CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues:
Revenue - third parties	$ 125,352	$ 97,007	$ 231,279	$ 185,452
Revenue - affiliates	101	164	236	416
Total revenue	125,453	97,171	231,515	185,868
Costs and expenses:
Cost of sales (excluding depreciation and amortization expense) - affiliates	50,809	45,446	97,861	89,559
Depreciation and amortization	27,030	22,788	49,736	43,150
Long-lived asset impairment	925	28,122	2,465	28,927
Selling, general and administrative - affiliates	15,203	13,450	27,810	25,672
Interest expense	10,299	6,399	17,723	12,281
Other (income) expense, net	(7,270)	(261)	(7,677)	266
Total costs and expenses	96,996	115,944	187,918	199,855
Income (loss) before income taxes	28,457	(18,773)	43,597	(13,987)
Provision for income taxes	561	277	968	558
Net income (loss)	27,896	(19,050)	42,629	(14,545)
General partner interest in net income (loss)	2,111	692	3,883	1,787
Common units interest in net income (loss)	$ 25,785	$ (19,742)	$ 38,746	$ (16,332)
Weighted average common units outstanding:
Basic (in units)	49,409	42,264	45,863	40,467
Diluted (in units)	49,424	42,264	45,874	40,467
Income (loss) per common unit:
Basic (in dollars per unit)	$ 0.52	$ (0.47)	$ 0.84	$ (0.40)
Diluted (in dollars per unit)	$ 0.52	$ (0.47)	$ 0.84	$ (0.40)
Distributions declared and paid per limited partner unit in respective periods (in dollars per unit)	$ 0.5175	$ 0.4975	$ 1.0300	$ 0.9900