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, 2013 Segment	May 31, 2012	May 31, 2013	May 31, 2012	Aug. 31, 2012
Segment Reporting Information [Line Items]
Number of reportable segments	3
Net sales	$ 344,205	$ 343,268	$ 952,482	$ 954,153
Operating profit (Loss)	57,042	58,850	137,387	154,809
Assets	1,919,474		1,919,474		2,007,119
Assets of Disposal Group, Including Discontinued Operation, Current	264,058		264,058		0
Industrial
Segment Reporting Information [Line Items]
Net sales	111,308	110,102	311,429	308,696
Operating profit (Loss)	32,426	30,682	85,782	85,307
Assets	284,286		284,286		268,735
Energy
Segment Reporting Information [Line Items]
Net sales	99,158	96,399	270,721	255,758
Operating profit (Loss)	19,736	18,515	44,800	43,364
Assets	552,188		552,188		540,409
Electrical
Segment Reporting Information [Line Items]
Assets	0		0		437,914
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	133,739	136,767	370,332	389,699
Operating profit (Loss)	12,754	18,467	28,654	50,747
Assets	657,951		657,951		667,550
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales	68,202	75,417	189,064	220,696
Other
Segment Reporting Information [Line Items]
Net sales	65,537	61,350	181,268	169,003
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(7,874)	(8,814)	(21,849)	(24,609)
Assets	$ 160,991		$ 160,991		$ 92,511