Business Segments - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014 Segment	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Reportable business segments	3us-gaap_NumberOfReportableSegments
Machinery and equipment acquired through capital leases	$ 7,788,000mlm_CapitalLeaseAcquired	$ 10,341,000mlm_CapitalLeaseAcquired
Acquisition of land through asset exchange	2,091,000		690,000
Corporate
Segment Reporting Information [Line Items]
Acquisition of land through asset exchange	$ 3,591,000

The amount of fixed assets that an Entity acquires in a noncash (or part noncash) acquisition. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Name:	us-gaap_NoncashOrPartNoncashAcquisitionFixedAssetsAcquired1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration