Note 3 - Long-term Debt (Details Textual) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Line of Credit Facility, Maximum Borrowing Capacity	$ 30.0
Letters of Credit Outstanding, Amount	16.1	$ 16.1
Line of Credit Facility, Remaining Borrowing Capacity	13.9
Line of Credit Facility, Dividends Payment, Maximum	$ 150.0
Line Of Credit Facility Dividend Restrictions Percentage Of Net Income Limit	25.00%
Line of Credit Facility Dividend Restrictions Percentage of Net Income Limit1	25.00%
Line of Credit Facility, Waiver to Pay Dividends, Maximum	$ 80.0
Credit Facility [Member]
Long-Term Debt, Weighted Average Interest Rate, at Point in Time	8.00%

Line of credit facility dividend restrictions percentage of net income limit.

No definition available.

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Period Type:	instant

- Definition

Line of credit facility dividend restrictions percentage of net income limit.

+ References

No definition available.

+ Details

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Namespace Prefix:	mrtn_
Data Type:	dtr-types:percentItemType
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- Definition

The maximum amount of dividends that can be paid under the credit facility.

+ References

No definition available.

+ Details

Name:	mrtn_LineOfCreditFacilityDividendsPaymentMaximum
Namespace Prefix:	mrtn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The maximum amount for a waiver to pay for dividends as part of a line of credit facility.

+ References

No definition available.

+ Details

Name:	mrtn_LineOfCreditFacilityWaiverToPayDividendsMaximum
Namespace Prefix:	mrtn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=mrtn_CreditFacilityMember
Namespace Prefix:
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Period Type: