Segment Reporting - Identifiable Assets by Industry Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Segment Reconciliation [Abstract]
Total assets	$ 253,656	$ 330,842
Operating Segments
Segment Reconciliation [Abstract]
Total assets	253,656	330,842
Operating Segments | Marketing
Segment Reconciliation [Abstract]
Total assets	81,887	141,402
Operating Segments | Transportation
Segment Reconciliation [Abstract]
Total assets	56,933	58,483
Cash and other
Segment Reconciliation [Abstract]
Total assets	$ 114,836	$ 130,957