Quarterly report pursuant to Section 13 or 15(d)

Supplemental Disclosures (Details)

v3.19.2
Supplemental Disclosures (Details) - USD ($)
 3 Months Ended 9 Months Ended
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Sep. 30, 2018
Payments for Repurchase of Equity [Abstract]        
Repurchases of common stock $ 61,576,000 $ 45,414,000 $ 62,614,000  
Line of Credit Facility [Abstract]        
Long-term debt   268,000   $ 374,000
Loss Contingency, Information about Litigation Matters [Abstract]        
Loss contingency, maximum potential loss   31,000,000.0    
Credit Agreement Expiring 2022        
Debt Instrument, Periodic Payment [Abstract]        
Interest paid   2,300,000 $ 100,000  
Credit Agreement Expiring 2022 | Line of Credit        
Line of Credit Facility [Abstract]        
Long-term debt   0    
Mutual Fund        
Retirement Benefits [Abstract]        
Investments in mutual funds   $ 20,700,000    
Restricted Stock Units (RSUs)        
Employee Benefits and Share-based Compensation, Noncash [Abstract]        
Granted (in shares)   355,000    
Vesting period   5 years    
Restricted Stock Units (RSUs) | Member of Board of Directors        
Employee Benefits and Share-based Compensation, Noncash [Abstract]        
Vesting period   1 year    
Common Stock        
Payments for Repurchase of Equity [Abstract]        
Common shares purchased 995,000 716,000 1,012,000  
Stock Repurchase Program, June 2018 | Common Stock        
Payments for Repurchase of Equity [Abstract]        
Stock repurchase programs, authorized amount   $ 200,000,000    
Common shares purchased   700,000    
Repurchases of common stock   $ 45,400,000    
Stock Repurchase Program, August 2015 | Common Stock        
Payments for Repurchase of Equity [Abstract]        
Common shares purchased     1,000,000.0  
Repurchases of common stock     $ 62,600,000  
Stock Repurchase Authorized Program, June 2018 | Common Stock        
Payments for Repurchase of Equity [Abstract]        
Amount remaining available for future stock repurchases   $ 147,400,000