CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Revenue - third parties	$ 115,717	$ 99,136	$ 346,996	$ 284,589
Revenue - affiliates	91	188	327	603
Total revenue	115,808	99,324	347,323	285,192
Costs and expenses:
Cost of sales (excluding depreciation and amortization expense) - affiliates	51,478	48,652	149,339	138,211
Depreciation and amortization	27,158	21,930	76,894	65,080
Long-lived asset impairment	784		3,249	28,927
Selling, general and administrative - affiliates	16,948	11,762	44,758	37,434
Interest expense	9,735	6,465	27,458	18,746
Other (income) expense, net	(639)	(137)	(8,316)	129
Total costs and expenses	105,464	88,672	293,382	288,527
Income (loss) before income taxes	10,344	10,652	53,941	(3,335)
Provision for income taxes	309	272	1,277	830
Net income (loss)	10,035	10,380	52,664	(4,165)
General partner interest in net income (loss)	1,911	1,343	5,794	3,130
Common units interest in net income (loss)	$ 8,124	$ 9,037	$ 46,870	$ (7,295)
Weighted average common units outstanding:
Basic (in units)	49,409	42,264	47,058	41,070
Diluted (in units)	49,429	42,280	47,072	41,070
Income (loss) per common unit:
Basic (in dollars per unit)	$ 0.16	$ 0.21	$ 1.00	$ (0.18)
Diluted (in dollars per unit)	$ 0.16	$ 0.21	$ 1.00	$ (0.18)
Distributions declared and paid per limited partner unit in respective periods (in dollars per unit)	$ 0.5225	$ 0.5025	$ 1.5525	$ 1.4925