Note 7 - Debt (Details Textual) - USD ($) $ in Thousands			3 Months Ended				9 Months Ended	12 Months Ended
	Oct. 23, 2020	Sep. 23, 2020	Mar. 31, 2023	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Dec. 31, 2022	Sep. 23, 2021	Sep. 30, 2020	Aug. 31, 2015
Long-Term Line of Credit			$ 0
Letters of Credit Outstanding, Amount			23,900					$ 23,900
Repayments of Lines of Credit			10,665	$ 46,899
Transport Financial Services [Member] | Discontinued Operations, Disposed of by Sale [Member]
Discontinued Operation, Amount of Continuing Cash Flows after Disposal						$ (35,600)
Interest Rate Swap [Member]
Derivative, Fixed Interest Rate											4.20%
Variable Rate Note [Member]
Debt Instrument, Face Amount											$ 28,000
Lenders [Member]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Percent of Eligible Accounts Receivable								87.50%
Percent of Appraised Net Orderly Liquidation, Value of Eligible Revenue Equipment								85.00%
Percent of Net Book Value of Eligible Revenue Equipment								100.00%
Line of Credit Facility, Availability as Percentage of Revolver Commitment								60.00%
Line of Credit Facility, Revolver Commitment, Amount								$ 65,000
Letters of Credit Outstanding, Amount			23,900
Line of Credit Facility, Remaining Borrowing Capacity			86,100
Fixed Charge Coverage Requirement			0	$ 0
Debt, Secured with a Cross Default Feature			10,400
Lenders [Member] | Federal Funds Rate [Member] | Base Rate Loans [Member]
Debt Instrument, Basis Spread on Variable Rate							0.50%
Lenders [Member] | Applicable Margin [Member] | Base Rate Loans [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Lenders [Member] | Applicable Margin [Member] | Base Rate Loans [Member] | Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Lenders [Member] | Applicable Margin [Member] | LIBOR Loans [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Lenders [Member] | Applicable Margin [Member] | LIBOR Loans [Member] | Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Lenders [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 110,000
Line of Credit Facility, Maximum Increase in Borrowing Capacity	75,000
Lenders [Member] | Revolving Credit Facility [Member] | Base Rate Loans [Member]
Long-Term Line of Credit			0
Lenders [Member] | Revolving Credit Facility [Member] | LIBOR Loans [Member]
Long-Term Line of Credit			0
Lenders [Member] | Letter of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity	105,000
Line of Credit Facility, Borrowing Capacity, Percentage of Aggregate Commitments	$ 10,000
Lenders [Member] | Swing Line Sub Facility [Member]
Percent of Aggregate Commitments under Credit Facility	10.00%
TBK Bank [Member] | Draw Note [Member]
Line of Credit Facility, Maximum Borrowing Capacity										$ 45,000
Debt Instrument, Collateral Amount									$ 60,000
Repayments of Lines of Credit					$ 31,000
Long-term Debt, Total			$ 0
TBK Bank [Member] | London Interbank Offered Rate LIBOR 1 [Member] | Draw Note [Member]
Debt Instrument, Basis Spread on Variable Rate		1.50%
TBK Bank [Member] | London Interbank Offered Rate LIBOR 1 [Member] | Draw Note [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate		0.25%