Investments (Tables)

12 Months Ended

Dec. 31, 2023

Summary of Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Available-for-Sale Securities

The Company holds investments in fixed-maturity securities that are classified as available-for-sale. At December 31, 2023 and 2022, the cost or amortized cost, allowance for credit loss, gross unrealized gains and losses, and estimated fair value of the Company’s available-for-sale securities by security type were as follows:

	Cost or Amortized		Allowance  for		Gross Unrealized		Gross Unrealized			Estimated Fair
	Cost		Credit Loss		Gain		Loss			Value
As of December 31, 2023
U.S. Treasury and U.S. government agencies	$	359,630	$	—	$	224	$	(3,800	)	$	356,054
Corporate bonds		27,563		—		116		(975	)		26,704
Exchange-traded debt		494		—		—		(14	)		480
Total	$	387,687	$	—	$	340	$	(4,789	)	$	383,238
As of December 31, 2022
U.S. Treasury and U.S. government agencies	$	463,648	$	—	$	59	$	(9,105	)	$	454,602
Corporate bonds		28,378		—		20		(1,205	)		27,193
State, municipalities, and political subdivisions		1,389		—		—		(6	)		1,383
Exchange-traded debt		683		—		2		(52	)		633
Redeemable preferred stock		99		—		—		(9	)		90
Total	$	494,197	$	—	$	81	$	(10,377	)	$	483,901

Scheduled Contractual Maturities of Fixed-Maturity Securities

The scheduled contractual maturities of fixed-maturity securities at December 31, 2023 and 2022 are as follows:

	December 31,
	2023				2022
	Cost or		Estimated		Cost or		Estimated
	Amortized		Fair		Amortized		Fair
	Cost		Value		Cost		Value
Available-for-sale
Due in one year or less	$	234,992	$	234,025	$	266,170	$	265,353
Due after one year through five years		148,935		145,758		223,153		214,307
Due after five years through ten years		3,266		2,974		4,380		3,797
Due after ten years		494		481		494		444
	$	387,687	$	383,238	$	494,197	$	483,901

Summary of Proceeds Received and Gross Realized Gains and Losses from Sales of Available-for-Sale Securities

Proceeds received, and the gross realized gains and losses from sales of available-for-sale fixed-maturity securities, for the years ended December 31, 2023, 2022 and 2021 were as follows:

			Gross		Gross
			Realized		Realized
	Proceeds		Gains		Losses
Year ended December 31, 2023	$	22,326	$	7	$	(1,036	)
Year ended December 31, 2022	$	11,716	$	13	$	(442	)
Year ended December 31, 2021	$	23,055	$	722	$	(35	)

Summary of Securities with Gross Unrealized Loss Positions Aggregated by Investment Category

Securities with gross unrealized loss positions at December 31, 2023 and 2022, aggregated by investment category and length of time the individual securities have been in a continuous loss position, are as follows:

	Less Than Twelve Months					Twelve Months or Longer					Total
As of December 31, 2023	Gross Unrealized Loss			Estimated Fair Value		Gross Unrealized Loss			Estimated Fair Value		Gross Unrealized Loss			Estimated Fair Value
U.S. Treasury and U.S. government agencies	$	(22	)	$	3,464	$	(3,778	)	$	181,463	$	(3,800	)	$	184,927
Corporate bonds		(8	)		1,941		(967	)		19,418		(975	)		21,359
Exchange-traded debt		(14	)		481		—			—		(14	)		481
Total available-for-sale securities	$	(44	)	$	5,886	$	(4,745	)	$	200,881	$	(4,789	)	$	206,767

	Less Than Twelve Months					Twelve Months or Longer					Total
As of December 31, 2022	Gross Unrealized Loss			Estimated Fair Value		Gross Unrealized Loss			Estimated Fair Value		Gross Unrealized Loss			Estimated Fair Value
U.S. Treasury and U.S. government agencies	$	(8,701	)	$	269,116	$	(404	)	$	4,644	$	(9,105	)	$	273,760
Corporate bonds		(909	)		23,028		(296	)		2,541		(1,205	)		25,569
States, municipalities, and political    subdivisions		(6	)		1,383		—			—		(6	)		1,383
Exchange-traded debt		(52	)		463		—			—		(52	)		463
Redeemable preferred stock		(9	)		90		—			—		(9	)		90
Total available-for-sale securities	$	(9,677	)	$	294,080	$	(700	)	$	7,185	$	(10,377	)	$	301,265

Summary of Allowance for Credit Losses of Available-for-Sale Securities

The table below summarizes the activity in the allowance for credit losses of available-for-sale fixed-maturity securities for the years ended December 31, 2023, 2022 and 2021:

	2023		2022		2021
Balance at January 1	$	—	$	—	$	588
Reductions for securities sold		—		—		(9	)
Reductions for securities exchanged		—		—		(579	)
Balance at December 31	$	—	$	—	$	—

Summary of Cost, Gross Unrealized Gains and Losses, and Estimated Fair Value of Equity Securities

The Company holds investments in equity securities measured at fair values which are readily determinable. At December 31, 2023 and 2022, the cost, gross unrealized gains and losses, and estimated fair value of the Company’s equity securities were as follows:

			Gross Unrealized		Gross Unrealized			Estimated Fair
	Cost		Gain		Loss			Value
December 31, 2023	$	44,011	$	3,945	$	(2,419	)	$	45,537
December 31, 2022	$	36,272	$	2,078	$	(3,767	)	$	34,583

Summary of Unrealized Gains and Losses for Equity Securities

The table below presents the portion of unrealized gains and losses in the Company’s consolidated statements of income related to equity securities still held.

	Years Ended December 31,
	2023			2022			2021
Net gains (losses) recognized	$	2,282		$	(8,149	)	$	5,486
Exclude: Net realized (losses) gains recognized for    securities sold		(933	)		(996	)		4,123
Net unrealized gains (losses) recognized	$	3,215		$	(7,153	)	$	1,363

Summary of Proceeds Received, Gross Realized Gains and Losses from Sales of Equity Securities

Proceeds received, and the gross realized gains and losses from sales of equity securities, for the years ended December 31, 2023, 2022 and 2021 were as follows:

			Gross Realized		Gross Realized
	Proceeds		Gains		Losses
Year ended December 31, 2023	$	12,202	$	500	$	(1,433	)
Year ended December 31, 2022	$	31,605	$	2,224	$	(3,220	)
Year ended December 31, 2021	$	112,310	$	6,280	$	(2,157	)

Schedule of Company's Investments in Limited Partnerships

The following table provides information related to the Company’s investments in limited partnerships:

	December 31, 2023						December 31, 2022
	Carrying		Unfunded				Carrying		Unfunded
Investment Strategy	Value		Balance		(%) (a)		Value		Balance		(%) (a)
Primarily in senior secured loans and, to    a limited extent, in other debt and    equity securities of private U.S. lower-    middle-market companies. (b)(c)(e)	$	3,295	$	—		15.37	$	4,146	$	—		15.37
Value creation through active distressed    debt investing primarily in bank loans,    public and private corporate bonds,    asset-backed securities, and equity    securities received in connection with    debt restructuring. (b)(d)(e)		2,271		—		1.25		2,528		—		1.66
High returns and long-term capital    appreciation through investments in    the power, utility and energy industries,    and in the infrastructure sector. (b)(f)(g)		3,400		—		0.18		5,319		—		0.18
Value-oriented investments in less liquid    and mispriced senior and junior debts    of private equity-backed companies.    (b)(h)(i)		3,306		—		0.55		3,470		—		0.56
Value-oriented investments in mature real    estate private equity funds and portfolios    globally. (b)(j)		7,590		2,543		1.32		7,457		3,125		1.32
Risk-adjusted returns on credit and equity    investments, primarily in private    equity-owned companies. (b)(k)		3,721		1,662		0.55		2,782		2,536		0.98
Total	$	23,583	$	4,205			$	25,702	$	5,661

(a)Represents the Company’s percentage investment in the fund at each balance sheet date.

(b)Except under certain circumstances, withdrawals from the funds or any assignments are not permitted. Distributions, except income from late admission of a new limited partner, will be received when underlying investments of the funds are liquidated.

(c)The term is expected to be two years following the maturity of the fund’s outstanding leverage. Although the capital commitment period has expired, follow-on investments and pending commitments may require additional fundings.

(d)Effective July 1, 2023, this investment is in the process of winding down. Although the capital commitment period has ended, the general partner could still request an additional funding under certain circumstances.

(e)At the fund manager’s discretion, the term of the fund may be extended for up to two additional one-year periods.

(f)Expected to have a ten-year term. The capital commitment period has expired but the general partner may request additional funding for follow-on investment.

(g)With the consent of a supermajority of partners, the term of the fund may be extended for up to three additional one-year periods.

(h)Expected to have an eight-year term from the commencement date, which can be extended for up to two additional one-year periods with the consent of either the advisory committee or a majority of limited partners.

(i)The capital commitment period has ended but an additional funding may be requested.

(j)The term is expected to end November 27, 2027. The term may be extended for up to four additional one-year periods at the general partner’s discretion, and up to two additional one-year periods with the consent of the advisory committee.

(k)Expected to have an eight-year term after the final admission date. The term may be extended for an additional one-year period at the general partner’s discretion, and up to two additional one-year periods with the consent of either the advisory committee or a majority of limited partners.

Summary of Unaudited Financial Information and Unaudited Financial Position

The following table summarizes the assets related to CORE which are included in the accompanying consolidated balance sheets:

	December 31,
	2023		2022
Assets:
Cash and cash equivalent	$	24,635	$	—
Restricted cash		300		—
Other assets		65		—

Summary of Real Estate Investments

Real estate investments consist of the following as of December 31, 2023 and 2022:

	December 31,
	2023			2022
Land	$	42,272		$	38,327
Land improvements		4,387			12,138
Buildings and building improvements		18,594			29,410
Tenant and leasehold improvements		1,869			1,742
Other		7,168			1,649
Total, at cost		74,290			83,266
Less: accumulated depreciation and amortization		(6,397	)		(11,878	)
Real estate investments	$	67,893		$	71,388

Investment Income (Loss) Summarized

f) Net Investment Income

Net investment income (loss), by source, is summarized as follows:

	Years Ended December 31,
	2023			2022			2021
Available-for-sale fixed-maturity securities	$	17,626		$	6,367		$	1,375
Equity securities		1,551			1,204			1,411
Investment expense		(557	)		(491	)		(542	)
Limited partnership investments		661			3,963			4,947
Real estate investments		10,207			16,126			4,086
Net income from unconsolidated joint venture		—			495			417
Cash and cash equivalents		16,746			4,783			641
Net investment income	$	46,234		$	32,447		$	12,335

Limited Partnership [Member]

Summary of Unaudited Financial Information and Unaudited Financial Position

The following is the summary of aggregated unaudited financial information of limited partnerships included in the investment strategy table above, which in certain cases is presented on a three-month lag due to the unavailability of information at the Company’s respective balance sheet dates. The financial statements of these limited partnerships are audited annually.

	Years Ended December 31,
	2023			2022			2021
Operating results:
Total income*	$	1,606		$	1,252,264		$	705,610
Total expenses		(71,256	)		(139,174	)		(131,463	)
Net (loss) income	$	(69,650	)	$	1,113,090		$	574,147

*Includes net change in unrealized gains or losses on investments.

	December 31,
	2023		2022
Balance sheet:
Total assets	$	4,072,501	$	5,119,695
Total liabilities	$	220,525	$	430,354