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Fair Value Measurements (Schedule Of Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions | Jun. 30, 2021 | Dec. 31, 2020
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Supplemental executive retirement plan assets | $ 0.0 | $ 22.6
Total Financial Assets |  | 22.6
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Supplemental executive retirement plan assets |  | 22.6
Total Financial Assets |  | 22.6
Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Supplemental executive retirement plan assets |  | 0.0
Total Financial Assets |  | 0.0
Significant Unobservable Inputs (Level 3) [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Supplemental executive retirement plan assets |  | 0.0
Total Financial Assets |  | $ 0.0

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- Definition The amount of cash, securities, or other assets held by a third-party trustee pursuant to the terms of an agreement which assets are available to be used by beneficiaries to that agreement only within the specific terms thereof and which agreement is expected to terminate more than one year from the balance sheet date (or operating cycle, if longer) at which time the assets held-in-trust will be released or forfeited. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(b)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 + Details
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