Debt - Additional Information (Detail) $ in Thousands	6 Months Ended
	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)
Acquired Indefinite-lived Intangible Assets [Line Items]
Credit Agreement Term	5 years
Senior secured revolving credit facility	$ 200,000	$ 200,000
mtrx_LineOfCreditFacilityExpirationDate	Mar. 13, 2019
Senior Leverage Ratio, Maximum	2.50
Senior Leverage Ratio, Minimum	1.00
Fixed Charge Coverage Ratio, Maximum	1.25
Fixed Charge Coverage Ratio, Minimum	1.00
Limit on asset dispositions	$ 20,000
Additional Margin on alternate base rate loans, Minimum	0.25%
Additional Margin on alternate base rate loans, Maximum	1.00%
Additional Margin on LIBOR loans, Minimum	1.25%
Additional Margin on LIBOR loans, Maximum	2.00%
Sublimit on Canadian dollar borrowings	$ 40,000
Additional Margin on CDOR loans, Minimum	1.25%
Additional Margin on CDOR loans, Maximum	2.00%
Additional Margin on Canadian prime rate loans, Minimum	1.75%
Additional Margin on Canadian prime rate loans, Maximum	2.50%
CDOR Rate description	sum of the annual rate of interest, which is the rate determined as being the arithmetic average of the quotations of all institutions listed in respect of the relevant CDOR interest period for Canadian Dollar denominated bankers’ acceptances, plus 0.1%
Canadian prime rate description	greater of (i) the rate of interest per annum most recently announced or established by JPMorgan Chase Bank, N.A., Toronto Branch as its reference rate in effect on such day for determining interest rates for Canadian Dollar denominated commercial loans in Canada and (ii) the CDOR Rate plus 1.0%.
Maximum limit of consolidated funded indebtedness	2.5
Consolidated EBITDA as defined in the Credit Agreement	$ 65,400
Consolidated funded indebtedness	$ 22,300
Minimum [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
Unused Credit Facility Fee	0.20%
Maximum [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
Unused Credit Facility Fee	0.35%
CDOR Rate [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
Basis spread on variable rate basis	0.10%
Canadian Prime Rate [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
Variable rate basis	CDOR
Basis spread on variable rate basis	1.00%