Fair Value Measurements - Schedule of Changes in Level 3 Assets (Details) - Debt Securities - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 0.0	$ 0.0	$ 0.0	$ 0.0
Purchases and commitments funded	15.1	0.0	15.1	0.0
Sales and distributions	0.0	0.0	0.0	0.0
Net realized and unrealized losses(1)	(0.2)	0.0	(0.2)	0.0
Balance, end of period	14.9	0.0	14.9	0.0
Net change in unrealized losses relating to instruments still held at the reporting date	$ (0.2)	$ 0.0	$ (0.2)	$ 0.0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases and Issuances

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- Definition

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements and Reductions

+ References

No definition available.

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- Definition

Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

+ References

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-Topic 820
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
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- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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-Topic 820
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