Revenue Recognition (Schedule of Disaggregation of Revenue by Segment) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Nov. 30, 2018	Aug. 31, 2020	Aug. 31, 2019	Aug. 31, 2018
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									$ 463,207	$ 436,320
Lease revenue									11,485	7,752
Operating revenues	$ 128,405	$ 123,106	$ 113,788	$ 109,393	$ 101,885	$ 121,054	$ 109,182	$ 111,951	474,692	444,072	$ 547,705
Irrigation [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									343,529	351,498
Lease revenue									0	0
Operating revenues									343,529	351,498	439,858
Infrastructure [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									119,678	84,822
Lease revenue									11,485	7,752
Operating revenues									131,163	92,574	$ 107,847
Point in Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									409,380	397,312
Point in Time [Member] | Irrigation [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									298,509	318,544
Point in Time [Member] | Infrastructure [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									110,871	78,768
Over Time [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									53,827	39,008
Over Time [Member] | Irrigation [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									45,020	32,954
Over Time [Member] | Infrastructure [Member]
Disaggregation Of Revenue [Line Items]
Revenue from the contracts with customers									$ 8,807	$ 6,054