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PENSION AND POST-RETIREMENT PLANS - COMPONENTS OF NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Pension Benefits |  |  |  |
Components of Net Periodic Benefit Cost (Benefit): |  |  |  |
Service cost | $ 1.1 | $ 1.1 | $ 3.3 | $ 3.0
Interest cost | 2.1 | 2.5 | 6.4 | 7.3
Expected return on plan assets | (3.3) | (3.3) | (10.1) | (10.1)
Amortization of net loss | 1.0 | 1.3 | 3.4 | 3.8
Amortization of prior service credit | (0.5) | (0.6) | (1.7) | (1.7)
Other adjustments |  | 0.1 |  | 0.1
Net periodic benefit cost | 0.4 | 1.1 | 1.3 | 2.4
Post-retirement Benefits |  |  |  |
Components of Net Periodic Benefit Cost (Benefit): |  |  |  |
Service cost | 0.2 |  | 0.5 | 0.4
Service cost |  | (0.4) |  |
Interest cost | 0.3 |  | 0.8 | 0.8
Interest cost |  | (0.6) |  |
Amortization of net loss | 0.3 | 0.3 | 1.1 | 0.9
Amortization of prior service credit | (1.0) | (2.8) | (2.8) | (2.8)
Net periodic benefit cost | $ (0.2) | $ (3.5) | $ (0.4) | $ (0.7)

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