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Pension and Other Postretirement Benefits (Schedule Of Fair Value Of Pension Plan Assets) (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
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Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | $ 436.3 |
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | $ 480.4 |  |
Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 934.4 | 968.6 |
Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 | $ 86.1
Fair Value, Inputs, Level 1, 2 and 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 2,404.1 | 2,342.3 |
Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 | 18.5
Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 | 12.5
Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 | 2.4
Pension Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Accumulated Benefit Obligation | 2,036.8 | 2,111.5 |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 2,110.7 | 2,073.0 |
Defined Benefit Plan, Benefit Obligation | 2,058.4 | 2,130.5 | 1,981.3
Defined Benefit Plan, Funded (Unfunded) Status of Plan | 59.3 | (49.6) |
Pension Plan | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items |  | 204.1 |
Pension Plan | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 231.1 |  |
Pension Plan | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 936.0 | 971.4 |
Pension Plan | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 0.0 | 0.0 |
Pension Plan | Fair Value, Inputs, Level 1, 2 and 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 2,117.7 | 2,080.9 | 1,867.7
Pension Plan | Cash [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 11.9 | 6.7 |
Pension Plan | Cash [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 6.7 |
Pension Plan | Cash [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 11.9 |  |
Pension Plan | Cash [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Cash [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | International Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 230.1 | 205.0 |
Pension Plan | Fixed Income |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 1,291.2 | 1,337.2 |
Pension Plan | Equity Securities [Member] | United States Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 2.4 |  |
Pension Plan | Equity Securities [Member] | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 2.4 |  |
Pension Plan | Equity Securities [Member] | United States Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Equity Securities [Member] | United States Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Fixed Income Securities [Member] | Government |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 243.4 | 319.6 |
Pension Plan | Fixed Income Securities [Member] | Government | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Fixed Income Securities [Member] | Government | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Fixed Income Securities [Member] | Government | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 243.4 | 319.6 |
Pension Plan | Fixed Income Securities [Member] | Government | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Fixed Income Securities [Member] | Corporate [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 692.6 | 651.8 |
Pension Plan | Fixed Income Securities [Member] | Corporate [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Fixed Income Securities [Member] | Corporate [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Fixed Income Securities [Member] | Corporate [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 692.6 | 651.8 |
Pension Plan | Fixed Income Securities [Member] | Corporate [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | International Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 176.8 | 148.1 |
Pension Plan | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Commingled Funds | International Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | International Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | Fixed Income |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 337.6 | 351.8 |
Pension Plan | Commingled Funds | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Commingled Funds | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Commingled Funds | Fixed Income | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | Fixed Income | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | United States Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 279.7 | 305.9 |
Pension Plan | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Commingled Funds | United States Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | United States Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | Short-Term Money Markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 78.8 | 14.8 |
Pension Plan | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Commingled Funds | Short-Term Money Markets | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Commingled Funds | Short-Term Money Markets | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 10.9 | 14.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | U.S. Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 6.6 | 8.5 |
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | International Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.3 | 0.5 |
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Private Equity Limited Partnerships [Member] | Distressed Opportunities [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Real Estate [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 52.9 | 53.9 |
Pension Plan | Real Estate [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Pension Plan | Real Estate [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Real Estate [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Real Estate [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Mutual Funds [Member] | International Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 55.4 | 56.9 |
Pension Plan | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 56.9 |
Pension Plan | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 55.4 |  |
Pension Plan | Mutual Funds [Member] | International Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Mutual Funds [Member] | International Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 161.3 | 140.5 |
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 140.5 |
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 161.3 |  |
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Mutual Funds [Member] | U.S. Multi-Strategy [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Pension Plan | Mutual Funds [Member] | Fixed Income |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.1 |  |
Pension Plan | Mutual Funds [Member] | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.1 |  |
Pension Plan | Mutual Funds [Member] | Fixed Income | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Pension Plan | Mutual Funds [Member] | Fixed Income | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Other Postretirement Benefits |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 286.4 | 261.4 |
Defined Benefit Plan, Benefit Obligation | 590.8 | 576.5 | 492.5
Defined Benefit Plan, Funded (Unfunded) Status of Plan | (304.4) | (315.1) |
Other Postretirement Benefits | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items |  | 221.5 |
Other Postretirement Benefits | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 240.7 |  |
Other Postretirement Benefits | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 0.0 | 0.0 |
Other Postretirement Benefits | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items | 0.0 | 0.0 |
Other Postretirement Benefits | Fair Value, Inputs, Level 1, 2 and 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 286.4 | 261.4 | $ 216.3
Other Postretirement Benefits | International Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 48.2 | 40.7 |
Other Postretirement Benefits | Fixed Income |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 122.0 | 119.5 |
Other Postretirement Benefits | Due To Brokers Net [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | (1.6) | (2.8) |
Other Postretirement Benefits | Due To Brokers Net [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Other Postretirement Benefits | Due To Brokers Net [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Other Postretirement Benefits | Due To Brokers Net [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | (1.6) | (2.8) |
Other Postretirement Benefits | Due To Brokers Net [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Accrued Investment Income Dividends [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 10.7 |
Other Postretirement Benefits | Accrued Investment Income Dividends [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 10.7 |
Other Postretirement Benefits | Accrued Investment Income Dividends [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Other Postretirement Benefits | Accrued Investment Income Dividends [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Other Postretirement Benefits | Receivables/Payables [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 8.6 |  |
Other Postretirement Benefits | Receivables/Payables [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 8.6 |  |
Other Postretirement Benefits | Receivables/Payables [Member] | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Other Postretirement Benefits | Receivables/Payables [Member] | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Other Postretirement Benefits | Commingled Funds | International Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 24.1 | 20.1 |
Other Postretirement Benefits | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Other Postretirement Benefits | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Other Postretirement Benefits | Commingled Funds | International Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Commingled Funds | International Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Commingled Funds | United States Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 14.0 | 12.1 |
Other Postretirement Benefits | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Other Postretirement Benefits | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Other Postretirement Benefits | Commingled Funds | United States Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Commingled Funds | United States Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 7.6 | 7.7 |
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 0.0 |
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 |  |
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Mutual Funds [Member] | International Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 24.1 | 20.6 |
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 20.6 |
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 24.1 |  |
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Mutual Funds [Member] | International Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 121.8 | 119.2 |
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 119.2 |
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 121.8 |  |
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Mutual Funds [Member] | Fixed Income | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 94.8 | 81.7 |
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount |  | 81.7 |
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member] | Fair Value, Recurring |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 94.8 |  |
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Significant Other Observable Inputs (Level 2) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Other Postretirement Benefits | Mutual Funds [Member] | United States Equities | Significant Unobservable Inputs (Level 3) [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 0.0 |
Underfunded Plan [Member] | Pension Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Accumulated Benefit Obligation | 2,004.7 | 637.6 |
Defined Benefit Plan, Plan Assets, Amount | 2,117.7 | 645.8 |
Defined Benefit Plan, Benefit Obligation | 2,026.3 | 637.6 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | 91.4 | 8.2 |
Underfunded Plan [Member] | Pension Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined Benefit Plan, Accumulated Benefit Obligation | 32.1 | 1,473.9 |
Defined Benefit Plan, Plan Assets, Amount | 0.0 | 1,435.1 |
Defined Benefit Plan, Benefit Obligation | 32.1 | 1,492.9 |
Defined Benefit Plan, Funded (Unfunded) Status of Plan | $ (32.1) | $ (57.8) |

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