Quarterly report pursuant to Section 13 or 15(d)

Supplemental Disclosures - Narrative (Details)

v3.20.1
Supplemental Disclosures - Narrative (Details) - USD ($)
shares in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2020
Mar. 31, 2019
Payments for Repurchase of Equity [Abstract]        
Repurchases of common stock $ 165,061,000 $ 4,084,000 $ 166,959,000 $ 45,414,000
Investments in mutual funds $ 18,400,000   18,400,000  
Interest paid     500,000 1,800,000
Income taxes paid     $ 52,900,000 $ 37,200,000
Restricted Stock Units (RSUs)        
Payments for Repurchase of Equity [Abstract]        
Granted (in shares)     316  
Vesting period     5 years  
Restricted Stock Units (RSUs) | Member of Board of Directors        
Payments for Repurchase of Equity [Abstract]        
Vesting period     1 year  
Common Stock        
Payments for Repurchase of Equity [Abstract]        
Common shares repurchased (in shares) 2,741 62 2,767 716
Repurchases of common stock     $ 167,000,000.0 $ 45,400,000
Stock Repurchase Program, March 2020 | Common Stock        
Payments for Repurchase of Equity [Abstract]        
Stock repurchase programs, authorized amount $ 200,000,000   200,000,000  
Amount remaining available for future stock repurchases $ 150,000,000.0   $ 150,000,000.0