Investments (Tables)

6 Months Ended

Jun. 30, 2026

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost and Fair Values of Investment in Fixed Maturities

The following tables present cost or amortized cost and fair values of investment in fixed maturities as of June 30, 2026 and December 31, 2025 ($ in millions):

	Cost or Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
June 30, 2026
Corporate debt securities	$	503.4	$	0.1	$	(2.1)	$	501.4
U.S. Government obligations	157.5		—		(1.5)		156.0
Asset-backed securities and collateralized loan obligations	82.5		—		(0.3)		82.2
Non-U.S. government obligations	29.0		—		(0.1)		28.9
Total	$	772.4	$	0.1	$	(4.0)	$	768.5
December 31, 2025
Corporate debt securities	$	499.2	$	2.0	$	—	$	501.2
U.S. Government obligations	139.5		0.6		—		140.1
Asset-backed securities	45.3		0.2		—		45.5
Non-U.S. government obligations	22.0		—		—		22.0
Total	$	706.0	$	2.8	$	—	$	708.8

Schedule of Contractual Maturities of Bonds

The following table presents the cost or amortized cost and estimated fair value of investments in fixed maturities as of June 30, 2026 by contractual maturity ($ in millions). Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

	June 30, 2026
	Cost or Amortized Cost		Fair Value
Due in one year or less	$	100.8	$	100.9
Due after one year through five years	589.1		585.4
Due after five years through ten years	—		—
Due after ten years	—		—
Sub-total	689.9		686.3
Asset-backed securities and collateralized loan obligations	82.5		82.2
Total	$	772.4	$	768.5

Schedule of Net Investment Income

Details of the Company's net investment income is as follows ($ in millions):

	Three Months Ended June 30,				Six Months Ended June 30,
	2026		2025		2026		2025
Interest on cash and cash equivalents	$	1.9	$	2.1	$	4.0	$	4.2
Fixed maturities	7.8		7.2		15.5		14.4
Short-term investments	0.1		0.2		0.2		0.5
Total	9.8		9.5		19.7		19.1
Investment expense	0.1		0.1		0.2		0.2
Net investment income	$	9.7	$	9.4	$	19.5	$	18.9

Schedule of Aging of Gross Unrealized losses

The following table presents the gross unrealized losses and related fair values for the Company’s investment in fixed maturities, grouped by duration of time in a continuous unrealized loss position as of June 30, 2026 and December 31, 2025 ($ in millions):

	Less than 12 Months				12 Months or More				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
June 30, 2026
Corporate debt securities	$	411.6	$	(2.1)	$	—	$	—	$	411.6	$	(2.1)
U.S. Government obligations	144.2		(1.5)		—		—		144.2		(1.5)
Asset-backed securities and collateralized loan obligations	63.4		(0.3)		—		—		63.4		(0.3)
Non-U.S. government obligations	21.0		(0.1)		—		—		21.0		(0.1)
Total	$	640.2	$	(4.0)	$	—	$	—	$	640.2	$	(4.0)

	Less than 12 Months				12 Months or More				Total
	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
December 31, 2025
Corporate debt securities	$	45.9	$	—	$	4.9	$	—	$	50.8	$	—
U.S. Government obligations	0.4		—		—		—		0.4		—
Asset-backed securities	—		—		—		—		—		—
Non-U.S. government obligations	7.2		—		—		—		7.2		—
Total	$	53.5	$	—	$	4.9	$	—	$	58.4	$	—