrolling interests	(8.7)	0.0	(8.7)	0.0
Cash contributions from noncontrolling interests	11.1	0.0	11.1	0.0
Net cash proceeds from the issuance of common units	1,011.5	0.0	0.0	1,011.5
Amortization of fair value of equity-based awards	22.3	0.0	0.0	22.3
Cash flow hedges	(49.2)	(49.2)	0.0	0.0
Other	(21.7)	(0.1)	0.0	(21.6)
Balance at Mar. 31, 2016	$ 21,346.3	$ (268.5)	$ 217.4	$ 21,397.4