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Fair Value (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair Value Disclosure [Line Items]
Transfers between Fair Value Hierarchies	$ 0.0	$ 0.0
Allowance for Credit Loss	0.1	0.6
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease)	0.0
Debt Securities, Available-for-Sale, Realized Gain (Loss)	(2.3)	(1.0)
U.S. Treasury debt securities
Fair Value Disclosure [Line Items]
Allowance for Credit Loss		0.0
Corporate/Other debt securities
Fair Value Disclosure [Line Items]
Allowance for Credit Loss	0.1	$ 0.6
Available-for-sale securities, maturities of less than a year	$ 10.9

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Fair Value Disclosure [Line Items]

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Transfers between Fair Value Hierarchies

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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
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Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
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-Section 50
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-9

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Amount of increase (decrease) of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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