Note 14 - Deferred Compensation Plan (Details Textual)	Dec. 31, 2017 shares
Deferred Compensation Plan Number Of Common Shares Credited To Account Balances	175,449

Deferred compensation plan number of common shares credited to account balances.

No definition available.

Name:	mrtn_DeferredCompensationPlanNumberOfCommonSharesCreditedToAccountBalances
Namespace Prefix:	mrtn_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant