Acquisitions (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Aug. 22, 2014	Aug. 22, 2014	Dec. 21, 2013	Jun. 30, 2014
Business Acquisition [Line Items]
Goodwill	$ 72,212,000		$ 72,212,000					$ 69,837,000
Revenues	342,880,000	310,998,000	664,563,000	537,215,000
Operating income	(3,671,000)	14,817,000	4,876,000	25,579,000
HDB, Inc. [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition						Aug. 22, 2014
Business Acquisition, Name of Acquired Entity					HDB Ltd. Limited Partnership ("HDB").
Business Combination, Consideration Transferred					5,551,000
Tax deductible goodwill					3,054,000	3,054,000
Kvaerner NAC
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition							Dec. 21, 2013
Business Acquisition, Percentage of Voting Interests Acquired							100.00%
Business Acquisition, Name of Acquired Entity							Kvaerner North American Construction Ltd. and substantially all of the assets of Kvaerner North American Construction Inc
Business Combination, Consideration Transferred							88,300,000
Goodwill							39,295,000
Tax deductible goodwill							28,500,000
Noncontrolling Interest, Description			The Joint Venture was formed by Kvaerner North American Construction Inc. and an engineering firm to engineer and construct a combined cycle power plant in Dover, Delaware.
Noncontrolling Interest, Ownership Percentage by Parent	65.00%		65.00%
mtrx_JointVentureValue							2,000,000
mtrx_ControllingInterestOfJointVenture,Value	14,100,000		14,100,000				1,300,000
Noncontrolling interest of consolidated joint venture	7,600,000		7,600,000				700,000
SM Electric Trade Name [Member]
Business Acquisition [Line Items]
Finite-Lived Trade Names, Gross	$ 1,400,000		$ 1,400,000