Quarterly report pursuant to Section 13 or 15(d)

Supplemental disclosures (Details)

v3.6.0.2
Supplemental disclosures (Details) - USD ($)
 3 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Sep. 30, 2016
Sep. 30, 2015
Aug. 31, 2015
Income Taxes Paid, Net [Abstract]          
Income taxes paid $ 3,700,000 $ 19,200,000      
Cash and Cash Equivalents [Abstract]          
Cash and cash equivalents 69,767,000 50,958,000 $ 66,199,000 $ 74,672,000  
Foreign currency translation adjustments (9,694,000) (2,159,000)      
Payments for Repurchase of Equity [Abstract]          
Stock repurchase programs, authorized amount         $ 200,000,000
Repurchases of common stock (28,767,000) $ (29,139,000)      
Amount remaining available for future stock repurchases 109,000,000        
Restructuring Charges [Abstract]          
Restructuring reserve $ 200,000        
Restricted Stock Units (RSUs)          
Employee Benefits and Share-based Compensation [Abstract]          
Granted (in shares) 400,000        
Vesting period 5 years        
Common Stock          
Payments for Repurchase of Equity [Abstract]          
Common shares repurchased 559,000 543,000      
Repurchases of common stock $ (28,800,000) $ (29,100,000)      
Non-U.S.          
Cash and Cash Equivalents [Abstract]          
Cash and cash equivalents 66,600,000        
United Kingdom          
Restructuring Charges [Abstract]          
Restructuring charges (2,200,000)        
Mutual Fund          
Compensation and Retirement Disclosure [Abstract]          
Investments in mutual funds 12,100,000        
Employee Severance | United Kingdom          
Restructuring Charges [Abstract]          
Restructuring charges (2,000,000)        
Facility Closing | United Kingdom          
Restructuring Charges [Abstract]          
Restructuring charges $ (200,000)