Note 2 - Accounting Policies - Investments in Variable Interest Entities (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Current assets		$ 454,400		$ 450,215
Current liabilities		212,451		234,041
Revenue	[1]	287,375	$ 276,904
Gross profit	[1]	49,884	48,295
Net income attributable to Aegion Corporation		(1,632)	(4,001)
Variable Interest Entity, Primary Beneficiary [Member]
Current assets		16,424		18,304
Non-current assets		7,956		7,635
Current liabilities		6,230		8,261
Non-current liabilities		2,744		$ 1,962
Revenue		7,729	5,925
Gross profit		2,303	1,635
Net income attributable to Aegion Corporation		$ 285	$ 33

[1] Revenues and gross profit are attributed to the country of origin