Summary of Financial Information by Reportable Segment and Product Line (Details) $ in Thousands	3 Months Ended
	Nov. 30, 2015 USD ($) Segment	Nov. 30, 2014 USD ($)	Aug. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	3
Net sales	$ 305,011	$ 327,765
Operating profit (Loss)	25,371	38,218
Assets	1,623,535		$ 1,636,917
Industrial
Segment Reporting Information [Line Items]
Net sales	88,870	102,413
Operating profit (Loss)	20,554	26,705
Assets	288,032		293,738
Energy
Segment Reporting Information [Line Items]
Net sales	113,764	111,522
Operating profit (Loss)	10,094	12,442
Assets	609,928		601,521
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	102,377	113,830
Operating profit (Loss)	3,522	6,278
Assets	580,295		588,200
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales	54,075	58,468
Other
Segment Reporting Information [Line Items]
Net sales	48,302	55,362
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(8,799)	$ (7,207)
Assets	$ 145,280		$ 153,458