Net Income (Loss) Per Unit (Details) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Employee options [Member]
Potentially dilutive common equity excluded from the dilutive net income (loss)
Potentially dilutive common equity	820	1,214	820	1,214
Unit appreciation rights [Member]
Potentially dilutive common equity excluded from the dilutive net income (loss)
Potentially dilutive common equity	365	345	365	345
Restricted units [Member]
Potentially dilutive common equity excluded from the dilutive net income (loss)
Potentially dilutive common equity	59	104	59	104
Phantom units [Member]
Potentially dilutive common equity excluded from the dilutive net income (loss)
Potentially dilutive common equity	988	920	988	920
Contingent incentive plan unit awards [Member]
Potentially dilutive common equity excluded from the dilutive net income (loss)
Potentially dilutive common equity	39	37	56	49
Series A preferred units [Member]
Potentially dilutive common equity excluded from the dilutive net income (loss)
Potentially dilutive common equity	10,996		11,121