Units Outstanding (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Limited Partners' Capital Account [Abstract]
Units Outstanding, beginning of period (in units)	105,086,799	101,351,749
Options exercised (in units)	86,543	486,017
Units issued (in units)	0	3,249,861
Units forfeited (in units)	0	(828)
Units Outstanding, end of period (in units)	105,173,342	105,086,799