Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2012	Jan. 31, 2013	Jun. 30, 2012
Document and Entity Information [Abstract]
Entity Registrant Name	SWIFT ENERGY CO
Entity Central Index Key	0000351817
Document Type	10-K
Current Fiscal Year End Date	--12-31
Document Period End Date	Dec. 31, 2012
Amendment Flag	false
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		43,002,344
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	No
Entity Public Float			$ 778,385,135