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Fair Value - Recurring Fair Value Measures (Details) - USD ($) $ in Millions | Mar. 31, 2022 | Dec. 31, 2021
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Investments [Abstract] |  |  |  |
Available-for-sale Securities, Debt Maturities, within One Year, Fair Value |  | $ 0.8 |  |
Available-for-sale Securities, Debt Maturities, After One Year Through Three Years, Fair Value |  | 2.7 |  |
Available-for-sale Securities, Debt Maturities, After Three Years Through Five Years, Fair Value |  | 1.5 |  |
Available-for-sale Securities, Debt Maturities, After Five Years, Fair Value |  | 0.5 |  |
Recurring Fair Value Measures [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale - Equity Securities | [1] | 8.9 |  | $ 8.9
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 5.5 | [2] | 6.2
Cash Equivalents | [1] | 3.4 |  | 2.5
Total Fair Value of Assets |  | 17.8 |  | 17.6
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 16.5 |  | 18.0
Total Fair Value of Liabilities |  | 16.5 |  | 18.0
Recurring Fair Value Measures [Member] | Level 1 [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale - Equity Securities | [1] | 8.9 |  | 8.9
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 0.0 | [2] | 0.0
Cash Equivalents | [1] | 3.4 |  | 2.5
Total Fair Value of Assets |  | 12.3 |  | 11.4
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 0.0 |  | 0.0
Total Fair Value of Liabilities |  | 0.0 |  | 0.0
Recurring Fair Value Measures [Member] | Level 2 [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale - Equity Securities | [1] | 0.0 |  | 0.0
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 5.5 | [2] | 6.2
Cash Equivalents | [1] | 0.0 |  | 0.0
Total Fair Value of Assets |  | 5.5 |  | 6.2
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 16.5 |  | 18.0
Total Fair Value of Liabilities |  | 16.5 |  | 18.0
Recurring Fair Value Measures [Member] | Level 3 [Member] |  |  |  |
Investments [Abstract] |  |  |  |
Available-for-sale - Equity Securities | [1] | 0.0 |  | 0.0
Available-for-sale – Corporate and Governmental Debt Securities (b) | [1] | 0.0 | [2] | 0.0
Cash Equivalents | [1] | 0.0 |  | 0.0
Total Fair Value of Assets |  | 0.0 |  | 0.0
Liabilities [Abstract] |  |  |  |
Deferred Compensation | [3] | 0.0 |  | 0.0
Total Fair Value of Liabilities |  | $ 0.0 |  | $ 0.0
[1] | Included in Other Non-Current Assets on the Consolidated Balance Sheet.
[2] | As of March 31, 2022, the aggregate amount of available-for-sale corporate and governmental debt securities maturing in one year or less was $0.8 million, in one year to less than three years was $2.7 million, in three years to less than five years was $1.5 million and in five or more years was $0.5 million.
[3] | Included in Other Non-Current Liabilities on the Consolidated Balance Sheet.

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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123599081&loc=SL120269850-112803 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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