Document and Entity Information	12 Months Ended
	Dec. 31, 2012
Document And Entity Information [Abstract]
Document Type	20-F
Document Period End Date	Dec. 31, 2012
Amendment Flag	false
Entity Registrant Name	Seanergy Maritime Holdings Corp.
Entity Central Index Key	0001448397
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well Known Seasoned Issuer	No
Entity Common Stock Shares Outstanding	11,959,282
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY