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Business acquisition related costs pro forma net of tax.

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Business development and acquisition integration expenses related to the merger.

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Number of joint ventures.

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Share-based compensation arrangement by share-based payment award, converted at business acquisition.

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Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity.

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Number of shares of equity interests issued or issuable to acquire entity.

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This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount of gain (loss), before tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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The cash outflow associated with the purchase of noncontrolling interest during the period.

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Price of a single share of a number of saleable stocks of a company.

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Business Combinations and Divestitures - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	12 Months Ended	0 Months Ended
	Aug. 15, 2014	Dec. 31, 2014 JointVentures	Jul. 01, 2014	Jan. 27, 2014
Acquisitions And Divestitures [Line Items]
Pretax gain on divestiture of business	$ 47,804
Payment to acquire the remaining interest in the joint ventures		19,480
Number of joint ventures		2mlm_NumberOfJointVentures
Texas Industries Inc.
Acquisitions And Divestitures [Line Items]
Number of shares issued per single share				0.7
Common shares issued to former shareholders				20,309,000
Stock price			$ 132
Aggregate value of common shares issued to former shareholders			2,680,788
Stock options and stock appreciation rights converted into stock awards			71,085
Total consideration transferred		2,756,934
Total revenues from operations included in the consolidated earnings statements		539,061
Total earnings from operations included in the consolidated earnings statements		42,239
Business development and acquisition integration expenses inclusive of severance cost		90,487
Pro forma after tax expense		$ 51,776