Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 22, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Aegion Corp
Document Type	10-K
Current Fiscal Year End Date	--12-31
Entity Public Float			$ 724,676,376
Entity Common Stock, Shares Outstanding (in shares)		32,635,327
Amendment Flag	false
Entity Central Index Key	0000353020
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY