Quarterly report pursuant to Section 13 or 15(d)

Contingencies and Litigation - Additional Information (Detail)

v2.4.1.9
Contingencies and Litigation - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Nov. 30, 2014
Aug. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations and Divestiture Activities[Line Items]    
Outstanding letters of credit $ 15.0us-gaap_LettersOfCreditOutstandingAmount $ 14.0us-gaap_LettersOfCreditOutstandingAmount
Litigation Settlement, Expense 2.0us-gaap_LitigationSettlementExpense  
Discounted present value of future minimum lease payments 19.6atu_DiscountedPresentValueOfFutureMinimumLeasePayments  
Electrical    
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations and Divestiture Activities[Line Items]    
Discounted present value of future minimum lease payments $ 13.4atu_DiscountedPresentValueOfFutureMinimumLeasePayments
/ us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis
= atu_ElectricalMember