Note 10 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Deferred Tax Liabilities, Difference in Cumulative Book Value of Depreciation of Property and Equipment	$ 84,700
Deferred Tax Assets, Valuation Allowance, Total	(0)	$ 242
Liability for Uncertainty in Income Taxes, Current	600		$ 900
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total		100	$ 100
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 600	900
Open Tax Year	2016 2017 2018 2019 2020
Tax Credit Carryforward, Amount	$ 2,100
State and Local Jurisdiction [Member]
Tax Credit Carryforward, Amount	400
Operating Loss Carryforwards, Total	86,800
Deferred Tax Assets Related to State Net Operating Loss Carry Forwards [Member] | State and Local Jurisdiction [Member]
Deferred Tax Assets, Valuation Allowance, Total	0
Transport Financial Services [Member]
Discontinued Operation, Tax Effect of Discontinued Operation, Total	$ 800	$ 9,500