Summary of Financial Information by Reportable Segment and Product Line (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014 Segment	Feb. 28, 2013	Aug. 31, 2013
Segment Reporting Information [Line Items]
Number of reportable segments			3
Net sales	$ 327,770	$ 300,468	$ 667,326	$ 608,277
Operating profit (Loss)	38,981	36,871	82,628	80,345
Assets	1,959,134		1,959,134		2,119,332
Assets of discontinued operations	0		0		272,606
Industrial
Segment Reporting Information [Line Items]
Net sales	93,571	98,999	192,212	200,121
Operating profit (Loss)	26,477	26,350	53,374	53,356
Assets	280,498		280,498		280,110
Energy
Segment Reporting Information [Line Items]
Net sales	106,031	80,794	213,956	171,563
Operating profit (Loss)	9,504	9,677	18,427	25,064
Assets	851,618		851,618		817,547
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	128,168	120,675	261,158	236,593
Operating profit (Loss)	9,548	8,275	22,737	15,900
Assets	690,537		690,537		652,581
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales	67,278	56,468	138,927	114,498
Other
Segment Reporting Information [Line Items]
Net sales	60,890	64,207	122,231	122,095
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(6,548)	(7,431)	(11,910)	(13,975)
Assets	$ 136,481		$ 136,481		$ 96,488