Investments (Tables)

3 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Amortized cost and fair values

The following tables present cost or amortized cost and fair values of investment in fixed maturities as of March 31, 2024 and December 31, 2023 ($ in millions):

	Cost or Amortized Cost		Gross Unrealized				Fair Value
			Gains		Losses
March 31, 2024
Corporate debt securities	$	454.6	$	0.6	$	(3.5)	$	451.7
U.S. Government obligations	164.4		0.1		(0.9)		163.6
Asset-backed securities	4.5		—		—		4.5
Total	$	623.5	$	0.7	$	(4.4)	$	619.8
December 31, 2023
Corporate debt securities	$	453.6	$	1.3	$	(5.0)	$	449.9
U.S. Government obligations	176.8		0.4		(1.3)		175.9
Asset-backed securities	1.6		—		—		1.6
Total	$	632.0	$	1.7	$	(6.3)	$	627.4

Contractual maturities of bonds

The following table presents the cost or amortized cost and estimated fair value of investments in fixed maturities as of March 31, 2024 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.

	March 31, 2024
	Cost or Amortized Cost		Fair Value
Due in one year or less	$	225.1	$	223.7
Due after one year through five years	398.4		396.1
Due after five years through ten years	—		—
Due after ten years	—		—
Total	$	623.5	$	619.8

Net investment income

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

	Three Months Ended March 31,
	2024		2023
Interest on cash and cash equivalents	$	1.5	$	1.2
Fixed maturities	5.8		2.9
Short-term investments	0.4		1.0
Total	7.7		5.1
Investment expense	0.1		0.1
Net investment income	$	7.6	$	5.0

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 March 31, 2024 and December 31, 2023 ($ 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
March 31, 2024
Corporate debt securities	$	141.5	$	(0.6)	$	165.8	$	(2.9)	$	307.3	$	(3.5)
U.S. Government obligations	64.5		(0.6)		48.6		(0.3)		113.1		(0.9)
Asset-backed securities	1.2		—		0.1		—		1.3		—
Total	$	207.2	$	(1.2)	$	214.5	$	(3.2)	$	421.7	$	(4.4)

	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, 2023
Corporate debt securities	$	89.0	$	(1.2)	$	178.3	$	(4.0)	$	267.3	$	(5.2)
U.S. Government obligations	79.6		(0.2)		57.7		(0.9)		137.3		(1.1)
Asset-backed securities	—		—		0.2		—		0.2		—
Total	$	168.6	$	(1.4)	$	236.2	$	(4.9)	$	404.8	$	(6.3)