Annual report pursuant to Section 13 and 15(d)

Changes in Projected Benefit Obligations, Fair Value of Plan Assets and Funded Status of Defined Benefit Pension Plans (Detail)

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Changes in Projected Benefit Obligations, Fair Value of Plan Assets and Funded Status of Defined Benefit Pension Plans (Detail) - USD ($)
$ in Thousands
12 Months Ended
Aug. 31, 2017
Aug. 31, 2016
Aug. 31, 2015
Reconciliation of plan assets:      
Fair value of plan assets at beginning of year $ 39,489    
Fair value of plan assets at end of year 40,027 $ 39,489  
United States Pension Plan of US Entity      
Reconciliation of benefit obligations:      
Benefit obligation at beginning of year 50,409 45,612  
Interest cost 1,690 1,970 $ 1,920
Defined Benefit Plan, Actuarial Gain (Loss) (1,997) 5,604  
Defined Benefit Plan, Benefits Paid (3,296) (2,777)  
Benefit obligation at end of year 46,806 50,409 45,612
Reconciliation of plan assets:      
Fair value of plan assets at beginning of year 39,489 39,181  
Defined Benefit Plan, Actual Return on Plan Assets 3,599 2,687  
Defined Benefit Plan, Contributions by Employer 235 398  
Benefits paid from plan assets (3,296) (2,777)  
Fair value of plan assets at end of year 40,027 39,489 $ 39,181
Funded status of the plans (underfunded) (6,779) (10,920)  
Fair Value, Inputs, Level 2 | Fixed Income Securities      
Reconciliation of plan assets:      
Fair value of plan assets at beginning of year 11,723    
Fair value of plan assets at end of year $ 11,614 $ 11,723