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, 2016	$ 22,266.0	$ (280.0)	$ 219.0	$ 22,327.0
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	771.0	0.0	10.3	760.7
Cash distributions paid to limited partners	(869.0)	0.0	0.0	(869.0)
Cash payments made in connection with distribution equivalent rights	(3.2)	0.0	0.0	(3.2)
Cash distributions paid to noncontrolling interests	(10.1)	0.0	(10.1)	0.0
Cash contributions from noncontrolling interests	0.2	0.0	0.2	0.0
Net cash proceeds from the issuance of common units	448.8	0.0	0.0	448.8
Common units issued in connection with employee compensation	33.7	0.0	0.0	33.7
Amortization of fair value of equity-based awards	24.8	0.0	0.0	24.8
Cash flow hedges	163.9	163.9	0.0	0.0
Other	(26.1)	(0.1)	1.3	(27.3)
Balance at Mar. 31, 2017	22,800.0	(116.2)	220.7	22,695.5
Balance at Dec. 31, 2017	22,772.4	(171.7)	225.2	22,718.9
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	911.5	0.0	10.8	900.7
Cash distributions paid to limited partners	(918.5)	0.0	0.0	(918.5)
Cash payments made in connection with distribution equivalent rights	(3.9)	0.0	0.0	(3.9)
Cash distributions paid to noncontrolling interests	(15.4)	0.0	(15.4)	0.0
Cash contributions from noncontrolling interests	0.1	0.0	0.1	0.0
Net cash proceeds from the issuance of common units	177.0	0.0	0.0	177.0
Common units issued in connection with employee compensation	39.1	0.0	0.0	39.1
Amortization of fair value of equity-based awards	26.0	0.0	0.0	26.0
Cash flow hedges	10.5	10.5	0.0	0.0
Other	(33.9)	0.0	(9.1)	(24.8)
Balance at Mar. 31, 2018	$ 22,964.9	$ (161.2)	$ 211.6	$ 22,914.5