Industry Segment Information (Schedule of Segment Reporting Information Impacts on Statement of Operations, by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Segment Reporting Information [Line Items]
Total operating revenues	$ 113,788	$ 109,182	$ 223,181	$ 221,133
Total operating income (loss)	8,642	(4,460)	20,918	(2,420)
Interest and other expense, net	(1,775)	(608)	(2,796)	(967)
Earnings (loss) before income taxes	6,867	(5,068)	18,122	(3,387)
Irrigation [Member]
Segment Reporting Information [Line Items]
Total operating revenues	92,073	95,766	174,425	183,376
Total operating income (loss)	9,614	7,521	19,371	15,304
Irrigation [Member] | North America [Member]
Segment Reporting Information [Line Items]
Total operating revenues	65,667	57,681	118,280	114,145
Irrigation [Member] | International [Member]
Segment Reporting Information [Line Items]
Total operating revenues	26,406	38,085	56,145	69,231
Infrastructure [Member]
Segment Reporting Information [Line Items]
Total operating revenues	21,715	13,416	48,756	37,757
Total operating income (loss)	6,358	(446)	15,126	3,722
Corporate Segment
Segment Reporting Information [Line Items]
Total operating income (loss)	$ (7,330)	$ (11,535)	$ (13,579)	$ (21,446)