Note 6 - Claims Liabilities (Details Textual) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Sep. 01, 2020	Sep. 01, 2019
Self Insurance Auto Liability Claims Threshold Amount			$ 2,000,000.0	$ 1,000,000.0
Workers Compensation Self Insured Retention	$ 500,000
Workers Compensation Per Occurrence Excess Policy	500,000
Letters of Credit Outstanding, Amount	310,000	$ 310,000
Stop Loss for Self Insurance for Employee Health Claims Per Covered Employee Per Year	400,000
Cargo Loss Coverage [Member]
Per Occurrence Deductibles		10,000
Auto Liability Coverage [Member]
Self Insurance Auto Liability Claims Threshold Amount	2,000,000.0	$ 1,000,000.0
Workers Compensation Coverage [Member]
Letters of Credit Outstanding, Amount	300,000
Certificates of Deposit, at Carrying Value	$ 300,000