CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Revenue - third parties	$ 386,731	$ 307,243	$ 236,719
Revenue - affiliates	762	1,031	917
Total revenue	387,493	308,274	237,636
Costs and expenses:
Cost of sales (excluding depreciation and amortization expense) - affiliates	183,160	162,925	124,242
Depreciation and amortization	88,298	67,930	52,518
Long-lived asset impairment	29,560	1,060	24,976
Selling, general and administrative - affiliates	49,889	39,380	34,830
Interest expense	25,167	30,400	24,037
Other (income) expense, net	(35)	(392)	(314)
Total costs and expenses	376,039	301,303	260,289
Income (loss) before income taxes	11,454	6,971	(22,653)
Income tax provision	945	918	680
Net income (loss)	10,509	6,053	(23,333)
General partner interest in net income (loss)	4,623	3,005	1,091
Common units interest in net income (loss)	5,886	2,723	(19,257)
Subordinated units interest in net income (loss)		$ 325	$ (5,167)
Weighted average common units outstanding:
Basic (in units)	41,371	31,390	21,360
Diluted (in units)	41,382	31,403	21,360
Weighted average subordinated units outstanding:
Basic (in units)		3,747	5,731
Diluted (in units)		3,747	5,731
Income (loss) per common unit:
Basic (in dollars per unit)	$ 0.14	$ 0.09	$ (0.90)
Diluted (in dollars per unit)	$ 0.14	$ 0.09	$ (0.90)
Income (loss) per subordinated unit:
Basic (in dollars per unit)		$ 0.09	$ (0.90)
Diluted (in dollars per unit)		$ 0.09	$ (0.90)
Distributions declared per limited partner unit (in dollars per unit)	$ 2.0000	$ 1.9200	$ 1.8550
Distributions paid per limited partner unit (in dollars per unit)	$ 2.0000	$ 1.9200	$ 1.8550