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

Name:	us-gaap_PaymentsOfDividendsCommonStock
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:

- Details

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

Note 7 - Dividends (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Aug. 31, 2019
Payments of Ordinary Dividends, Common Stock								$ 7,705	$ 40,448
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	$ 0.027	$ 0.027	$ 0.02	$ 0.02	$ 0.02
Special Dividend [Member]
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.433