Quarterly report pursuant to Section 13 or 15(d)

Retirement Benefits - Narrative (Details)

v3.21.1
Retirement Benefits - Narrative (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Mar. 31, 2021
Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]        
Defined Contribution Plan, Cost $ 2.9 $ 3.8 $ 6.6 $ 7.1