Employee Benefit Plans (Details) $ / shares in Units, $ in Millions	3 Months Ended
Dec. 31, 2024 USD ($) grant_recipient $ / shares shares	Dec. 31, 2023 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Noncash Expense	$ 43.0	$ 40.9
Performance Shares [Member] \| October Two Thousand Twenty Four Grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs granted in the period \| shares	327,717
Award vesting period	3 years
Share-based Payment Arrangement, Noncash Expense	$ 4.8
Fair value of equity awards on the date of grant (in US$ per unit) \| $ / shares	$ 176.39
Performance Shares [Member] \| October Two Thousand Twenty Four Grant \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of total units granted that vest in the period	0.00%
Performance Shares [Member] \| October Two Thousand Twenty Four Grant \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of total units granted that vest in the period	300.00%
Time-Based RSU \| First Quarter Two Thousand Twenty Five time-based RSU Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs granted in the period \| shares	610,000
Share-based Payment Arrangement, Noncash Expense	$ 10.8
Fair value of equity awards on the date of grant (in US$ per unit) \| $ / shares	$ 156.12
RSU Grant Recipients \| grant_recipient	1,600
Time-Based RSU \| First Quarter Two Thousand Twenty Five time-based RSU Grants \| Retirement Eligible
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Noncash Expense	$ 8.3
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Noncash Expense	$ 40.1	$ 37.3

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