Equity-Based Awards, Restricted Unit Awards (Details) - Restricted Common Unit Awards [Member] - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
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)				1,960,520
Vested (in units)				(1,214,178)
Forfeited (in units)				(41,774)
End of period (in units)		704,568		704,568
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]			$ 27.88
Vested weighted-average grant date fair value per unit (in dollars per unit)	[1]			27.45
Forfeited weighted-average grant date fair value per unit (in dollars per unit)	[1]			28.46
Weighted-average grant date fair value per unit, at end of period (in dollars per unit)	[1]	$ 28.58		$ 28.58
Summary of awards activity, equity instruments other than options, additional disclosures [Abstract]
Cash distributions paid to restricted common unitholders		$ 0.3	$ 0.8	$ 1.4	$ 3.2
Total intrinsic value of our restricted common unit awards that vested during period		0.7	$ 1.5	28.0	$ 66.9
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		1.9		1.9
Enterprise [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost		$ 1.4		$ 1.4

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