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v3.25.3

Employee Benefit Plans - Pension and Other Postretirement Benefit Costs (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023
Pension benefits |  |  |
Net periodic benefit costs (income) |  |  |
Interest cost | $ 69.9 | $ 83.4 | $ 81.8
Expected return on plan assets | (71.8) | (68.4) | (66.9)
Amortization of prior service costs (credits) | 0.1 | 0.1 | 0.1
Actuarial loss (gain) | 26.2 | (5.1) | (35.0)
Net periodic benefit costs (income) | $ 24.4 | $ 10.0 | $ (20.0)
Weighted-average plan assumptions |  |  |
Discount rate for interest cost | 4.65% | 5.92% | 5.45%
Expected long-term rate of return on plan assets | 5.20% | 5.30% | 4.90%
Other postretirement benefits |  |  |
Net periodic benefit costs (income) |  |  |
Interest cost | $ 1.0 | $ 1.2 | $ 1.2
Expected return on plan assets | 0.0 | 0.0 | 0.0
Amortization of prior service costs (credits) | (2.2) | (2.2) | (2.2)
Actuarial loss (gain) | 0.4 | 2.7 | (6.6)
Net periodic benefit costs (income) | $ (0.8) | $ 1.7 | $ (7.6)
Weighted-average plan assumptions |  |  |
Discount rate for interest cost | 4.63% | 5.92% | 5.41%

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