Segment Reporting - Information Concerning Business Activities (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) segment	Sep. 30, 2020 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			3
Number of operating segments | segment			3
Segment Reporting Information [Line Items]
Revenues	$ 568,181	$ 266,904	$ 1,380,416	$ 772,667
Segment operating earnings (losses)	2,301	6,056	12,487	(10,949)
Depreciation and amortization	4,849	4,859	14,703	13,610
Property and equipment additions	6,327	709	9,929	3,589
Crude Oil Marketing
Segment Reporting Information [Line Items]
Revenues	543,228	245,184	1,310,343	722,546
Depreciation and amortization	1,611	1,836	5,050	5,700
Property and equipment additions	443	684	1,145	2,734
Inventory liquidation gains (losses)	(300)	(12)	10,300	(18,200)
Transportation
Segment Reporting Information [Line Items]
Revenues	24,826	21,720	69,558	50,121
Depreciation and amortization	2,957	3,023	8,895	7,910
Property and equipment additions	4,904	(32)	7,607	332
Pipeline and storage
Segment Reporting Information [Line Items]
Revenues	127	0	515	0
Depreciation and amortization	281	0	758	0
Property and equipment additions	980	0	1,169	0
Operating segments
Segment Reporting Information [Line Items]
Revenues	568,833	266,904	1,381,821	772,667
Segment operating earnings (losses)	5,803	7,461	22,326	(3,919)
Operating segments | Crude Oil Marketing
Segment Reporting Information [Line Items]
Revenues	543,228	245,184	1,310,343	722,546
Segment operating earnings (losses)	4,255	5,869	19,643	(4,952)
Operating segments | Transportation
Segment Reporting Information [Line Items]
Revenues	24,867	21,720	69,670	50,121
Segment operating earnings (losses)	2,264	1,592	4,520	1,033
Operating segments | Pipeline and storage
Segment Reporting Information [Line Items]
Revenues	738	0	1,808	0
Segment operating earnings (losses)	(716)	0	(1,837)	0
Intersegment
Segment Reporting Information [Line Items]
Revenues	(652)	0	(1,405)	0
Intersegment | Crude Oil Marketing
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Intersegment | Transportation
Segment Reporting Information [Line Items]
Revenues	(41)	0	(112)	0
Intersegment | Pipeline and storage
Segment Reporting Information [Line Items]
Revenues	(611)	0	(1,293)	0
Other
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Segment operating earnings (losses)	0	0	0	0
Depreciation and amortization	0	0	0	0
Property and equipment additions	$ 0	$ 57	$ 8	$ 523