Summary of Financial Information by Reportable Segment and Product Line (Details) $ in Thousands	3 Months Ended		9 Months Ended
	May. 31, 2015 USD ($)	May. 31, 2014 USD ($)	May. 31, 2015 USD ($) Segment	May. 31, 2014 USD ($)	Aug. 31, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment			3
Net sales	$ 320,100	$ 378,187	$ 948,870	$ 1,045,513
Operating profit (Loss)	43,002	58,780	24,773	141,408
Assets	1,661,018		1,661,018		$ 1,856,879
Industrial
Segment Reporting Information [Line Items]
Net sales	103,546	109,809	302,448	302,022
Operating profit (Loss)	29,165	34,123	79,386	87,496
Assets	289,849		289,849		307,058
Energy
Segment Reporting Information [Line Items]
Net sales	99,297	125,231	311,029	339,187
Operating profit (Loss)	12,774	19,936	(50,457)	38,363
Assets	619,514		619,514		788,915
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	117,257	143,147	335,393	404,304
Operating profit (Loss)	8,313	13,560	16,601	36,297
Assets	624,289		624,289		643,323
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales	59,673	75,442	170,122	214,369
Other
Segment Reporting Information [Line Items]
Net sales	57,584	67,705	165,271	189,935
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(7,250)	$ (8,839)	(20,757)	$ (20,748)
Assets	$ 127,366		$ 127,366		$ 117,583