Note 11 - Revenue and Business Segments (Details Textual)	3 Months Ended
Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Number of Reportable Segments	4
Customer Contract Term (Year)	1 year
Capitalized Contract Cost, Impairment Loss	$ 0	$ 0
Number of Operating Segments	5
Prepaid Expenses and Other Current Assets [Member]
Contract with Customer, Asset, after Allowance for Credit Loss, Total	$ 2,200,000		$ 1,700,000
Dedicated [Member]
Depreciation, Depletion and Amortization, Total	$ 9,900,000	7,800,000
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	$ 13,800,000	13,100,000
Intermodal [Member]
Depreciation, Depletion and Amortization, Total	1,400,000	1,300,000
Brokerage [Member]
Depreciation, Depletion and Amortization, Total	$ 362,000	$ 364,000

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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- Definition

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.

+ References

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