Segment Information (Financial Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total revenues	$ 569,261	$ 680,670	$ 1,615,902	$ 2,023,970
Operating Income (Loss)	13,271	18,424	43,056	41,454
Nonoperating Income (Expense)	(6,131)	(6,188)	(19,701)	(16,365)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	7,140	12,236	23,355	25,089
Depreciation and amortization	10,579	8,963	29,470	25,816
Payments to Acquire Productive Assets	8,530	11,558	24,618	53,708
Assets	582,730	643,385	582,730	643,385	$ 610,222
Logistics Segment [Member]
Segment Reporting Information [Line Items]
Revenues: Affiliate	42,319	46,669	126,288	117,723
Revenues: Third-party	814	787	2,181	2,089
Total revenues	43,133	47,456	128,469	119,812
Depreciation and amortization	8,581	7,817	25,083	22,486
Payments to Acquire Productive Assets	7,623	10,700	22,310	48,804
Assets	413,135	410,419	413,135	410,419
Wholesale Segment [Member]
Segment Reporting Information [Line Items]
Revenues: Affiliate	140,835	170,290	386,813	489,526
Revenues: Third-party	385,293	462,924	1,100,620	1,414,632
Total revenues	526,128	633,214	1,487,433	1,904,158
Depreciation and amortization	1,998	1,146	4,387	3,330
Payments to Acquire Productive Assets	907	858	2,308	4,904
Assets	152,578	158,680	152,578	158,680
Operating Segments [Member] | Logistics Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	8,694	13,149	25,671	21,413
Operating Segments [Member] | Wholesale Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	8,366	8,515	27,116	29,675
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	(3,789)	(3,240)	(9,731)	(9,634)
Assets	$ 17,017	$ 74,286	$ 17,017	$ 74,286