Annual report pursuant to Section 13 and 15(d)

Equity - Narrative (Details)

v3.10.0.1
Equity - Narrative (Details) - USD ($)
$ / shares in Units, shares in Millions
 2 Months Ended 12 Months Ended
Nov. 20, 2018
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2016
Jun. 30, 2018
Stock-based compensation          
Shares available for grants (in shares)   1.2      
Total income tax benefit recognized   $ 8,700,000 $ 15,000,000 $ 7,400,000  
Cash paid to satisfy employees personal tax liability   $ 8,529,000 $ 9,175,000 $ 11,614,000  
Stock repurchase programs, authorized amount         $ 200,000,000
Common shares repurchased   1.1 0.6 0.6  
Common shares repurchased, cost   $ 67,572,000 $ 28,863,000 $ 31,338,000  
Amount remaining available for future stock repurchases   $ 192,800,000      
Restricted stock units (RSU)          
Stock-based compensation          
Deferred vested award   0.7      
Granted (in dollars per share)   $ 64.33 $ 53.63 $ 52.00  
Total fair value   $ 30,300,000 $ 24,900,000 $ 27,100,000  
Unrecognized compensation cost   $ 37,200,000      
Expected realization period (in years)   5 years      
Weighted average life (in years)   1 year 7 months      
Share-based compensation expense   $ 20,200,000 21,400,000 18,800,000  
RSUs awarded in 2009 and after | Minimum          
Stock-based compensation          
Award vesting period (in years)   1 year      
RSUs awarded in 2009 and after | Maximum          
Stock-based compensation          
Award vesting period (in years)   5 years      
Stock options          
Stock-based compensation          
Award vesting period (in years)   4 years      
Award expired period   10 years      
Cash paid to satisfy employees personal tax liability   $ 8,700,000 8,700,000 9,300,000  
Share-based compensation expense   $ 0 $ 0 $ 0  
Subsequent events          
Stock-based compensation          
Common shares repurchased 0.2        
Common shares repurchased, cost $ 15,000,000