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Pension and Postretirement Benefit Costs - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined Benefit Plan, Net Mark-To-Market Adjustment on Actuarially Determined Liabilities | $ 0.0 | $ 13.0 | $ 0.0 | $ 13.0
Defined Benefit Plan, Benefit Obligation | $ 160.0 |  | $ 160.0 |
Defined benefit pension plans |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Funding threshold | 80.00% |  | 80.00% |

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- Definition Defined Benefit Plan, Net Mark-To-Market Adjustment on Actuarially Determined Liabilities + References No definition available. + Details
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- Definition Percentage of company's qualified pension plans on a GAAP accounting basis. + References No definition available. + Details
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- Definition Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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- Details
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