Note 15 - Revenue and Business Segments (Details Textual) $ in Thousands	12 Months Ended
Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Number of Operating Segments	5
Number of Reportable Segments	4
Customer Contract Term (Year)	1 year
Capitalized Contract Cost, Impairment Loss	$ 0	$ 0
Prepaid Expenses and Other Current Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Total	2,700	2,200
Dedicated [Member]
Depreciation, Depletion and Amortization, Total	$ 45,600	43,000	$ 41,400
Dedicated [Member] \| Minimum [Member]
Customer Contract Term (Year)	3 years
Dedicated [Member] \| Maximum [Member]
Customer Contract Term (Year)	5 years
Truckload [Member]
Depreciation, Depletion and Amortization, Total	$ 56,400	52,100	54,700
Intermodal [Member]
Depreciation, Depletion and Amortization, Total	7,500	6,300	5,600
Brokerage [Member]
Depreciation, Depletion and Amortization, Total	$ 1,500	$ 1,200	$ 1,200

Duration of customer contracts.

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- Definition

Amount of impairment loss for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

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-Publisher FASB
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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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