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Pension and Other Post-Retirement Benefits - Components of Net Periodic Cost (Benefit) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Defined Benefit Pension [Member] |  |  |  |
Components of pension and other post retirement benefit costs |  |  |  |
Service cost | $ 2.0 | $ 1.7 | $ 6.0 | $ 4.9
Interest cost | 3.1 | 3.8 | 9.2 | 11.4
Expected return on plan assets | (5.0) | (5.6) | (15.1) | (16.6)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) | 3.2 | 1.9 | 9.6 | 5.7
Defined Benefit Plan, Amortization of Prior Service Cost (Credit) | 0.0 |  | 0.0 |
Defined Benefit Plan, Amortization of Gain (Loss) | 3.1 | 2.0 | 9.5 | 6.0
Retiree Health and Life [Member] |  |  |  |
Components of pension and other post retirement benefit costs |  |  |  |
Service cost | 0.0 | 0.0 | 0.1 | 0.1
Interest cost | 0.1 | 0.2 | 0.4 | 0.7
Expected return on plan assets | 0.0 | 0.0 | 0.0 | 0.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) | 0.0 | 0.2 | 0.1 | 0.6
Defined Benefit Plan, Amortization of Prior Service Cost (Credit) | 0.0 | 0.0 | (0.1) | (0.1)
Defined Benefit Plan, Amortization of Gain (Loss) | (0.1) | 0.0 | (0.3) | (0.1)
RRPF Joint Ventures [Member] |  |  |  |
Components of pension and other post retirement benefit costs |  |  |  |
Equity Method Investment. Summarized Financial Data. Net Income | 21.7 | 20.8 | 77.6 | 72.0
Alpha Partners Leasing Limited [Domain] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Equity Method Investment, Summarized Financial Information. Revenue. | 112.5 | 94.0 | 318.5 | 283.5
Components of pension and other post retirement benefit costs |  |  |  |
Equity Method Investment, Summarized Financial Information, Expenses | (95.9) | (75.1) | (271.0) | (227.7)
Equity Method Investment, Summarized Financial Information, Gains (Losses) | $ 10.0 | $ 6.8 | $ 48.2 | $ 33.1

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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 4: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4587-114921 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
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