Investments (Tables)

9 Months Ended

Sep. 30, 2022

Investments Debt And Equity Securities [Abstract]

Schedule of Disposition of Fixed Income and Equity Securities

Sales	Proceeds		Gross Realized				Net Realized
(in thousands)	From Sales		Gains		Losses		Gain (Loss)
2022
Fixed income securities - available-for-sale	$	48,559	$	286	$	(2,481)	$	(2,195)
Equity securities		59,264		20,410		(609)		19,801
2021
Fixed income securities - available-for-sale	$	43,041	$	1,476	$	(107)	$	1,369
Equity securities		157,973		52,409		(1,787)		50,622
Calls/Maturities			Gross Realized				Net Realized
(in thousands)	Proceeds		Gains		Losses		Gain (Loss)
2022
Fixed income securities - available-for-sale	$	176,991	$	142	$	(55)	$	87
2021
Fixed income securities - available-for-sale	$	296,563	$	471	$	(109)	$	362

Fair Value, Assets Measured on Recurring Basis

	As of September 30, 2022
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs
(in thousands)	(Level 1)		(Level 2)		(Level 3)		Total
Fixed income securities - available-for-sale
U.S. government	$	—	$	340,442	$	—	$	340,442
U.S. agency		—		56,935		—		56,935
Non-U.S. government & agency		—		5,712		—		5,712
Agency MBS		—		317,029		—		317,029
ABS/CMBS/MBS*		—		241,512		—		241,512
Corporate		—		910,979		52,890		963,869
Municipal		—		526,540		—		526,540
Total fixed income securities - available-for-sale	$	—	$	2,399,149	$	52,890	$	2,452,039
Equity securities		461,392		49		1,547		462,988
Total	$	461,392	$	2,399,198	$	54,437	$	2,915,027

	As of December 31, 2021
	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable
	Identical Assets		Inputs		Inputs
(in thousands)	(Level 1)		(Level 2)		(Level 3)		Total
Fixed income securities - available-for-sale
U.S. government	$	—	$	134,554	$	—	$	134,554
U.S. agency		—		32,760		—		32,760
Non-U.S. government & agency		—		8,481		—		8,481
Agency MBS		—		367,187		—		367,187
ABS/CMBS/MBS*		—		264,054		—		264,054
Corporate		—		913,577		43,518		957,095
Municipal		—		645,756		—		645,756
Total fixed income securities - available-for-sale	$	—	$	2,366,369	$	43,518	$	2,409,887
Equity securities		613,712		64		—		613,776
Total	$	613,712	$	2,366,433	$	43,518	$	3,023,663

* Non-agency asset-backed, commercial mortgage-backed and mortgage-backed securities

Summary of Changes in Balance of Level 3 Securities

(in thousands)	Level 3 Securities
Balance as of January 1, 2022	$	43,518
Net realized and unrealized gains (losses)
Included in net earnings as a part of:
Net investment income		(662)
Net realized gains		(433)
Included in other comprehensive earnings (loss)		(8,350)
Total net realized and unrealized gains (losses)	$	(9,445)
Purchases		21,461
Transfers out of Level 3		(1,097)
Balance as of September 30, 2022	$	54,437
Change in unrealized gains (losses) during the period for Level 3 assets held at period-end - included in net realized gains	$	(433)
Change in unrealized gains (losses) during the period for Level 3 assets held at period-end - included in other comprehensive earnings (loss)	$	(8,350)

Schedule of Contractual Maturity of Securities

	September 30, 2022
(in thousands)	Amortized Cost		Fair Value
Due in one year or less	$	206,921	$	206,327
Due after one year through five years		867,511		818,569
Due after five years through 10 years		515,276		457,011
Due after 10 years		526,093		411,591
ABS/CMBS/MBS*		637,830		558,541
Total available-for-sale	$	2,753,631	$	2,452,039

* Asset-backed, commercial mortgage-backed and mortgage-backed securities

Schedule of Amortized Cost and Fair Value of Available-for-sale Securities

	September 30, 2022
	Cost or		Allowance		Gross		Gross
	Amortized		for Credit		Unrealized		Unrealized		Fair
(in thousands)	Cost		Losses		Gains		Losses		Value
U.S. government	$	349,419	$	—	$	—	$	(8,977)	$	340,442
U.S. agency		59,048		—		9		(2,122)		56,935
Non-U.S. government & agency		6,798		—		—		(1,086)		5,712
Agency MBS		360,429		—		172		(43,572)		317,029
ABS/CMBS/MBS*		277,401		(9)		21		(35,901)		241,512
Corporate		1,067,473		(318)		47		(103,333)		963,869
Municipal		633,063		—		194		(106,717)		526,540
Total Fixed Income	$	2,753,631	$	(327)	$	443	$	(301,708)	$	2,452,039
	December 31, 2021
	Cost or		Allowance		Gross		Gross
	Amortized		for Credit		Unrealized		Unrealized		Fair
(in thousands)	Cost		Losses		Gains		Losses		Value
U.S. government	$	127,752	$	—	$	6,846	$	(44)	$	134,554
U.S. agency		30,403		—		2,374		(17)		32,760
Non-U.S. government & agency		8,297		—		338		(154)		8,481
Agency MBS		362,861		—		9,277		(4,951)		367,187
ABS/CMBS/MBS*		264,273		—		2,120		(2,339)		264,054
Corporate		925,394		(441)		37,247		(5,105)		957,095
Municipal		627,287		—		22,750		(4,281)		645,756
Total Fixed Income	$	2,346,267	$	(441)	$	80,952	$	(16,891)	$	2,409,887

* Non-agency asset-backed, commercial mortgage-backed and mortgage-backed securities

Schedule of Debt Securities Available-for-sale Allowance for Credit Loss

	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2022		2021		2022		2021
Beginning balance	$	292	$	204	$	441	$	397
Increase to allowance from securities for which credit losses were not previously recorded		168		—		292		—
Reduction from securities sold during the period		(166)		—		(619)
Reductions from intent to sell securities		—		—		(17)		—
Net increase (decrease) from securities that had an allowance at the beginning of the period		33		22		230		(171)
Balance as of September 30,	$	327	$	226	$	327	$	226

Schedule of Securities in an Unrealized Loss Position Segregated by Type and Length of Time in an Unrealized Loss Position

	September 30, 2022						December 31, 2021
(in thousands)	< 12 Mos.		12 Mos. & Greater		Total		< 12 Mos.		12 Mos. & Greater		Total
U.S. government
Fair value	$	285,302	$	5,315	$	290,617	$	2,942	$	—	$	2,942
Amortized cost		293,829		5,765		299,594		2,986		—		2,986
Unrealized loss	$	(8,527)	$	(450)	$	(8,977)	$	(44)	$	—	$	(44)
U.S. agency
Fair value	$	30,089	$	—	$	30,089	$	1,498	$	—	$	1,498
Amortized cost		32,211		—		32,211		1,515		—		1,515
Unrealized loss	$	(2,122)	$	—	$	(2,122)	$	(17)	$	—	$	(17)
Non-U.S. government
Fair value	$	3,594	$	2,118	$	5,712	$	4,346	$	—	$	4,346
Amortized cost		3,798		3,000		6,798		4,500		—		4,500
Unrealized Loss	$	(204)	$	(882)	$	(1,086)	$	(154)	$	—	$	(154)
Agency MBS
Fair value	$	192,947	$	112,457	$	305,404	$	102,145	$	62,669	$	164,814
Amortized cost		210,448		138,528		348,976		104,336		65,429		169,765
Unrealized loss	$	(17,501)	$	(26,071)	$	(43,572)	$	(2,191)	$	(2,760)	$	(4,951)
ABS/CMBS/MBS*
Fair value	$	148,272	$	89,792	$	238,064	$	150,997	$	3,935	$	154,932
Amortized cost		165,163		108,802		273,965		153,235		4,036		157,271
Unrealized loss	$	(16,891)	$	(19,010)	$	(35,901)	$	(2,238)	$	(101)	$	(2,339)
Corporate
Fair value	$	773,433	$	184,317	$	957,750	$	217,791	$	53,818	$	271,609
Amortized cost		844,169		216,914		1,061,083		221,010		55,704		276,714
Unrealized loss	$	(70,736)	$	(32,597)	$	(103,333)	$	(3,219)	$	(1,886)	$	(5,105)
Municipal
Fair value	$	418,864	$	76,783	$	495,647	$	162,998	$	15,037	$	178,035
Amortized cost		493,485		108,879		602,364		166,602		15,714		182,316
Unrealized loss	$	(74,621)	$	(32,096)	$	(106,717)	$	(3,604)	$	(677)	$	(4,281)
Total fixed income
Fair value	$	1,852,501	$	470,782	$	2,323,283	$	642,717	$	135,459	$	778,176
Amortized cost		2,043,103		581,888		2,624,991		654,184		140,883		795,067
Unrealized loss	$	(190,602)	$	(111,106)	$	(301,708)	$	(11,467)	$	(5,424)	$	(16,891)

* Non-agency asset-backed, commercial mortgage-backed and mortgage-backed securities

Schedule of Credit Quality Indicators for Investments in Unrealized Loss Positions

	Equivalent	Equivalent	(dollars in thousands)
NAIC	S&P	Moody’s	Amortized				Unrealized		Percent
Rating	Rating	Rating	Cost		Fair Value		Loss		to Total
1	AAA/AA/A	Aaa/Aa/A	$	2,084,118	$	1,840,726	$	(243,392)	80.7	%
2	BBB	Baa		399,832		353,124		(46,708)	15.5	%
3	BB	Ba		75,146		67,738		(7,408)	2.5	%
4	B	B		65,238		61,152		(4,086)	1.3	%
5	CCC	Caa		657		543		(114)	0.0	%
6	CC or lower	Ca or lower		—		—		—	0.0	%
		Total	$	2,624,991	$	2,323,283	$	(301,708)	100.0	%