Revenue Recognition (Schedule of Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	$ 107,975		$ 218,322
Lease revenue	1,207		2,811
Operating revenues	109,182	$ 130,339	221,133	$ 254,865
Irrigation [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	95,766		183,376
Lease revenue	0		0
Operating revenues	95,766	111,865	183,376	215,218
Infrastructure [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	12,209		34,946
Lease revenue	1,207		2,811
Operating revenues	13,416	$ 18,474	37,757	$ 39,647
Point in Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	96,856		199,189
Point in Time [Member] | Irrigation [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	85,939		167,025
Point in Time [Member] | Infrastructure [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	10,917		32,164
Over Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	11,119		19,133
Over Time [Member] | Irrigation [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	9,827		16,351
Over Time [Member] | Infrastructure [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers	$ 1,292		$ 2,782