Equity-Based Awards, Phantom Unit Awards (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Cash payments made in connection with DERs				$ 7.2	$ 5.3
Phantom Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate of phantom unit awards		25.00%		25.00%
Summary of awards activity, equity instruments other than options [Roll Forward]
Beginning of period (in units)				7,767,501
Granted (in units)	[1]			4,224,680
Vested (in units)				(2,355,937)
Forfeited (in units)				(107,145)
End of period (in units)		9,529,099		9,529,099
Phantom units outstanding, weighted-average grant date fair value [Roll Forward]
Weighted-average grant date fair value per unit, at beginning of period (in dollars per unit)	[2]			$ 27.20
Granted weighted-average grant date fair value per unit (in dollars per unit)	[1],[2]			28.86
Vested weighted-average grant date fair value per unit (in dollars per unit)	[2]			28.32
Forfeited weighted-average grant date fair value per unit (in dollars per unit)	[2]			27.74
Weighted-average grant date fair value per unit, at end of period (in dollars per unit)	[2]	$ 27.66		$ 27.66
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Aggregate grant date fair value				$ 121.9
Estimated forfeiture rate				3.80%
Cash payments made in connection with DERs		$ 4.0	$ 3.3	$ 7.2	5.3
Total intrinsic value of phantom unit awards that vested during period		3.1	$ 0.8	66.3	$ 37.1
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		142.0		$ 142.0
Recognition period for total unrecognized compensation cost				2 years 2 months 12 days
Phantom Unit Awards [Member] | Minimum [Member]
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Grant date market price of common units (in dollars per unit)				$ 26.40
Phantom Unit Awards [Member] | Maximum [Member]
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Grant date market price of common units (in dollars per unit)				$ 28.87
Phantom Unit Awards [Member] | Enterprise [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 122.5		$ 122.5

[1] The aggregate grant date fair value of phantom unit awards issued during 2017 was $121.9 million based on a grant date market price of our common units ranging from $26.40 to $ 28.87 per unit. An estimated annual forfeiture rate of 3.8% was applied to these awards.

[2] Determined by dividing the aggregate grant date fair value of awards (before an allowance for forfeitures) by the number of awards issued.