Note 1 - General (Details Textual) - USD ($) $ in Millions		3 Months Ended
May 04, 2018	Sep. 30, 2018	Jun. 30, 2018
OMAN \| Company Joint Venture [Member]
Business Acquisition, Percentage of Voting Interests Acquired	50.00%
OMAN \| Aegion International [Member]
Business Acquisition, Percentage of Voting Interests Acquired	51.00%
Hebna [Member]
Business Combination, Consideration Transferred, Total	$ 6	$ 3	$ 3

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6613-128477

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=116859721&loc=d3e6578-128477

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Balance Type:	credit
Period Type:	duration