Quarterly report pursuant to Section 13 or 15(d)

Supplemental disclosures (Details)

v3.10.0.1
Supplemental disclosures (Details) - USD ($)
shares in Thousands
 3 Months Ended 9 Months Ended
Jul. 31, 2017
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Payments for Repurchase of Equity [Abstract]          
Repurchases of common stock       $ 62,614,000 $ 28,858,000
Retirement Benefits [Abstract]          
Payment for contingent consideration liability, financing activities $ 1,700,000        
Selling, general and administrative expense:          
Change in selling, general and administrative expenses   $ 69,588,000 $ 68,308,000 211,706,000 $ 202,302,000
Loss Contingency, Information about Litigation Matters [Abstract]          
Loss contingency, maximum potential loss   31,000,000   $ 31,000,000  
Restricted Stock Units (RSUs)          
Employee Benefits and Share-based Compensation, Noncash [Abstract]          
Granted (in shares)       300  
Vesting period       5 years  
Common Stock          
Payments for Repurchase of Equity [Abstract]          
Common shares repurchased       1,012 558
United Kingdom          
Restructuring Charges [Abstract]          
Restructuring charges       $ 2,300,000 $ 2,200,000
Mutual Fund          
Retirement Benefits [Abstract]          
Investments in mutual funds   19,600,000   19,600,000  
Stock Repurchase Program, June 2018          
Payments for Repurchase of Equity [Abstract]          
Stock repurchase programs, authorized amount   200,000,000   $ 200,000,000  
Stock Repurchase Program, June 2018 | Common Stock          
Payments for Repurchase of Equity [Abstract]          
Common shares repurchased       1,000  
Repurchases of common stock       $ 62,600,000  
Stock Repurchase Program, August 2015 | Common Stock          
Payments for Repurchase of Equity [Abstract]          
Common shares repurchased         600
Repurchases of common stock         $ 28,900,000
Stock Repurchase Authorized Program, June 2018          
Payments for Repurchase of Equity [Abstract]          
Amount remaining available for future stock repurchases   $ 197,800,000   197,800,000  
Board of Directors | Restricted Stock Units (RSUs)          
Employee Benefits and Share-based Compensation, Noncash [Abstract]          
Granted (in shares)   22      
Vesting period   1 year      
Estimated Revision Had Accounting Principle Been Adopted Previous Fiscal Year          
Selling, general and administrative expense:          
Change in selling, general and administrative expenses   $ (1,000,000)   $ (3,500,000)