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, 2012	May 31, 2011	May 31, 2012	May 31, 2011	Aug. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 429,215	$ 392,777	$ 1,200,038	$ 1,041,887
Operating profit	67,664	58,001	174,401	136,619
Assets	2,034,109		2,034,109		2,056,681
Industrial
Segment Reporting Information [Line Items]
Net sales	110,102	107,759	308,696	284,086
Operating profit	30,682	29,517	85,307	69,853
Assets	277,918		277,918		263,680
Energy
Segment Reporting Information [Line Items]
Net sales	96,399	78,002	255,758	210,333
Operating profit	18,515	13,545	43,364	32,194
Assets	532,871		532,871		517,428
Electrical
Segment Reporting Information [Line Items]
Net sales	85,947	80,329	245,885	205,901
Operating profit	8,814	5,462	19,592	14,168
Assets	506,248		506,248		547,556
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	136,767	126,687	389,699	341,567
Operating profit	18,467	19,977	50,747	47,203
Assets	621,197		621,197		632,242
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales	75,417	94,423	220,696	250,926
Other
Segment Reporting Information [Line Items]
Net sales	61,350	32,264	169,003	90,641
General Corporate
Segment Reporting Information [Line Items]
Operating profit	(8,814)	(10,500)	(24,609)	(26,799)
Assets	$ 95,875		$ 95,875		$ 95,775