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Components of Net Periodic Benefit Cost | 3 Months Ended
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Mar. 31, 2019
Components of net periodic benefit cost [Abstract] |
Components of Net Periodic Benefit Cost | Components of Net Periodic Benefit Cost
| Pension Benefits
| Three months ended March 31, |
| 2019 |  | 2018 |
Service cost | $ | 1.1 |  |  | $ | 1.1 |  |
Interest cost | 3.3 |  |  | 3.1 |  |
Expected return on plan assets | (4.9 | ) |  | (5.3 | ) |
Amortization of prior service costs | 0.0 |  | 0.0 |  |
Amortization of net loss | 1.1 |  |  | 1.5 |  |
Net periodic benefit cost | $ | 0.6 |  |  | $ | 0.4 |  |
| Other Postretirement Benefits ("OPEB")
| Three months ended March 31, |
| 2019 |  | 2018 |
Service cost | $ | 0.0 |  |  | $ | 0.1 |  |
Interest cost | 1.0 |  |  | 1.1 |  |
Amortization of prior service cost | (1.3 | ) |  | (1.8 | ) |
Amortization of net loss | 0.8 |  |  | 1.1 |  |
Net periodic benefit cost | $ | 0.5 |  |  | $ | 0.5 |  |

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- Definition Components of net periodic benefit cost [Abstract] + References No definition available. + Details
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- Definition The entire disclosure for pension and other postretirement benefits. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -URI http://asc.fasb.org/topic&trid=2235017 + Details
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