Earnings Per Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
BASIC EARNINGS PER UNIT
Net income attributable to limited partners		$ 1,284.7	$ 1,313.2	$ 673.8	$ 900.7	$ 774.0	$ 610.9	$ 653.7	$ 760.7	$ 4,172.4	$ 2,799.3	$ 2,513.1
Undistributed earnings allocated and cash payments on phantom unit awards	[1]									(21.5)	(15.9)	(12.9)
Net income available to common unitholders										$ 4,150.9	$ 2,783.4	$ 2,500.2
Basic weighted-average number of common units outstanding (in units)										2,176.5	2,145.0	2,081.4
Basic earnings per unit (in dollars per unit)		$ 0.59	$ 0.60	$ 0.31	$ 0.41	$ 0.36	$ 0.28	$ 0.30	$ 0.36	$ 1.91	$ 1.30	$ 1.20
DILUTED EARNINGS PER UNIT
Net income attributable to limited partners		$ 1,284.7	$ 1,313.2	$ 673.8	$ 900.7	$ 774.0	$ 610.9	$ 653.7	$ 760.7	$ 4,172.4	$ 2,799.3	$ 2,513.1
Diluted weighted-average number of units outstanding:
Distribution-bearing common units (in units)										2,176.5	2,145.0	2,081.4
Phantom units (in units)	[1]									10.5	9.3	7.7
Total (in units)										2,187.0	2,154.3	2,089.1
Diluted earnings per unit (in dollars per unit)		$ 0.59	$ 0.60	$ 0.31	$ 0.41	$ 0.36	$ 0.28	$ 0.30	$ 0.36	$ 1.91	$ 1.30	$ 1.20

[1] Each phantom unit award includes a DER, which entitles the recipient to receive cash payments equal to the product of the number of phantom unit awards and the cash distribution per unit paid to our common unitholders. Cash payments made in connection with DERs are nonforfeitable. As a result, the phantom units are considered participating securities for purposes of computing basic earnings per unit.