Summary of Financial Information by Reportable Segment and Product Line (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Nov. 30, 2014 Segment	Nov. 30, 2013	Aug. 31, 2014
Segment Reporting Information [Line Items]
Number of reportable segments	3us-gaap_NumberOfReportableSegments
Net sales	$ 327,765us-gaap_SalesRevenueNet	$ 339,556us-gaap_SalesRevenueNet
Operating profit (Loss)	38,218us-gaap_OperatingIncomeLoss	43,647us-gaap_OperatingIncomeLoss
Assets	1,787,464us-gaap_Assets		1,856,879us-gaap_Assets
Industrial
Segment Reporting Information [Line Items]
Net sales	102,413	98,641
Operating profit (Loss)	26,705	26,897
Assets	293,531		307,058
Energy
Segment Reporting Information [Line Items]
Net sales	111,522	107,925
Operating profit (Loss)	12,442	8,923
Assets	746,982		788,915
Engineered Solutions
Segment Reporting Information [Line Items]
Net sales	113,830	132,990
Operating profit (Loss)	6,278	13,190
Assets	643,239		643,323
Vehicle Systems
Segment Reporting Information [Line Items]
Net sales	58,468	71,649
Other
Segment Reporting Information [Line Items]
Net sales	55,362	61,341
General Corporate
Segment Reporting Information [Line Items]
Operating profit (Loss)	(7,207)	(5,363)
Assets	$ 103,712		$ 117,583

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.18)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 7

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 18

-Article 5

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

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