Acquisiitions (Proforma Financial Results - Prize, 2012 East Texas Acquisition And 2013 East Texas Acquisition) (Details) (Prize, 2012 East Texas Acquisition And 2013 East Texas Acquisition [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total revenues, Proforma	$ 485,284	$ 476,345
Operating income, Proforma	115,104	104,327
Net income (loss), Proforma	$ 66,068	$ 107,238
Unitholders' (basic) (in dollars per unit), Proforma	$ 0.34	$ 0.75
Unitholders' (diluted) (in dollars per unit), Proforma	$ 0.34	$ 0.73
Limited Partners-Affiliated - Subordinated [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Unitholders' (basic and diluted) (in dollars per unit), Proforma		$ 0.78