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Capital Stock and Share Repurchase Capital Stock and Share Repurchase Additional Information (Details) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended
Nov. 30, 2014
Oct. 01, 2014
Aug. 31, 2014
Mar. 19, 2014
Sep. 28, 2011
Equity [Abstract]          
Stock Repurchase Program, Number of Shares Authorized to be Repurchased   7,000,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased   7,000,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased 7,000,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Stock Repurchase Program, Number of Shares Authorized to be Repurchased, Cumulative   21,000,000atu_StockRepurchaseProgramNumberofSharesAuthorizedtobeRepurchasedCumulative      
Treasury Stock, Shares 15,511,517us-gaap_TreasuryStockShares   12,195,359us-gaap_TreasuryStockShares    
Treasury Stock, Shares, Acquired 3,316,158us-gaap_TreasuryStockSharesAcquired        
Treasury Stock, Value, Acquired, Cost Method $ 104.4us-gaap_TreasuryStockValueAcquiredCostMethod        
Treasury Stock Acquired, Average Cost Per Share $ 31.46us-gaap_TreasuryStockAcquiredAverageCostPerShare