Annual report pursuant to Section 13 and 15(d)

Equity - Narrative (Details)

v3.20.2
Equity - Narrative (Details) - USD ($)
$ / shares in Units, shares in Millions
2 Months Ended 12 Months Ended
Nov. 19, 2020
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2018
Mar. 31, 2020
Stock-based compensation          
Shares available for grants (in shares)   0.5      
Total income tax benefit recognized   $ 8,000,000.0 $ 9,900,000 $ 8,700,000  
Liability related to forfeitures for tax payments   $ 9,818,000 $ 10,614,000 $ 8,733,000  
Stock repurchase programs, authorized amount         $ 200,000,000
Common shares repurchased (in shares)   2.8 0.7 1.1  
Common shares repurchased, cost   $ 166,959,000 $ 46,797,000 $ 67,572,000  
Amount remaining available for future stock repurchases   $ 150,000,000.0      
RSUs awarded in 2009 and after | Share-based Payment Arrangement, Tranche One          
Stock-based compensation          
Award vesting period (in years)   1 year      
RSUs awarded in 2009 and after | Share-based Payment Arrangement, Tranche Two          
Stock-based compensation          
Award vesting period (in years)   4 years      
RSUs awarded in 2009 and after | Share-based Payment Arrangement, Tranche Three          
Stock-based compensation          
Award vesting period (in years)   5 years      
Restricted stock units (RSU)          
Stock-based compensation          
Share-based compensation expense   $ 23,700,000 $ 20,800,000 $ 20,200,000  
Deferred vested award (in shares)   0.6      
Granted (in dollars per share)   $ 74.26 $ 66.96 $ 64.33  
Total fair value   $ 23,600,000 $ 27,400,000 $ 30,300,000  
Unrecognized compensation cost   $ 41,700,000      
Unrecognized compensation costs, period for recognition   4 years      
Weighted average life (in years)   1 year 6 months      
Stock options          
Stock-based compensation          
Liability related to forfeitures for tax payments   $ 9,800,000 $ 10,600,000 $ 8,700,000  
Subsequent events          
Stock-based compensation          
Common shares repurchased (in shares) 0.1        
Common shares repurchased, cost $ 3,400,000