Supplemental Guarantor / Non-Guarantor Financial Information Condensed Consolidated Balance Sheet (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 4,216	$ 3,269	$ 1,402	$ 403
Accounts receivable	30,169	34,071
Intercompany accounts receivable (payable)	0	0
Prepaid and other current assets	3,410	2,644
Total current assets	37,795	39,984
Properties and equipment, net	532,548	536,425
Investments in subsidiaries	0	0
Transportation agreements, net	98,070	101,543
Goodwill	256,498	256,498
Investment in SLC Pipeline	25,427	25,302
Other assets	9,360	7,204
Total assets	959,698	966,956
Current liabilities:
Accounts payable	9,695	11,406
Accrued interest	9,655	8,280
Deferred revenue	3,603	4,032
Accrued property taxes	1,910	2,196
Other current liabilities	2,581	1,777
Total current liabilities	27,444	27,691
Long-term debt	613,195	605,888
Other long-term liabilities	6,195	4,000
Partners' equity	312,864	329,377
Total liabilities and partners’ equity	959,698	966,956
Parent [Member]
Current assets:
Cash and cash equivalents	2	2	2	2
Accounts receivable	0	0
Intercompany accounts receivable (payable)	47,371	17,745
Prepaid and other current assets	42	266
Total current assets	47,415	18,013
Properties and equipment, net	0	0
Investments in subsidiaries	716,967	651,217
Transportation agreements, net	0	0
Goodwill	0	0
Investment in SLC Pipeline	0	0
Other assets	1,757	1,322
Total assets	766,139	670,552
Current liabilities:
Accounts payable	0	0
Accrued interest	9,602	7,498
Deferred revenue	0	0
Accrued property taxes	0	0
Other current liabilities	478	689
Total current liabilities	10,080	8,187
Long-term debt	443,195	332,988
Other long-term liabilities	0	0
Partners' equity	312,864	329,377
Total liabilities and partners’ equity	766,139	670,552
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	4,214	3,267	1,400	401
Accounts receivable	30,169	34,071
Intercompany accounts receivable (payable)	(47,371)	(17,745)
Prepaid and other current assets	3,368	2,378
Total current assets	(9,620)	21,971
Properties and equipment, net	532,548	536,425
Investments in subsidiaries	0	0
Transportation agreements, net	98,070	101,543
Goodwill	256,498	256,498
Investment in SLC Pipeline	25,427	25,302
Other assets	7,603	5,882
Total assets	910,526	947,621
Current liabilities:
Accounts payable	9,695	11,406
Accrued interest	53	782
Deferred revenue	3,603	4,032
Accrued property taxes	1,910	2,196
Other current liabilities	2,103	1,088
Total current liabilities	17,364	19,504
Long-term debt	170,000	272,900
Other long-term liabilities	6,195	4,000
Partners' equity	716,967	651,217
Total liabilities and partners’ equity	910,526	947,621
Eliminations [Member]
Current assets:
Cash and cash equivalents	0	0	0	0
Accounts receivable	0	0
Intercompany accounts receivable (payable)	0	0
Prepaid and other current assets	0	0
Total current assets	0	0
Properties and equipment, net	0	0
Investments in subsidiaries	(716,967)	(651,217)
Transportation agreements, net	0	0
Goodwill	0	0
Investment in SLC Pipeline	0	0
Other assets	0	0
Total assets	(716,967)	(651,217)
Current liabilities:
Accounts payable	0	0
Accrued interest	0	0
Deferred revenue	0	0
Accrued property taxes	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Long-term debt	0	0
Other long-term liabilities	0	0
Partners' equity	(716,967)	(651,217)
Total liabilities and partners’ equity	$ (716,967)	$ (651,217)