Segment Information (Financial Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 604,692	$ 468,039
Operating Income (Loss)	26,362	13,188
Nonoperating Income (Expense)	(6,586)	(7,170)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	19,776	6,018
Depreciation and amortization	9,732	9,338
Payments to Acquire Productive Assets	5,470	8,356
Assets	579,478	596,048	$ 580,854
Logistics Segment [Member]
Segment Reporting Information [Line Items]
Revenues: Affiliate	49,637	40,916
Revenues: Third-party	619	690
Total revenues	50,256	41,606
Depreciation and amortization	8,581	8,155
Payments to Acquire Productive Assets	5,451	7,984
Assets	411,214	417,212
Wholesale Segment [Member]
Segment Reporting Information [Line Items]
Revenues: Affiliate	140,907	108,541
Revenues: Third-party	413,529	317,892
Total revenues	554,436	426,433
Depreciation and amortization	1,151	1,183
Payments to Acquire Productive Assets	19	372
Assets	145,445	151,323
Operating Segments [Member] | Logistics Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	15,030	5,913
Operating Segments [Member] | Wholesale Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	14,974	9,953
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating Income (Loss)	(3,642)	(2,678)
Assets	$ 22,819	$ 27,513