Quarterly Financial Information (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Total revenues	$ 751,222	$ 915,719	$ 970,337	$ 864,610	$ 833,558	$ 874,336	$ 877,699	$ 821,535	$ 3,501,888	$ 3,407,128	$ 3,474,920
Total operating costs and expenses	729,194	899,001	952,864	846,327	823,045	895,550	894,688	835,372	3,427,386	3,448,655	3,525,408
Operating Income (Loss)	22,028	16,718	17,473	18,283	10,513	(21,214)	(16,989)	(13,837)	74,502	(41,527)	(50,488)
Net income (loss)	20,638	16,250	17,060	17,845	10,156	(21,180)	(16,956)	(13,814)	71,793	(41,794)	(50,214)
Earnings Per Share [Abstract]
Net income attributable to partners	18,819	12,265	10,975	10,933	8,528				52,992	8,528
Earnings Per Share, Basic	$ 0.40	$ 0.27	$ 0.24	$ 0.24	$ 0.19
Earnings Per Share, Diluted	$ 0.40	$ 0.27	$ 0.24	$ 0.24	$ 0.19
Earnings Per Share, Basic and Diluted	$ 0.40	$ 0.27	$ 0.24	$ 0.24	$ 0.19
Weighted Average Number of Shares Outstanding, Basic	23,795	22,811	22,811	22,811	22,811
Weighted Average Number of Shares Outstanding, Diluted	23,861	22,883	22,861	22,815	22,813
Weighted Average Number of Shares Outstanding, Basic and Diluted	22,811	22,811	22,811	22,811	22,811
Logistics Segment [Member]
Condensed Financial Statements, Captions [Line Items]
Total revenues		35,600	34,981	32,757	26,721	1,670	1,299	1,139
Total operating costs and expenses		22,839	23,564	21,354	20,783	27,081	22,540	19,538
Operating Income (Loss)		12,761	11,417	11,403	5,938	(25,411)	(21,241)	(18,399)
Net income (loss)		12,265	10,975	10,933	5,549	(25,406)	(21,237)	(18,397)
Wholesale Segment [Member]
Condensed Financial Statements, Captions [Line Items]
Total revenues		880,119	935,356	831,853	806,837	872,666	876,400	820,396
Total operating costs and expenses		876,162	929,300	824,973	802,262	868,469	872,148	815,834
Operating Income (Loss)		3,957	6,056	6,880	4,575	4,197	4,252	4,562
Net income (loss)		$ 3,985	$ 6,085	$ 6,912	$ 4,607	$ 4,226	$ 4,281	$ 4,583