Note 10 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%
Deferred Tax Liabilities, Difference in Cumulative Book Value of Depreciation of Property and Equipment	$ 65,000
Deferred Tax Assets, Valuation Allowance, Total	242	$ 385
Liability for Uncertainty in Income Taxes, Current	1,000	900
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	100	100
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total	0	800	$ 100
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	900	900
Tax Credit Carryforward, Amount	10,900
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	92,200
Tax Credit Carryforward, Amount	$ 500
Domestic Tax Authority [Member]
Open Tax Year	2015
Operating Loss Carryforwards, Total	$ 101,900
Operating Loss Carryforwards, Not Subject to Expiration	3,900
Charitable Contributions Carryforward	3,100
Operating Loss Carryforwards, After Charitable Contributions, Not Subject to Expiration	7,000
Deferred Tax Assets Related to State Net Operating Loss Carry Forwards [Member] | State and Local Jurisdiction [Member]
Deferred Tax Assets, Valuation Allowance, Total	300
Transport Financial Services [Member]
Discontinued Operation, Tax Effect of Discontinued Operation, Total	$ 9,500	$ 1,100	$ 600