Segment Reporting - Identifiable Assets by Industry Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Segment Reconciliation [Abstract]
Total assets	$ 470,117	$ 374,703
Operating segments
Segment Reconciliation [Abstract]
Total assets	470,117	374,703
Operating segments | Crude Oil Marketing
Segment Reconciliation [Abstract]
Total assets	260,844	162,770
Operating segments | Transportation
Segment Reconciliation [Abstract]
Total assets	65,608	67,167
Operating segments | Pipeline and storage
Segment Reconciliation [Abstract]
Total assets	25,363	25,569
Cash and other
Segment Reconciliation [Abstract]
Total assets	$ 118,302	$ 119,197