Cash Deposits and Other Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Insurance collateral deposits	$ 707	$ 1,233
Excess loss fund	521	943
Accumulated interest income	340	609
State collateral deposits	39	37
Materials and supplies	540	477
Total cash deposits and other assets	$ 2,147	$ 3,299