Segment Reporting - Identifiable Assets by Industry Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Segment Reconciliation [Abstract]
Total assets	$ 256,460	$ 330,842
Operating Segments
Segment Reconciliation [Abstract]
Total assets	256,460	330,842
Operating Segments | Marketing
Segment Reconciliation [Abstract]
Total assets	119,758	141,402
Operating Segments | Transportation
Segment Reconciliation [Abstract]
Total assets	67,310	58,483
Cash and other
Segment Reconciliation [Abstract]
Total assets	$ 69,392	$ 130,957