Document And Entity Information	6 Months Ended
	Jun. 30, 2011	Jul. 22, 2011
Document And Entity Information
Document Type	10-Q
Document Period End Date	Jun. 30, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Registrant Name	MARTIN MARIETTA MATERIALS INC
Entity Central Index Key	0000916076
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		45,683,317