Pension and Other Postretirement Benefits - Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions |
12 Months Ended |
Sep. 30, 2024 |
Sep. 30, 2023 |
Sep. 30, 2022 |
| Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract] |
|
|
|
| Net (gain) loss |
$ 7.8
|
$ (3.4)
|
$ 24.0
|
| Pension Benefits | UNITED STATES |
|
|
|
| Weighted-average assumptions used to determine net benefit cost [Abstract] |
|
|
|
| Discount rate |
6.06%
|
5.65%
|
3.05%
|
| Rate of compensation increase |
3.00%
|
3.00%
|
3.00%
|
| Expected return on plan assets |
7.00%
|
6.50%
|
5.75%
|
| Pension Benefits | SERP |
|
|
|
| Weighted-average assumptions used to determine net benefit cost [Abstract] |
|
|
|
| Discount rate |
5.99%
|
|
|
| Pension Benefits | Other international |
|
|
|
| Components of net periodic benefit cost [Abstract] |
|
|
|
| Service cost |
$ 0.3
|
$ 0.0
|
$ 0.0
|
| Interest cost |
25.6
|
23.3
|
15.7
|
| Expected return on plan assets |
(34.7)
|
(30.8)
|
(24.8)
|
| Recognized net actuarial (gain) loss |
0.1
|
(0.1)
|
0.0
|
| Recognized prior service cost |
0.5
|
0.4
|
0.4
|
| Net periodic benefit cost (income) |
$ (8.2)
|
$ (7.0)
|
$ (8.7)
|
| Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Weighted-average assumptions used to determine net benefit cost [Abstract] |
|
|
|
| Discount rate |
5.67%
|
5.15%
|
2.05%
|
| Rate of compensation increase |
3.02%
|
3.85%
|
3.45%
|
| Expected return on plan assets |
6.26%
|
5.63%
|
2.73%
|
| Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract] |
|
|
|
| Net (gain) loss |
$ 2.6
|
$ 7.6
|
$ 46.2
|
| Recognized gain (loss) |
(0.1)
|
(0.1)
|
0.0
|
| Plan inception |
0.1
|
0.0
|
0.0
|
| Recognized prior service cost |
(0.5)
|
(0.4)
|
(0.4)
|
| Total recognized in other comprehensive income or loss (before tax effects) |
2.1
|
7.1
|
45.8
|
| Pension Benefits | North America |
|
|
|
| Components of net periodic benefit cost [Abstract] |
|
|
|
| Service cost |
2.5
|
2.2
|
4.3
|
| Interest cost |
5.8
|
5.3
|
3.5
|
| Expected return on plan assets |
(8.1)
|
(7.5)
|
(7.0)
|
| Recognized net actuarial (gain) loss |
(0.5)
|
(0.2)
|
1.6
|
| Recognized prior service cost |
0.7
|
0.1
|
0.1
|
| Net periodic benefit cost (income) |
$ 0.4
|
$ (0.1)
|
$ 2.5
|
| Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Expected Return (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Amortization of Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract] |
|
|
|
| Net (gain) loss |
$ (5.7)
|
$ (8.0)
|
$ (4.7)
|
| Recognized gain (loss) |
0.5
|
0.2
|
(1.6)
|
| Plan inception |
8.3
|
0.0
|
0.0
|
| Recognized prior service cost |
(0.7)
|
(0.1)
|
(0.1)
|
| Total recognized in other comprehensive income or loss (before tax effects) |
$ 2.4
|
$ (7.9)
|
$ (6.4)
|
| Pension Benefits | CANADA |
|
|
|
| Weighted-average assumptions used to determine net benefit cost [Abstract] |
|
|
|
| Discount rate |
5.68%
|
5.12%
|
3.32%
|
| Rate of compensation increase |
2.75%
|
2.75%
|
2.75%
|
| Expected return on plan assets |
6.00%
|
5.75%
|
5.25%
|
| Other Benefits | UNITED STATES |
|
|
|
| Weighted-average assumptions used to determine net benefit cost [Abstract] |
|
|
|
| Discount rate |
6.01%
|
5.62%
|
2.89%
|
| Other Benefits | North America |
|
|
|
| Components of net periodic benefit cost [Abstract] |
|
|
|
| Service cost |
$ 0.2
|
$ 0.3
|
$ 0.5
|
| Interest cost |
2.7
|
2.5
|
1.5
|
| Recognized net actuarial (gain) loss |
(1.0)
|
(0.5)
|
0.6
|
| Recognized prior service cost |
(0.6)
|
(4.7)
|
(4.6)
|
| Net periodic benefit cost (income) |
$ 1.3
|
$ (2.4)
|
$ (2.0)
|
| Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Amortization of Prior Service Cost (Credit), Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] |
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
Other Nonoperating Income (Expense)
|
| Changes in plan assets and benefit obligation recognized in other comprehensive income or loss [Abstract] |
|
|
|
| Net (gain) loss |
$ 2.5
|
$ (3.0)
|
$ (17.5)
|
| Recognized gain (loss) |
1.0
|
0.5
|
(0.6)
|
| Recognized prior service cost |
0.6
|
4.7
|
4.6
|
| Total recognized in other comprehensive income or loss (before tax effects) |
$ 4.1
|
$ 2.2
|
$ (13.5)
|
| Other Benefits | CANADA |
|
|
|
| Weighted-average assumptions used to determine net benefit cost [Abstract] |
|
|
|
| Discount rate |
5.67%
|
5.12%
|
3.45%
|
| Rate of compensation increase |
2.75%
|
2.75%
|
2.75%
|