General - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenues	$ 354,473	$ 302,396	$ 680,530	$ 605,266
Net income (loss) attributable to Aegion Corporation	$ 11,100	$ 3,477	$ 16,798	$ 147
Diluted earnings (loss) per share (in dollars per share)	$ 0.33	$ 0.10	$ 0.49	$ 0.00

The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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