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

No definition available.

Name:	mrtn_LineOfCreditFacilityDividendRestrictionsPercentageOfNetIncomeLimit
Namespace Prefix:	mrtn_
Data Type:	num:percentItemType
Balance Type:	na
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

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

+ Details

Name:	us-gaap_CommonStockDividendsPerShareDeclared
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

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

- Details

Name:	us-gaap_DividendsAxis=mrtn_PaidQuarterlyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 6 - Dividends (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Aug. 31, 2019
Payments of Ordinary Dividends, Common Stock					$ 4,398	$ 3,276
Line Of Credit Facility Dividend Restrictions Percentage Of Net Income Limit							25.00%
Line of Credit Facility, Waiver to Pay Dividends, Maximum							$ 65,000
Paid Quarterly [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.04	$ 0.04	$ 0.03	$ 0.03