Equity-Based Compensation (Phantom Units) (Details) (Phantom Units [Member], USD $)	3 Months Ended
	Mar. 31, 2012
Phantom Units [Member]
Outstanding at the beginning of the period, Units	1,086,393
Service condition grants, Units	4,000
Vested service condition, Units	(13,039)
Forfeited or expired, Units	(15,950)
Outstanding at the end of period, Units	1,061,404
Outstanding at the beginning of the period, Weighted Average Grant Date Fair Value	$ 24.51
Service condition grants, Weighted Average Grant Date Fair Value	$ 26.24
Vested service condition, Weighted Average Grant Date Fair Value	$ 20.65
Forfeited service condition, Weighted Average Grant Date Fair Value	$ 24.81
Outstanding at the end of the period, Weighted Average Grant Date Fair Value	$ 24.56