Restricted Securities Available for Sale (Schedule of Restricted Securities Available for Sale) (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Restricted Securities Available For Sale [Line Items]
Total restricted securities available for sale, cost	$ 109.1	$ 105.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.6	1.3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.3	0.1
Debt Securities, Available-for-sale, Restricted	109.4	106.2
Corporate Bond Securities [Member]
Restricted Securities Available For Sale [Line Items]
Total restricted securities available for sale, cost	52.3	53.1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.4	0.9
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.1	0.1
Debt Securities, Available-for-sale, Restricted	52.6	53.9
US Government and Agency Securities [Member]
Restricted Securities Available For Sale [Line Items]
Total restricted securities available for sale, cost	35.9	30.6
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.1	0.2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.2	0.0
Debt Securities, Available-for-sale, Restricted	35.8	30.8
Asset-backed Securities [Member]
Restricted Securities Available For Sale [Line Items]
Total restricted securities available for sale, cost	18.1	18.5
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.1	0.2
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.0
Debt Securities, Available-for-sale, Restricted	18.2	18.7
Mortgage-backed Securities [Member]
Restricted Securities Available For Sale [Line Items]
Total restricted securities available for sale, cost	2.8	2.8
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.0	0.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.0	0.0
Debt Securities, Available-for-sale, Restricted	$ 2.8	$ 2.8

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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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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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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+ Details