Minimum threshold shares scheduled to vest for performance based shares.

No definition available.

Name:	mtrx_MinimumThresholdSharesScheduledToVestForPerformanceBasedShares
Namespace Prefix:	mtrx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Payout as percentage of original award maximum.

+ References

No definition available.

+ Details

Name:	mtrx_PayoutAsPercentageOfOriginalAwardMaximum
Namespace Prefix:	mtrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Payout as percentage of original award minimum.

+ References

No definition available.

+ Details

Name:	mtrx_PayoutAsPercentageOfOriginalAwardMinimum
Namespace Prefix:	mtrx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award deferred grants in period.

+ References

No definition available.

+ Details

Name:	mtrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardDeferredGrantsInPeriod
Namespace Prefix:	mtrx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award deferred shares vested and released.

+ References

No definition available.

+ Details

Name:	mtrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardDeferredSharesVestedAndReleased
Namespace Prefix:	mtrx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award deferred shares vested and released weighted average grant date fair value.

+ References

No definition available.

+ Details

Name:	mtrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardDeferredSharesVestedAndReleasedWeightedAverageGrantDateFairValue
Namespace Prefix:	mtrx_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Share based compensation arrangement by share based payment award deferred weighted average grant date fair value.

+ References

No definition available.

+ Details

Name:	mtrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardDeferredWeightedAverageGrantDateFairValue
Namespace Prefix:	mtrx_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Share Based Compensation Arrangement By Share Based Payment Award Fair Value Method Number of Simulations Used

+ References

No definition available.

+ Details

Name:	mtrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueMethodNumberofSimulationsUsed
Namespace Prefix:	mtrx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Share based compensation arrangement by share based payment award installment period for vesting.

+ References

No definition available.

+ Details

Name:	mtrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardInstallmentPeriodForVesting
Namespace Prefix:	mtrx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 740
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120384911&loc=d3e23163-113944

+ Details

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

- Definition

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of noncash expense for share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

+ Details

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

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Number of shares authorized for issuance under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis=mtrx_EmployeeAwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis=mtrx_DirectorAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=mtrx_MarketBasedAwardsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=mtrx_VestIn2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=mtrx_VestIn2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=mtrx_VestIn2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stock-Based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 9,877	$ 11,908	$ 8,618
Unrecognized stock-based compensation expense	$ 11,900
Weighted average period	1 year 7 months 6 days
Excess tax expense (benefits) related to stock compensation vesting	$ 200	(300)	500
Share awards authorized	1,600,000
Share available for grant	1,473,424
Common stock grant expiration term	10 years
Total intrinsic value of stock option	$ 0	$ 100	$ 300
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Method Number of Simulations Used	100,000
Deferred shares granted		602,148	715,539
Average grant date fair value		$ 25.10	$ 13.64
Deferred shares vested and released		314,711	253,241
Weighted average fair value		$ 16.23	$ 19.60
Employee Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, equal annual installments	1 year
Employee Award [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Director Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period, equal annual installments	1 year
Market Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Pro-rate of original awards, minimum	0.00%
Pro-rate of original awards maximum	200.00%
Vest in 2021 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum threshold shares scheduled to vest for performance based shares	232,000
Vest in 2022 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum threshold shares scheduled to vest for performance based shares	170,000
Vest in 2023 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum threshold shares scheduled to vest for performance based shares	200,000