Quarterly report pursuant to Section 13 or 15(d)

Capital Stock and Share Repurchase Share Repurchase (Details)

v2.4.1.9
Capital Stock and Share Repurchase Share Repurchase (Details) (USD $)
 6 Months Ended 12 Months Ended 30 Months Ended 42 Months Ended
Feb. 28, 2015
Aug. 31, 2014
Aug. 31, 2013
Aug. 31, 2012
Feb. 28, 2015
Feb. 28, 2015
Mar. 16, 2015
Equity, Class of Treasury Stock [Line Items]              
Treasury Stock, Shares, Acquired 6,241,158us-gaap_TreasuryStockSharesAcquired 8,211,846us-gaap_TreasuryStockSharesAcquired 1,324,762us-gaap_TreasuryStockSharesAcquired 2,658,751us-gaap_TreasuryStockSharesAcquired 18,436,517us-gaap_TreasuryStockSharesAcquired    
Treasury Stock Acquired, Average Cost Per Share $ 28.90us-gaap_TreasuryStockAcquiredAverageCostPerShare $ 34.52us-gaap_TreasuryStockAcquiredAverageCostPerShare $ 31.55us-gaap_TreasuryStockAcquiredAverageCostPerShare $ 23.70us-gaap_TreasuryStockAcquiredAverageCostPerShare   $ 30.84us-gaap_TreasuryStockAcquiredAverageCostPerShare  
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased 2,563,483us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased       2,563,483us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased 2,563,483us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased  
Subsequent Event [Member]              
Equity, Class of Treasury Stock [Line Items]              
Stock Repurchase Program, Number of Shares Authorized to be Repurchased             7,000,000us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember