Industry Segment Information (Schedule of Segment Reporting Information Impacts on Balance Sheet, by Segment) (Details) - USD ($) $ in Thousands	Feb. 28, 2019	Aug. 31, 2018	Feb. 28, 2018
Segment Reporting Information [Line Items]
Total assets	$ 500,105	$ 500,256	$ 522,354
Irrigation [Member]
Segment Reporting Information [Line Items]
Total assets	309,532	277,712	348,298
Infrastructure [Member]
Segment Reporting Information [Line Items]
Total assets	69,829	69,919	79,342
Corporate Segment
Segment Reporting Information [Line Items]
Total assets	$ 120,744	$ 152,625	$ 94,714