Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 333,998	$ 339,679	$ 335,030	$ 324,861	$ 337,499	$ 341,872	$ 354,473	$ 325,175	$ 1,333,568	$ 1,359,019	$ 1,221,920
Gross profit	61,696	72,673	71,053	61,504	64,190	73,442	79,768	67,412	266,926	284,812	253,927
Operating income (loss)	(1,002)	13,009	14,459	3,181	(3,956)	(75,271)	21,495	14,212	29,647	(43,520)	50,791
Net income (loss)	$ (2,776)	$ 141	$ 7,198	$ (1,476)	$ (12,384)	$ (74,044)	$ 12,014	$ 7,832	$ 2,928	$ (69,401)	$ 29,453
Earnings (loss) per share attributable to Aegion Corporation:
Basic (in USD per share)	$ (0.08)	$ (0.01)	$ 0.24	$ (0.06)	$ (0.39)	$ (2.23)	$ 0.33	$ 0.18	$ 0.09	$ (2.09)	$ 0.85
Diluted (in USD per share)	$ (0.08)	$ (0.01)	$ 0.24	$ (0.06)	$ (0.39)	$ (2.23)	$ 0.32	$ 0.17	$ 0.09	$ (2.09)	$ 0.84
Restructuring charges, pre tax	$ 13,900	$ 7,400	$ 2,900	$ 5,200	$ 17,100	$ 6,700	$ 300	$ (100)
Goodwill impairment									$ 1,389	$ 45,390	$ 0
Infrastructure Solutions
Segment Reporting Information [Line Items]
Revenues									604,121	612,154	571,551
Gross profit									132,411	140,823	142,444
Operating income (loss)									23,683	(62,244)	$ 53,899
Earnings (loss) per share attributable to Aegion Corporation:
Goodwill impairment						45,400			$ 1,389	45,390
Impairment of intangible assets						$ 41,000				$ 41,000