Industry Segment Information (Schedule of Segment Reporting Information Impacts on Statement of Operations, by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2020	May 31, 2019
Segment Reporting Information [Line Items]
Total operating revenues	$ 123,106	$ 121,054	$ 346,287	$ 342,187
Total operating income	15,828	4,475	36,746	2,055
Interest and other expense, net	(3,563)	(1,246)	(6,359)	(2,213)
Earnings (loss) before income taxes	12,265	3,229	30,387	(158)
Irrigation [Member]
Segment Reporting Information [Line Items]
Total operating revenues	93,523	98,618	267,948	281,994
Total operating income	15,014	11,037	34,385	26,341
Irrigation [Member] | North America [Member]
Segment Reporting Information [Line Items]
Total operating revenues	60,917	62,974	179,197	177,118
Irrigation [Member] | International [Member]
Segment Reporting Information [Line Items]
Total operating revenues	32,606	35,644	88,751	104,876
Infrastructure [Member]
Segment Reporting Information [Line Items]
Total operating revenues	29,583	22,436	78,339	60,193
Total operating income	8,560	3,537	23,686	7,259
Corporate Segment
Segment Reporting Information [Line Items]
Total operating income	$ (7,746)	$ (10,099)	$ (21,325)	$ (31,545)