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. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018
Segment Reporting Information [Line Items]
Total operating revenues	$ 109,182	$ 130,339	$ 221,133	$ 254,865
Total operating income (loss)	(4,460)	7,291	(2,420)	13,492
Interest and other expense, net	(608)	(1,615)	(967)	(3,024)
Earnings (loss) before income taxes	(5,068)	5,676	(3,387)	10,468
Capital expenditures	6,000	2,724	11,701	4,715
Depreciation and amortization	3,465	4,264	6,889	8,599
Irrigation [Member]
Segment Reporting Information [Line Items]
Total operating revenues	95,766	111,865	183,376	215,218
Total operating income (loss)	7,521	11,933	15,304	19,784
Capital expenditures	2,341	2,362	4,478	4,035
Depreciation and amortization	2,366	2,994	4,698	6,073
Irrigation [Member] | North America [Member]
Segment Reporting Information [Line Items]
Total operating revenues	57,681	78,863	114,145	146,616
Irrigation [Member] | International [Member]
Segment Reporting Information [Line Items]
Total operating revenues	38,085	33,002	69,231	68,602
Infrastructure [Member]
Segment Reporting Information [Line Items]
Total operating revenues	13,416	18,474	37,757	39,647
Total operating income (loss)	(446)	2,519	3,722	5,810
Capital expenditures	176	268	366	464
Depreciation and amortization	919	1,144	1,884	2,282
Corporate Segment
Segment Reporting Information [Line Items]
Total operating income (loss)	(11,535)	(7,161)	(21,446)	(12,102)
Capital expenditures	3,483	94	6,857	216
Depreciation and amortization	$ 180	$ 126	$ 307	$ 244