Equity-Based Awards, Phantom Unit Awards (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Summary of awards activity, equity instruments other than options [Roll Forward]
Common units issued in connection with the vesting of phantom unit awards (in units)		3,479,958		2,485,580		1,761,455
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Cash payments made in connection with DERs		$ 17.7		$ 15.1		$ 11.7
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		7,767,501		5,426,949
Granted (in units)		5,006,181	[1]	4,268,920	[2]	4,508,310	[3]
Vested (in units)		(3,479,958)		(2,490,081)		(1,761,455)
Forfeited (in units)		(482,447)		(256,839)		(406,303)
End of period (in units)		10,333,277		9,289,501		7,767,501
Common units issued in connection with the vesting of phantom unit awards (in units)		2,442,436		1,687,692		1,170,600
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)	[4]	$ 27.65		$ 27.20		$ 33.63
Granted weighted-average grant date fair value per unit (in dollars per unit)	[4]	26.82	[1]	28.83	[2]	21.90	[3]
Vested weighted-average grant date fair value per unit (in dollars per unit)	[4]	28.57		28.30		33.10
Forfeited weighted-average grant date fair value per unit (in dollars per unit)	[4]	26.88		27.60		28.52
Weighted-average grant date fair value per unit, at end of period (in dollars per unit)	[4]	$ 26.97		$ 27.65		$ 27.20
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Aggregate grant date fair value		$ 134.3		$ 123.1		$ 98.7
Estimated forfeiture rate		3.20%		3.80%		3.90%
Cash payments made in connection with DERs		$ 17.7		$ 15.1		$ 11.7
Total intrinsic value of phantom unit awards that vested during period		90.7		$ 69.8		$ 40.9
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 104.2
Recognition period for total unrecognized compensation cost		2 years 1 month 6 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		$ 24.55		$ 21.86
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)		$ 29.22		$ 28.87		$ 27.39
Phantom Unit Awards [Member] | Enterprise [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 84.6

[1] The aggregate grant date fair value of phantom unit awards issued during 2018 was $134.3 million based on a grant date market price of our common units ranging from $25.40 to $29.22 per unit. An estimated annual forfeiture rate of 3.2% was applied to these awards.

[2] The aggregate grant date fair value of phantom unit awards issued during 2017 was $123.1 million based on a grant date market price of our common units ranging from $24.55 to $28.87 per unit. An estimated annual forfeiture rate of 3.8% was applied to these awards.

[3] The aggregate grant date fair value of phantom unit awards issued during 2016 was $98.7 million based on a grant date market price of our common units ranging from $21.86 to $27.39 per unit. An estimated annual forfeiture rate of 3.9% was applied to these awards.

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