Financing Arrangements (Details) - USD ($)
1 Months Ended 6 Months Ended
Mar. 01, 2016
Mar. 04, 2014
Mar. 10, 2016
Jan. 31, 2016
Financing Arrangements        
Unamortized debt issuance costs       $ 1,129,000
Credit Agreement        
Financing Arrangements        
Maximum borrowing capacity   $ 250,000,000    
Debt issuance costs   1,318,000    
Fees on unused portion of credit facilities (as a percent)       0.25%
Shares of foreign subsidiaries pledged as security (as a percent)       65.00%
Outstanding borrowings       $ 133,500,000
Credit Agreement | Subsequent Events        
Financing Arrangements        
Outstanding borrowings     $ 139,000,000  
Repayment of borrowings     $ 8,000,000  
Credit Agreement | North American Science Associates Inc | Subsequent Events        
Financing Arrangements        
Amount borrowed $ 13,500,000      
Credit Agreement | Minimum        
Financing Arrangements        
Fees on unused portion of credit facilities (as a percent)       0.20%
Credit Agreement | Maximum        
Financing Arrangements        
Fees on unused portion of credit facilities (as a percent)       0.40%
Credit Agreement | Lender's base rate        
Financing Arrangements        
Margin on reference rate (as a percent)       0.50%
Reference rate (as a percent)       3.50%
Credit Agreement | Lender's base rate | Minimum        
Financing Arrangements        
Margin on reference rate (as a percent)       0.25%
Credit Agreement | Lender's base rate | Maximum        
Financing Arrangements        
Margin on reference rate (as a percent)       1.25%
Credit Agreement | LIBOR        
Financing Arrangements        
Margin on reference rate (as a percent)       1.50%
Credit Agreement | LIBOR | Minimum        
Financing Arrangements        
Margin on reference rate (as a percent)       1.25%
Reference rate (as a percent)       0.42%
Credit Agreement | LIBOR | Maximum        
Financing Arrangements        
Margin on reference rate (as a percent)       2.25%
Reference rate (as a percent)       0.90%
Revolving Credit Facility        
Financing Arrangements        
Maximum borrowing capacity   $ 250,000,000    
Term of line of credit facility   5 years    
Maximum additional borrowing capacity available at the entity's option   $ 100,000,000    
Unamortized debt issuance costs   512,000    
Borrowings of foreign currency        
Financing Arrangements        
Maximum borrowing capacity   100,000,000    
Letters of credit        
Financing Arrangements        
Maximum borrowing capacity   30,000,000    
Swing line loans        
Financing Arrangements        
Maximum borrowing capacity   $ 10,000,000