Summary of Financial Information by Reportable Segment and Product Line (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2014 Segment	May 31, 2013	Aug. 31, 2013
Segment Reporting Information [Line Items]
Number of reportable segments			3
Net sales	$ 378,187	$ 344,205	$ 1,045,513	$ 952,482
Operating profit (Loss)	58,780	57,042	141,408	137,387
Assets	1,947,705		1,947,705		2,119,332
Assets of discontinued operations	0		0		272,606
Industrial
Segment Reporting Information [Line Items]
Net sales	109,809	111,308	302,022	311,429
Operating profit (Loss)	34,123	32,426	87,496	85,782
Assets	322,609		322,609		280,110
Energy
Segment Reporting Information [Line Items]
Net sales	125,231	99,158	339,187	270,721
Operating profit (Loss)	19,936	19,736	38,363	44,800
Assets	805,056		805,056		817,547
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	143,147	133,739	404,304	370,332
Operating profit (Loss)	13,560	12,754	36,297	28,654
Assets	688,474		688,474		652,581
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales	75,442	68,202	214,369	189,064
Other
Segment Reporting Information [Line Items]
Net sales	67,705	65,537	189,935	181,268
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(8,839)	(7,874)	(20,748)	(21,849)
Assets	$ 131,566		$ 131,566		$ 96,488