Equity-Based Awards, Phantom Unit Awards (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Cash payments made in connection with DERs		$ 3.9	$ 3.2
Phantom Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate of phantom unit awards		25.00%
Summary of awards activity, equity instruments other than options [Roll Forward]
Beginning of period (in units)		9,289,501
Granted (in units)	[1]	4,940,081
Vested (in units)		(3,170,861)
Forfeited (in units)		(74,656)
End of period (in units)		10,984,065
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]	$ 27.65
Granted weighted-average grant date fair value per unit (in dollars per unit)	[1],[2]	26.81
Vested weighted-average grant date fair value per unit (in dollars per unit)	[2]	28.64
Forfeited weighted-average grant date fair value per unit (in dollars per unit)	[2]	26.98
Weighted-average grant date fair value per unit, at end of period (in dollars per unit)	[2]	$ 26.99
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Aggregate grant date fair value		$ 132.4
Estimated forfeiture rate		3.20%
Cash payments made in connection with DERs		$ 3.9	3.2
Total intrinsic value of phantom unit awards that vested during period		82.0	$ 63.2
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 187.5
Recognition period for total unrecognized compensation cost		2 years 4 months 24 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)		$ 25.40
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)		$ 26.81
Phantom Unit Awards [Member] | Enterprise [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 160.7

[1] The aggregate grant date fair value of phantom unit awards issued during 2018 was $132.4 million based on a grant date market price of our common units ranging from $25.40 to $26.81 per unit. An estimated annual forfeiture rate of 3.2% 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.