Acquisiitions (Proforma Financial Results - 2014 Acquisition And 2013 East Texas Acquisition) (Details) (2014 Acquisition And 2013 East Texas Acquisition [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Total revenues, Proforma	$ 130,188	$ 130,238	$ 386,117	$ 365,978
Operating income, Proforma	25,124	38,052	87,502	86,984
Net income (loss), Proforma	$ 102,097	$ (21,008)	$ 36,133	$ 39,287
Limited Partners - Public And Affiliated Common Units [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Unitholders' (basic) (in dollars per unit), Proforma	$ 1.52	$ (0.56)	$ (2.35)	$ 0.10
Unitholders' (diluted) (in dollars per unit), Proforma	$ 1.09	$ (0.56)	$ (2.35)	$ 0.10