Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 29, 2016
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, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	FY
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		44,747,966
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float	$ 87,818,801