Cash Deposits and Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Insurance collateral deposits	$ 1,233	$ 1,453
Excess loss fund	943	1,916
Accumulated interest income	609	788
State collateral deposits	37	57
Materials and supplies	477	443
Total	$ 3,299	$ 4,657