Summary of Financial Information by Reportable Segment and Product Line (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2012	Aug. 31, 2012	May 31, 2012	Feb. 29, 2012	Nov. 30, 2011	Aug. 31, 2013	Aug. 31, 2012	Aug. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 327,260	$ 344,205	$ 300,468	$ 307,809	$ 322,368	$ 343,268	$ 300,919	$ 309,966	$ 1,279,742	$ 1,276,521	$ 1,159,310
Operating profit (loss)									190,145	204,514	172,887
Depreciation and amortization									53,902	54,263	52,996
Discontinued Operations									7,804	10,667	9,694
Capital Expenditure									23,668	22,740	23,096
Assets	2,119,332				2,007,119				2,119,332	2,007,119
Industrial
Segment Reporting Information [Line Items]
Net sales									422,620	419,295	393,013
Operating profit (loss)									117,644	114,777	98,415
Depreciation and amortization									8,553	8,358	8,655
Capital Expenditure									3,524	5,333	3,590
Assets	280,110				268,735				280,110	268,735
Energy
Segment Reporting Information [Line Items]
Net sales									363,372	349,163	293,060
Operating profit (loss)									63,280	62,205	49,345
Depreciation and amortization									18,451	18,115	18,152
Capital Expenditure									9,417	8,962	8,978
Assets	817,547				540,409				817,547	540,409
Electrical
Segment Reporting Information [Line Items]
Assets	0				437,914				0	437,914
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales									493,750	508,063	473,237
Operating profit (loss)									40,328	60,851	63,612
Depreciation and amortization									16,949	15,093	13,916
Capital Expenditure									7,001	3,463	5,966
Assets	652,581				667,550				652,581	667,550
General Corporate
Segment Reporting Information [Line Items]
Operating profit (loss)									(31,107)	(33,319)	(38,485)
Depreciation and amortization									2,145	2,030	2,579
Capital Expenditure									867	1,905	1,902
Assets	96,488				92,511				96,488	92,511
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales									253,073	279,549	328,763
Other
Segment Reporting Information [Line Items]
Net sales									240,677	228,514	144,474
Discontinued Operations
Segment Reporting Information [Line Items]
Capital Expenditure									$ 2,859	$ 3,077	$ 2,660