ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Sales Returns (Details) - Allowance for Sales Returns - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2020	Jun. 30, 2020
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Sales reserves, beginning balance	$ 68	$ 68
Provision related to sales made in current period	1,037	488
Adjustment related to sales made in prior periods	31	4
Actual returns or credits related to current period	(973)	(411)
Actual returns or credits related to prior periods	$ (103)	(67)
Sales reserves, ending balance		$ 82

Actual returns or credits related to the sale of packs and products shipped to the customers in prior periods.

No definition available.

Name:	mtex_ActualReturnsOrCreditsRelatedToPriorPeriods
Namespace Prefix:	mtex_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, charged to costs and expenses.

+ References

No definition available.

+ Details

Name:	mtex_ValuationAllowancesAndReservesChargedToCostAndExpenseCurrentYearSales
Namespace Prefix:	mtex_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total of the deductions in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, representing receivables written off as uncollectible and portions of the reserves utilized, respectively.

+ References

No definition available.

+ Details

Name:	mtex_ValuationAllowancesAndReservesDeductionsCurrentYearReturns
Namespace Prefix:	mtex_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_MovementInValuationAllowancesAndReservesRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) in valuation and qualifying accounts and reserves from adjustment.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

+ Details

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

- Definition

Amount of valuation and qualifying accounts and reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

+ Details

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

- Details

Name:	us-gaap_ValuationAllowancesAndReservesTypeAxis=us-gaap_SalesReturnsAndAllowancesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: