Equity-Based Awards, Restricted Unit Awards (Details) - Restricted Common Unit Awards [Member] - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rate of restricted common unit awards		25.00%		25.00%
Summary of awards activity, equity instruments other than options [Roll Forward]
Beginning of period (in units)				682,294
Vested (in units)				(668,470)
Forfeited (in units)				(1,250)
End of period (in units)		12,574		12,574
Restricted 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)	[1]			$ 28.61
Vested weighted-average grant date fair value per unit (in dollars per unit)	[1]			28.56
Forfeited weighted-average grant date fair value per unit (in dollars per unit)	[1]			31.07
Weighted-average grant date fair value per unit, at end of period (in dollars per unit)	[1]	$ 30.92		$ 30.92
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Cash distributions paid to restricted common unitholders		$ 0.0	$ 0.3	$ 0.3	$ 1.1
Total intrinsic value of our restricted common unit awards that vested during period		$ 0.1	$ 0.5	$ 18.6	$ 27.3

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