Quarterly report pursuant to Section 13 or 15(d)

Supplemental disclosures (Details)

v3.8.0.1
Supplemental disclosures (Details) - USD ($)
shares in Thousands
 3 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Aug. 31, 2015
Payments for Repurchase of Equity [Abstract]      
Repurchases of common stock $ 1,038,000 $ 28,767,000  
Selling, general and administrative expense:      
Change in selling, general and administrative expenses $ 69,559,000 $ 65,398,000  
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 17 559  
United Kingdom      
Restructuring Charges [Abstract]      
Restructuring charges   $ 2,200,000  
Mutual Fund      
Retirement Benefits [Abstract]      
Investments in mutual funds $ 16,200,000    
Estimated Revision Had Accounting Principle Been Adopted Previous Fiscal Year [Member]      
Selling, general and administrative expense:      
Change in selling, general and administrative expenses (1,200,000)    
Stock Repurchase Program, August 2015      
Payments for Repurchase of Equity [Abstract]      
Stock repurchase programs, authorized amount     $ 200,000,000
Amount remaining available for future stock repurchases $ 108,800,000    
Stock Repurchase Program, August 2015 | Common Stock      
Payments for Repurchase of Equity [Abstract]      
Common shares repurchased 17 600  
Repurchases of common stock $ 1,000,000 $ 28,800,000