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Fair Value (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Mar. 31, 2023 | Jun. 30, 2023 | Dec. 31, 2022
Fair Value Disclosure [Line Items] |  |  |
Transfers between Fair Value Hierarchies | $ 0.0 | $ 0.0 |
Allowance for Credit Loss |  | 0.7 | $ 0.9
U.S. Treasury debt securities |  |  |
Fair Value Disclosure [Line Items] |  |  |
Allowance for Credit Loss |  | 0.0 | 0.0
Available-for-sale Securities, Maturities, Next Twelve Months, Fair Value |  | 12.9 |
Corporate/Other debt securities |  |  |
Fair Value Disclosure [Line Items] |  |  |
Allowance for Credit Loss |  | 0.7 | $ 0.9
Available-for-sale Securities, Maturities, Next Twelve Months, Fair Value |  | $ 3.6 |

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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 -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 320 -Name Accounting Standards Codification -Section 50 -Paragraph 3A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480832/942-320-50-3A + Details
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