Segment Reporting - Information Concerning Business Activities (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment									3
Revenues	$ 249,755	$ 266,904	$ 152,286	$ 353,477	$ 431,339	$ 450,307	$ 484,433	$ 445,168	$ 1,022,422	$ 1,811,247	$ 1,750,213
Operating earnings (losses)									(5,747)	7,800	1,408
Depreciation and amortization									18,573	16,641	10,654
Property and equipment additions									5,008	35,743	11,731
Inventory liquidation gains and valuation (losses)	$ (15,000)			$ 24,200	$ 3,700				(15,000)	3,700	(5,400)
Marketing
Segment Reporting Information [Line Items]
Revenues									950,426	1,748,056	1,694,437
Depreciation and amortization									7,421	8,741	6,384
Property and equipment additions									3,130	7,249	1,540
Transportation
Segment Reporting Information [Line Items]
Revenues									71,724	63,191	55,776
Depreciation and amortization									10,963	7,900	4,270
Property and equipment additions									1,355	28,472	10,178
Pipeline and storage
Segment Reporting Information [Line Items]
Revenues									272	0	0
Depreciation and amortization									189	0	0
Property and equipment additions									0	0	0
Operating Segments
Segment Reporting Information [Line Items]
Operating earnings (losses)									4,537	17,998	10,345
Operating Segments | Marketing
Segment Reporting Information [Line Items]
Operating earnings (losses)									2,974	16,099	7,008
Operating Segments | Transportation
Segment Reporting Information [Line Items]
Operating earnings (losses)									1,873	1,899	3,337
Operating Segments | Pipeline and storage
Segment Reporting Information [Line Items]
Operating earnings (losses)									(310)	0	0
Other
Segment Reporting Information [Line Items]
Revenues									0	0	0
Operating earnings (losses)									0	0	0
Depreciation and amortization									0	0	0
Property and equipment additions									$ 523	$ 22	$ 13