Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Additional Information (Detail)

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Employee Benefit Plans - Additional Information (Detail) (USD $)
 12 Months Ended
Aug. 31, 2012
Aug. 31, 2011
Aug. 31, 2010
Aug. 31, 2009
Defined Benefit Plan Disclosure [Line Items]        
Pension plan actuarial gain losses, not yet recognized in net periodic benefit cost $ (15,600,000) $ (12,000,000)    
Pension plan actuarial gain losses, expected to be recognized in net periodic benefit cost in 2013 (600,000)      
Asset allocation in equity securities minimum 60.00%      
Asset allocation in equity securities maximum 80.00%      
Expected long term rate of return for assets 7.75%      
Net periodic benefit costs (credit) 366,000 556,000 48,000  
Weighted average discount rate for determining benefit obligation 3.90% 5.00% 4.60%  
Deferred compensation liability 2,689,000 2,137,000    
Expense on participant deferrals in fixed income investment option 1,500,000 1,200,000 1,000,000  
Cost of stock held in trust 1,500,000 1,000,000    
U.S. defined benefit pension plans
        
Defined Benefit Plan Disclosure [Line Items]        
Amount of benefits expected to be paid, fiscal 2013 2,600,000      
Amount of benefits expected to be paid, fiscal 2014 2,600,000      
Amount of benefits expected to be paid, fiscal 2015 2,600,000      
Amount of benefits expected to be paid, fiscal 2016 2,600,000      
Amount of benefits expected to be paid, fiscal 2017 2,600,000      
Amount of benefits expected to be paid, fiscal 2018 through 2022 14,600,000      
Define benefit plan Company contributions, year 2013 200,000      
Benefit obligation 50,870,000 44,430,000 46,967,000  
Non-US Pension Plans, Defined Benefit
        
Defined Benefit Plan Disclosure [Line Items]        
Expected long term rate of return for assets 4.80%      
Define benefit plan Company contributions, year 2013 500,000      
Net periodic benefit costs (credit) 300,000 400,000 300,000  
Weighted average discount rate for determining benefit obligation 4.00% 5.50%    
Benefit obligation 10,711,000 9,035,000    
Other post-retirement health benefits ("OPEB")
        
Defined Benefit Plan Disclosure [Line Items]        
Define benefit plan Company contributions, year 2013 300,000      
Net periodic benefit costs (credit)   200,000 200,000 200,000
Benefit obligation 3,400,000 3,300,000    
Health care cost trend rate 8.00%      
Health care cost trending downward rate by 2018 5.00%      
Eligible annual cash compensation
        
Defined Benefit Plan Disclosure [Line Items]        
Maximum employee contribution to defined contribution benefit plans 50.00%      
Maximum Company contribution to defined contribution benefit plans 3.00%      
Eligible compensation
        
Defined Benefit Plan Disclosure [Line Items]        
Employer matching contribution to employee contribution percentage 25.00%      
Eligible compensation | Maximum
        
Defined Benefit Plan Disclosure [Line Items]        
Employee contribution percentage of eligible compensation 6.00%      
Defined Contribution 401 K Plan
        
Defined Benefit Plan Disclosure [Line Items]        
Expense recognized related to defined contribution plan 6,000,000 5,600,000 2,700,000  
Supplemental Executive Retirement Plan
        
Defined Benefit Plan Disclosure [Line Items]        
Expense recognized related to defined contribution plan 700,000 600,000    
Supplemental Executive Retirement Plan | Maximum
        
Defined Benefit Plan Disclosure [Line Items]        
Employer contribution to defined contribution benefit plans   6.00%    
Supplemental Executive Retirement Plan | Minimum
        
Defined Benefit Plan Disclosure [Line Items]        
Employer contribution to defined contribution benefit plans   3.00%    
Defined Contribution Plan
        
Defined Benefit Plan Disclosure [Line Items]        
Deferred compensation liability 19,600,000 15,600,000    
Long Term Incentive Plan
        
Defined Benefit Plan Disclosure [Line Items]        
Long-term incentive plan adoption date Jul. 31, 2006      
Targeted common stock per share price appreciation to receive a lump sum cash incentive payment $ 50      
Long term incentive plan expense (income) 100,000 100,000 400,000  
Long term incentive plan liability 1,100,000 1,000,000    
Long Term Incentive Plan | Maximum
        
Defined Benefit Plan Disclosure [Line Items]        
Payment for long term incentive plan 13,300,000      
Long Term Incentive Plan | Minimum
        
Defined Benefit Plan Disclosure [Line Items]        
Payment for long term incentive plan $ 0