General - Additional Information (Details) $ in Thousands, € in Millions, £ in Millions, NZD in Millions										3 Months Ended
	Mar. 01, 2017 GBP (£)	Mar. 01, 2017 USD ($)	Jul. 01, 2016 NZD company	Jul. 01, 2016 USD ($) company	Jun. 02, 2016 EUR (€)	Jun. 02, 2016 USD ($)	May 13, 2016 USD ($) country	Feb. 18, 2016 USD ($)	Feb. 01, 2016 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2017 NZD	Sep. 30, 2017 USD ($)	Mar. 01, 2017 USD ($)	Jul. 01, 2016 USD ($)
Environmental Techniques
General [Line Items]
Total consideration recorded	£ 6.5	$ 8,046
Amount held in escrow	£ 1.0													$ 1,200
CSL and BCS
General [Line Items]
Total consideration recorded			NZD 8.9	$ 6,400
Number of companies acquired | company			2	2
Cash payments to acquire business			NZD 7.5	$ 5,500
Milestone payments			2.0	1,400
Working capital adjustment			0.2	$ 100
Estimated earnout consideration			NZD 1.2									NZD 1.0	$ 800		$ 900
Earnout consideration reversed										$ 100
LMJ
General [Line Items]
Total consideration recorded					€ 2.9	$ 3,200
Fyfe Europe
General [Line Items]
Total consideration recorded							$ 3,000
Cash payments to acquire business							$ 2,800
Number of countries in which entity operates | country							72
Contingent consideration paid											$ 200
Underground Solutions
General [Line Items]
Total consideration recorded								$ 88,400
Cash payments to acquire business								85,000
Discounted value of net operating loss tax assets								5,000
Working capital adjustment								$ 1,600
Bayou Perma-Pipe Canada, Ltd
General [Line Items]
Ownership percentage by parent									51.00%
Consideration received									$ 9,600
Proceeds from divestiture									7,600
Disposal, note receivable									$ 2,000
Aegion South Africa Proprietary Limited [Member]
General [Line Items]
Ownership percentage by parent												60.00%	60.00%
Ownership percentage by noncontrolling owners												40.00%	40.00%