Unit-Based Compensation - Summary of Non-Vested Phantom Units (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 13.5		$ 13.5
Unrecognized compensation cost recognition period (in years)			1 year 10 months
Number of Non-vested Units
Non-vested units at beginning of period (in units)			440,047
Forfeited (in units)			(7,303)
Vested (in units)			(113,247)
Non-vested units at end of period (in units)	876,365		876,365
Weighted Average Grant Date Fair Value
Non-vested units at beginning of period (in dollars per unit)			$ 28.87
Forfeited (in dollars per unit)			23.32
Vested (in dollars per unit)			29.29
Non-vested units at end of period (in dollars per unit)	$ 20.20		$ 20.20
Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 3.3		$ 3.3
Unrecognized compensation cost recognition period (in years)			1 year 8 months
Number of Non-vested Units
Non-vested units at beginning of period (in units)			330,440
Forfeited (in units)			(2,441)
Vested (in units)			(122,877)
Non-vested units at end of period (in units)	205,122		205,122
Weighted Average Grant Date Fair Value
Non-vested units at beginning of period (in dollars per unit)			$ 21.27
Forfeited (in dollars per unit)			28.25
Vested (in dollars per unit)			21.57
Non-vested units at end of period (in dollars per unit)	$ 21.01		$ 21.01
Selling, General and Administrative Expenses | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash compensation	$ 3.4	$ 1.5	$ 7.0	$ 3.9
Selling, General and Administrative Expenses | Phantom Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash compensation	$ 0.4	$ 0.7	$ 0.8	$ 1.1