Significant Accounting Policies (Basic And Diluted Earnings Per Common Share) (Details) (USD $) Share data in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Significant Accounting Policies
Net earnings from continuing operations attributable to Martin Marietta Materials, Inc.	$ 35,795,000	$ 54,412,000	$ 18,416,000	$ 30,088,000
Less: Distributed and undistributed earnings attributable to unvested awards	298,000	574,000	313,000	392,000
Basic and diluted net earnings available to common shareholders from continuing operations attributable to Martin Marietta Materials, Inc.	35,497,000	53,838,000	18,103,000	29,696,000
Basic and diluted net earnings (Loss) from discontinued operations	4,000	(13,000)	(31,000)	132,000
Basic and diluted net earnings available to common shareholders attributable to Martin Marietta Materials, Inc.	35,501,000	53,825,000	18,072,000	29,828,000
Basic weighted-average common shares outstanding	45,628	45,463	45,606	45,431
Effect of dilutive employee and director awards	166	194	168	188
Diluted weighted-average common shares outstanding	45,794	45,657	45,774	45,619
Consolidated comprehensive earnings	$ 41,101,000	$ 55,990,000	$ 22,501,000	$ 35,798,000

Accounting Policies Abstract

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Basic and diluted net income loss attributable to common shareholders of reporting entity.

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- Definition

Income loss from continuing operations net of tax attributable to common shareholders of reporting entity.

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Aggregate of earnings distributed and earnings allocated to participating securities under the two-class method to the extent that participating securities may share in earnings as if all of the earnings for the period had been distributed.

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- Definition

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph A5
-Appendix A

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 29

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph a

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- Definition

This element represents the income or loss from continuing operations attributable to the reporting entity which may also be defined as revenue less expenses and taxes from ongoing operations before extraordinary items and cumulative effects of changes in accounting principles, but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 29

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 28

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph b(1)

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This element represents the overall income (loss) from a disposal group apportioned to the parent that is classified as a component of the entity, net of income tax, reported as a separate component of income before extraordinary items and the cumulative effect of accounting changes after deduction or consideration of the amount which may be allocable to noncontrolling interests, if any. Includes the following (net of tax): income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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- Definition

Aggregate awards of share options and nonvested shares to be issued to an employee under a share-based compensation arrangement are considered options for purposes of computing diluted earnings per share. Such share-based awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their exercise may be contingent upon vesting. Those share-based awards are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive (or be able to sell) the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share-based compensation arrangements shall be computed using the treasury stock method. If the equity share options or other equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 20

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- Definition

The average number of shares issued and outstanding that are used in calculating diluted EPS, determined based on the timing of issuance of shares in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph a

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 8

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Number of [basic] shares, after adjustment for contingently issuable shares and other shares not deemed outstanding, determined by relating the portion of time within a reporting period that common shares have been outstanding to the total time in that period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph a

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 8

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