XML 54 R43.htm IDEA: XBRL DOCUMENT v3.21.2
Income Taxes -Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Jun. 30, 2021
Jun. 30, 2020
Sep. 30, 2020
Income Tax Disclosure [Abstract]          
Effective income tax rate 19.50% 15.90% 16.70% 1.80%  
Unrecognized tax benefits, uncertain tax positions $ 12.1   $ 12.1   $ 8.0
Unrecognized tax benefits, accrued interest $ 0.6   $ 0.6   $ 0.4