Equity-based Awards, Phantom Unit Awards (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Cash payments made in connection with DERs		$ 2.0	$ 1.2
Phantom Unit Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate of phantom unit awards (in hundredths)		25.00%
Summary of awards activity, equity instruments other than options [Roll Forward]
Beginning of period (in units)		5,426,949
Granted (in units)	[1]	4,467,730
Vested (in units)		(1,586,493)
Forfeited (in units)		(41,673)
End of period (in units)		8,266,513
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]	$ 33.63
Granted weighted-average grant date fair value per unit (in dollars per unit)	[1],[2]	21.86
Vested weighted-average grant date fair value per unit (in dollars per unit)	[2]	33.56
Forfeited weighted-average grant date fair value per unit (in dollars per unit)	[2]	31.11
Weighted-average grant date fair value per unit, at end of period (in dollars per unit)	[2]	$ 27.29
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Aggregate grant date fair value		$ 97.7
Estimated forfeiture rate (in hundredths)		3.90%
Cash payments made in connection with DERs		$ 2.0	1.2
Total intrinsic value of phantom unit awards that vested during period		36.3	$ 26.6
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 145.2
Recognition period for total unrecognized compensation cost (in years)		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)		$ 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)		$ 21.86
Phantom Unit Awards [Member] | Enterprise [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 133.1

[1] The aggregate grant date fair value of phantom unit awards issued during 2016 was $97.7 million based on a grant date market price of our common units of $21.86 per unit. An estimated annual forfeiture rate of 3.9% 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.