Document Entity Information (USD $)	12 Months Ended
	Dec. 31, 2011	Mar. 23, 2012	Jun. 30, 2011
Entity Information [Line Items]
Entity Registrant Name	SMITH MIDLAND CORP
Entity Central Index Key	0000924719
Current Fiscal Year End Date	--12-31
Entity Filer Category	Smaller Reporting Company
Document Type	10-K
Document Period End Date	Dec. 31, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		4,785,262
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 6,624,834