Investments (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Fair Values of Fixed Maturity Securities

At December 31, 2023, the Company’s amortized cost and fair values of fixed maturity securities are summarized as follows:

(in millions)	Cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. Treasury securities, obligations of    U.S. Government agencies and Municipalities	$	25.5	$	—	$	(1.1	)	$	24.4
Corporate debt		4.8		—		(0.1	)		4.7
Total	$	30.3	$	—	$	(1.2	)	$	29.1

At December 31, 2022, the Company’s amortized cost and fair values of fixed maturity securities are summarized as follows:

(in millions)	Cost		Gross unrealized gains		Gross unrealized losses			Fair value
U.S. Treasury securities, obligations of    U.S. Government agencies and Municipalities	$	22.8	$	—	$	(1.8	)	$	21.0
Corporate debt		8.2		—		(0.4	)		7.8
Total	$	31.0	$	—	$	(2.2	)	$	28.8

Schedule of Investments' Gross Unrealized Loss and Fair Value

For securities in a loss position, the following table shows the investments’ gross unrealized loss and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2023:

	Less than 12 Months				12 Months or More					Total
(in millions)	Fair value		Unrealized losses		Fair value		Unrealized losses			Fair value		Unrealized losses
U.S. Treasury securities, obligations of U.S.    Government agencies and Municipalities	$	1.4	$	—	$	18.4	$	(1.1	)	$	19.8	$	(1.1	)
Corporate debt		—		—		4.7		(0.1	)		4.7		(0.1	)
Total	$	1.4	$	—	$	23.1	$	(1.2	)	$	24.5	$	(1.2	)

The following table shows the investments’ gross unrealized loss and fair value, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position as of December 31, 2022:

	Less than 12 Months					12 Months or More					Total
(in millions)	Fair value		Unrealized losses			Fair value		Unrealized losses			Fair value		Unrealized losses
U.S. Treasury securities, obligations of    U.S. Government agencies and Municipalities	$	4.7	$	(0.1	)	$	16.3	$	(1.7	)	$	21.0	$	(1.8	)
Corporate debt		4.2		(0.1	)		3.6		(0.3	)		7.8		(0.4	)
Total	$	8.9	$	(0.2	)	$	19.9	$	(2.0	)	$	28.8	$	(2.2	)

Amortized Cost and Fair Value of Fixed Maturity Securities by Contractual Maturity

The amortized cost and estimated fair value of the fixed maturity securities at December 31, 2023 by contractual maturity are set forth below:

(in millions)	Amortized cost		Fair value
Years to maturity:
Due in one year or less	$	10.9	$	10.6
Due after one year through five years		19.4		18.5
Due after five years through ten years		—		—
Total	$	30.3	$	29.1

The amortized cost and estimated fair value of the fixed maturity securities at December 31, 2022 by contractual maturity are set forth below:

(in millions)	Amortized cost		Fair value
Years to maturity:
Due in one year or less	$	6.5	$	6.4
Due after one year through five years		24.5		22.4
Due after five years through ten years		—		—
Total	$	31.0	$	28.8