Note 2 - Revenues - Summary of Changes in Balances of Deferred Costs to Obtain and Fulfill Contracts (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)
Costs to Obtain Contracts [Member]
Balances	$ 1,413
Costs deferred	99
Amortization	(242)
Balances	1,270
Costs to Fulfill Contracts [Member]
Balances	606
Costs deferred	63
Amortization	(122)
Balances	$ 547

Represents information about deferred capitalized contract cost.

No definition available.

Name:	mrin_DeferredCapitalizedContractCost
Namespace Prefix:	mrin_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

+ Details

Name:	us-gaap_CapitalizedContractCostAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

+ Details

Name:	us-gaap_CapitalizedContractCostNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_CapitalizedContractCostAxis=mrin_CostsToObtainContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CapitalizedContractCostAxis=mrin_CostsToFulfillContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: