Industry Segment Information (Schedule of Segment Reporting Information Impacts on Balance Sheet, by Segment) (Details) - USD ($) $ in Thousands	May 31, 2019	Aug. 31, 2018	May 31, 2018
Segment Reporting Information [Line Items]
Total assets	$ 505,922	$ 499,815	$ 519,778
Irrigation [Member]
Segment Reporting Information [Line Items]
Total assets	306,714	277,712	326,058
Infrastructure [Member]
Segment Reporting Information [Line Items]
Total assets	80,971	69,919	88,616
Corporate Segment
Segment Reporting Information [Line Items]
Total assets	$ 118,237	$ 152,184	$ 105,104