Selective Insurance (SIGI) 10-Q 26 Jul 24 2024 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2024	Jul. 19, 2024
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Document Transition Report	false
Entity File Number	001-33067
Entity Registrant Name	SELECTIVE INSURANCE GROUP, INC
Entity Incorporation, State or Country Code	NJ
Entity Tax Identification Number	22-2168890
Entity Address, Address Line One	40 Wantage Avenue
Entity Address, City or Town	Branchville
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07890
City Area Code	(973)
Local Phone Number	948-3000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		60,833,139
Amendment Flag	false
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Entity Central Index Key	0000230557
Current Fiscal Year End Date	--12-31
Common Stock
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value $2 per share
Trading Symbol	SIGI
Security Exchange Name	NASDAQ
Depositary Shares
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, each representing a 1/1,000th interest in a share of 4.60% Non-Cumulative Preferred Stock, Series B, without par value
Trading Symbol	SIGIP
Security Exchange Name	NASDAQ

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Investments:
Fixed income securities, held-to-maturity – at carrying value (fair value: $18,556 – 2024; $21,923 – 2023)	$ 19,496	$ 22,700
Less: allowance for credit losses	0	0
Fixed income securities, held-to-maturity, net of allowance for credit losses	19,496	22,700
Fixed income securities, available-for-sale – at fair value (allowance for credit losses: $31,309 – 2024 and $28,212 – 2023; amortized cost: $8,080,498 – 2024 and $7,880,697 – 2023)	7,669,033	7,499,197
Commercial mortgage loans – at carrying value (fair value: $209,041 – 2024 and $178,913 – 2023)	219,613	188,708
Less: allowance for credit losses	(154)	(291)
Commercial mortgage loans, net of allowance for credit losses	219,459	188,417
Equity securities – at fair value (cost: $187,286 – 2024; $183,076 – 2023)	191,964	187,155
Short-term investments	417,346	309,317
Alternative investments	414,780	395,779
Other investments	89,742	91,164
Total investments (Note 4 and 5)	9,021,820	8,693,729
Cash	160	180
Restricted cash	10,748	13,092
Accrued investment income	72,305	66,339
Premiums receivable	1,600,765	1,331,979
Less: allowance for credit losses (Note 6)	(21,100)	(18,900)
Premiums receivable, net of allowance for credit losses	1,579,665	1,313,079
Reinsurance recoverable	687,288	658,525
Less: allowance for credit losses (Note 7)	(1,700)	(1,700)
Reinsurance recoverable, net of allowance for credit losses	685,588	656,825
Prepaid reinsurance premiums	219,785	203,320
Current federal income tax	38,588	0
Deferred federal income tax	145,897	140,237
Property and equipment – at cost, net of accumulated depreciation and amortization of: $278,525 – 2024; $271,409 – 2023	89,196	83,272
Deferred policy acquisition costs	476,519	424,864
Goodwill	7,849	7,849
Other assets	217,370	199,760
Total assets	12,565,490	11,802,546
Liabilities:
Reserve for loss and loss expense (Note 8)	5,903,525	5,336,911
Unearned premiums	2,598,668	2,330,656
Long-term debt	508,801	503,946
Current federal income tax	0	6,251
Accrued salaries and benefits	92,585	122,003
Other liabilities	539,220	548,398
Total liabilities	9,642,799	8,848,165
Stockholders’ Equity:
Preferred stock of $0 par value per share: Authorized shares 5,000,000; Issued shares: 8,000 with $25,000 liquidation preference per share - 2024 and 2023	200,000	200,000
Common stock of $2 par value per share: Authorized shares 360,000,000 Issued: 105,516,194 – 2024; 105,223,307 – 2023	211,032	210,447
Additional paid-in capital	545,263	522,748
Retained earnings	3,001,054	3,029,396
Accumulated other comprehensive income (loss) (Note 11)	(392,721)	(373,001)
Treasury stock – at cost (shares:  44,656,246 – 2024; 44,586,870 – 2023)	(641,937)	(635,209)
Total stockholders’ equity	2,922,691	2,954,381
Commitments and contingencies
Total liabilities and stockholders’ equity	$ 12,565,490	$ 11,802,546

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Fixed income securities, held-to-maturity, fair value	$ 18,556	$ 21,923
Fixed income securities, available-for-sale, allowance for credit loss	31,309	28,212
Fixed income securities, available-for-sale, amortized cost	8,080,498	7,880,697
Commercial mortgage loans, fair value	209,041	178,913
Equity securities, cost	187,286	183,076
Property and equipment, accumulated depreciation and amortization	$ 278,525	$ 271,409
Preferred stock, par or stated value (in dollars per share)	$ 0	$ 0
Preferred stock, authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	8,000	8,000
Preferred stock, liquidation preference (in dollars per share)	$ 25,000	$ 25,000
Common stock, par or stated value (in dollars per share)	$ 2	$ 2
Common stock, authorized (in shares)	360,000,000	360,000,000
Common stock, issued (in shares)	105,516,194	105,223,307
Treasury stock, common (in shares)	44,656,246	44,586,870

Unaudited Consolidated Statemen

Unaudited Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenues:
Net premiums earned	$ 1,080,231	$ 942,150	$ 2,131,175	$ 1,844,486
Net investment income earned	108,642	97,696	216,491	189,202
Net realized and unrealized investment gains (losses)	1,297	(5,426)	(338)	(2,082)
Other income	5,835	6,104	13,636	8,738
Total revenues	1,196,005	1,040,524	2,360,964	2,040,344
Expenses:
Loss and loss expense incurred	925,548	646,130	1,629,840	1,213,568
Amortization of deferred policy acquisition costs	226,426	194,793	445,861	384,554
Other insurance expenses	107,773	108,857	223,760	217,445
Interest expense	7,202	7,258	14,383	14,424
Corporate expenses	9,154	9,329	24,652	21,437
Total expenses	1,276,103	966,367	2,338,496	1,851,428
Income (loss) before federal income tax	(80,098)	74,157	22,468	188,916
Federal income tax expense (benefit):
Current	(17,622)	17,366	3,791	42,871
Deferred	843	(1,817)	(522)	(5,137)
Total federal income tax expense (benefit)	(16,779)	15,549	3,269	37,734
Net income (loss)	(63,319)	58,608	19,199	151,182
Preferred stock dividends	2,300	2,300	4,600	4,600
Net income (loss) available to common stockholders	$ (65,619)	$ 56,308	$ 14,599	$ 146,582
Earnings per common share:
Net income (loss) available to common stockholders - Basic (in dollars per share)	$ (1.08)	$ 0.93	$ 0.24	$ 2.42
Net income (loss) available to common stockholders - Diluted (in dollars per share)	$ (1.08)	$ 0.92	$ 0.24	$ 2.41

Unaudited Consolidated Statem_2

Unaudited Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (63,319)	$ 58,608	$ 19,199	$ 151,182
Unrealized gains (losses) on investment securities:
Unrealized holding gains (losses) arising during period	(6,594)	(47,937)	(18,887)	4,142
Unrealized gains (losses) on securities with credit loss recognized in earnings	(2,927)	(4,764)	(5,401)	12,957
Amounts reclassified into net income (loss):
Net realized (gains) losses on disposals and losses on intent-to-sell available-for-sale securities	33	7,413	(28)	12,235
Credit loss (benefit) expense	975	(683)	3,068	(8,210)
Total unrealized gains (losses) on investment securities	(8,513)	(45,971)	(21,248)	21,124
Defined benefit pension and post-retirement plans:
Amounts reclassified into net income (loss): Net actuarial loss	764	598	1,528	1,196
Total defined benefit pension and post-retirement plans	764	598	1,528	1,196
Other comprehensive income (loss)	(7,749)	(45,373)	(19,720)	22,320
Comprehensive income (loss)	$ (71,068)	$ 13,235	$ (521)	$ 173,502

Unaudited Consolidated Statem_3

Unaudited Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred stock:	Common stock:	Additional paid-in capital:	Retained earnings:	Accumulated other comprehensive income (loss):	Treasury stock:
Beginning of period at Dec. 31, 2022		$ 200,000	$ 209,694	$ 493,488	$ 2,749,703	$ (498,042)	$ (627,279)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock		0
Dividend reinvestment plan			19	908
Stock purchase and compensation plans			583	17,644
Net income (loss)	$ 151,182				151,182
Dividends to preferred stockholders					(4,600)
Dividends to common stockholders					(36,716)
Other comprehensive income (loss)	22,320					22,320
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans							(7,512)
End of period at Jun. 30, 2023	$ 2,671,392	$ 200,000	210,296	512,040	2,859,569	(475,722)	(634,791)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per preferred share (in dollars per share)	$ 575
Dividends declared per common share (in dollars per share)	$ 0.60
Preferred stock, shares outstanding, beginning balance (in shares) at Dec. 31, 2022	8,000
Preferred stock, shares outstanding:
Issuance of preferred stock (in shares)		0
Preferred stock, shares outstanding, ending balance (in shares) at Jun. 30, 2023	8,000
Common stock, shares outstanding, beginning of period (in shares) at Dec. 31, 2022	60,338,900
Common stock, shares outstanding:
Dividend reinvestment plan (in shares)	9,315
Stock purchase and compensation plan (in shares)	291,739
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans (in shares)	(74,471)
Common stock, shares outstanding, end of period (in shares) at Jun. 30, 2023	60,565,483
Beginning of period at Mar. 31, 2023		$ 200,000	210,149	502,713	2,821,613	(430,349)	(634,722)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock		0
Dividend reinvestment plan			10	449
Stock purchase and compensation plans			137	8,878
Net income (loss)	$ 58,608				58,608
Dividends to preferred stockholders					(2,300)
Dividends to common stockholders					(18,352)
Other comprehensive income (loss)	(45,373)					(45,373)
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans							(69)
End of period at Jun. 30, 2023	$ 2,671,392	$ 200,000	210,296	512,040	2,859,569	(475,722)	(634,791)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per preferred share (in dollars per share)	$ 287.50
Dividends declared per common share (in dollars per share)	$ 0.30
Preferred stock, shares outstanding, beginning balance (in shares) at Mar. 31, 2023	8,000
Preferred stock, shares outstanding:
Issuance of preferred stock (in shares)		0
Preferred stock, shares outstanding, ending balance (in shares) at Jun. 30, 2023	8,000
Common stock, shares outstanding, beginning of period (in shares) at Mar. 31, 2023	60,492,586
Common stock, shares outstanding:
Dividend reinvestment plan (in shares)	4,665
Stock purchase and compensation plan (in shares)	68,923
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans (in shares)	(691)
Common stock, shares outstanding, end of period (in shares) at Jun. 30, 2023	60,565,483
Beginning of period at Dec. 31, 2023	$ 2,954,381	$ 200,000	210,447	522,748	3,029,396	(373,001)	(635,209)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock		0
Dividend reinvestment plan			20	972
Stock purchase and compensation plans			565	21,543
Net income (loss)	19,199				19,199
Dividends to preferred stockholders					(4,600)
Dividends to common stockholders					(42,941)
Other comprehensive income (loss)	(19,720)					(19,720)
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans							(6,728)
End of period at Jun. 30, 2024	$ 2,922,691	$ 200,000	211,032	545,263	3,001,054	(392,721)	(641,937)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per preferred share (in dollars per share)	$ 575
Dividends declared per common share (in dollars per share)	$ 0.70
Preferred stock, shares outstanding, beginning balance (in shares) at Dec. 31, 2023	8,000
Preferred stock, shares outstanding:
Issuance of preferred stock (in shares)		0
Preferred stock, shares outstanding, ending balance (in shares) at Jun. 30, 2024	8,000
Common stock, shares outstanding, beginning of period (in shares) at Dec. 31, 2023	60,636,437
Common stock, shares outstanding:
Dividend reinvestment plan (in shares)	9,959
Stock purchase and compensation plan (in shares)	282,928
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans (in shares)	(69,376)
Common stock, shares outstanding, end of period (in shares) at Jun. 30, 2024	60,859,948
Beginning of period at Mar. 31, 2024		$ 200,000	210,895	534,327	3,088,150	(384,972)	(641,906)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock		0
Dividend reinvestment plan			10	484
Stock purchase and compensation plans			127	10,452
Net income (loss)	$ (63,319)				(63,319)
Dividends to preferred stockholders					(2,300)
Dividends to common stockholders					(21,477)
Other comprehensive income (loss)	(7,749)					(7,749)
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans							(31)
End of period at Jun. 30, 2024	$ 2,922,691	$ 200,000	$ 211,032	$ 545,263	$ 3,001,054	$ (392,721)	$ (641,937)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per preferred share (in dollars per share)	$ 287.50
Dividends declared per common share (in dollars per share)	$ 0.35
Preferred stock, shares outstanding, beginning balance (in shares) at Mar. 31, 2024	8,000
Preferred stock, shares outstanding:
Issuance of preferred stock (in shares)		0
Preferred stock, shares outstanding, ending balance (in shares) at Jun. 30, 2024	8,000
Common stock, shares outstanding, beginning of period (in shares) at Mar. 31, 2024	60,791,439
Common stock, shares outstanding:
Dividend reinvestment plan (in shares)	5,153
Stock purchase and compensation plan (in shares)	63,664
Acquisition of treasury stock - shares acquired related to employee share-based compensation plans (in shares)	(308)
Common stock, shares outstanding, end of period (in shares) at Jun. 30, 2024	60,859,948

Unaudited Consolidated Statem_4

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Operating Activities
Net income (loss)	$ 19,199	$ 151,182
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	18,915	17,179
Stock-based compensation expense	16,709	12,886
Undistributed gains of equity method investments	(14,572)	(13,478)
Distributions in excess of current year income of equity method investments	10,377	6,698
Net realized and unrealized (gains) losses	338	2,082
Loss (gain) on disposal of fixed assets	321	5
Changes in assets and liabilities:
Increase in reserve for loss and loss expense, net of reinsurance recoverable	537,851	168,221
Increase in unearned premiums, net of prepaid reinsurance	251,547	240,189
(Increase) decrease in net federal income taxes	(45,257)	1,006
Increase in premiums receivable	(266,586)	(200,807)
Increase in deferred policy acquisition costs	(51,655)	(45,189)
Increase in accrued investment income	(5,926)	(264)
Decrease in accrued salaries and benefits	(29,418)	(23,192)
Increase in other assets	(22,122)	(4,667)
Decrease in other liabilities	(39,385)	(18,205)
Net cash provided by (used in) operating activities	380,336	293,646
Investing Activities
Purchases of fixed income securities, available-for-sale	(1,027,136)	(1,562,206)
Purchases of commercial mortgage loans	(34,281)	(27,201)
Purchases of equity securities	(13,738)	(8,373)
Purchases of alternative investments and other investments	(34,000)	(21,161)
Purchases of short-term investments	(3,016,380)	(2,422,123)
Sales of fixed income securities, available-for-sale	451,386	959,248
Proceeds from commercial mortgage loans	3,376	968
Sales of short-term investments	2,908,653	2,543,683
Redemption and maturities of fixed income securities, held-to-maturity	3,204	7,481
Redemption and maturities of fixed income securities, available-for-sale	415,790	227,884
Sales of equity securities	12,252	51,763
Sales of other investments	0	892
Distributions from alternative investments and other investments	11,526	5,130
Purchases of property and equipment	(13,932)	(9,549)
Net cash provided by (used in) investing activities	(333,280)	(253,564)
Financing Activities
Dividends to preferred stockholders	(4,600)	(4,600)
Dividends to common stockholders	(41,573)	(35,385)
Acquisition of treasury stock	(6,728)	(7,512)
Net proceeds from stock purchase and compensation plans	4,747	4,695
Proceeds from borrowings	0	20,000
Repayments of borrowings	0	(20,000)
Repayments of finance lease obligations	(1,266)	(1,231)
Net cash provided by (used in) financing activities	(49,420)	(44,033)
Net increase (decrease) in cash and restricted cash	(2,364)	(3,951)
Cash and restricted cash, beginning of period	13,272	25,209
Cash and restricted cash, end of period	$ 10,908	$ 21,258

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The words "Company,” “we,” “us,” or “our” refer to Selective Insurance Group, Inc. (the "Parent") and its subsidiaries, except as expressly indicated or the context requires otherwise. We have prepared our interim unaudited consolidated financial statements (“Financial Statements”) in conformity with (i) United States ("U.S.") generally accepted accounting principles (“GAAP”), and (ii) the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. These require management to make estimates and assumptions that affect the reported financial statement balances and the disclosure of contingent assets and liabilities. Actual results could differ from those estimates. All significant intercompany accounts and transactions are eliminated in consolidation.

Adoption of Accounting Pronounc

Adoption of Accounting Pronouncements	6 Months Ended
	Jun. 30, 2024
Accounting Policies [Abstract]
Adoption of Accounting Pronouncements	Adoption of Accounting Pronouncements In June 2022, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2022-03, Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions (“ASU 2022-03”). ASU 2022-03 clarifies that a contractual sales restriction on an equity security is not considered when determining the security's fair value. This ASU was issued to eliminate diversity in practice by clarifying that contractual arrangements restricting an entity's ability to sell the security for a certain period of time is a characteristic of the reporting entity and should not be contemplated when determining the security's fair value. ASU 2022-03 requires new disclosures that provide investors with information about the restriction, including the nature and remaining duration of the restriction. The ASU is effective for annual periods beginning after December 15, 2023, including interim periods within those annual periods. We adopted this guidance on January 1, 2024 and it did not have a material impact to our financial condition, results of operations, or disclosures. In March 2023, the FASB issued ASU 2023-02, Investments — Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method ("ASU 2023-02"). This ASU allows companies to elect to account for qualifying tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. Companies were previously permitted to apply the proportional amortization method only to qualifying tax equity investments in low income housing tax credit structures. ASU 2023-02 extends the application of the proportional amortization method to qualifying tax equity investments that generate tax credits through other programs. It also requires new disclosures that provide a better understanding of the nature of the tax equity investments and the effect the tax equity investments and related income tax credits and other income tax benefits have on a company's financial position and results of operations. The ASU is effective for annual periods beginning after December 15, 2023, including interim periods within those fiscal years. We adopted ASU 2023-02 on January 1, 2024 and it did not have a material impact to our financial condition, results of operations, or disclosures. Pronouncements to be effective in the future In November 2023, the FASB issued ASU 2023-07, Improvements to Reportable Segment Disclosures ("ASU 2023-07"). ASU 2023-07 amends disclosure requirements for segment reporting by modifying and adding disclosure requirements. The additional disclosure requirements include the following on both an interim and annual basis: (i) significant segment expenses that are regularly provided to the chief operating decision maker ("CODM"); (ii) amounts for "other segment items" by reportable segment and a description of its composition; and (iii) the title and position of the CODM and an explanation of how the CODM uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. In addition, ASU 2023-07 requires all annual disclosures about a reportable segment’s profit or loss and assets currently required by Topic 280, Segment Reporting , to now be disclosed in interim periods. ASU 2023-07 is effective for annual periods beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. As it only requires additional disclosure, ASU 2023-07 will not have a material impact on our financial condition or results of operations. In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 amends disclosure requirements to provide greater transparency on income taxes. The following additional disclosures are required annually: (i) specific required categories in the rate reconciliation, (ii) additional information for reconciling items that meet a quantitative threshold, (iii) the amount of income taxes paid disaggregated by jurisdiction, and (iv) income tax expense (or benefit) from continuing operations disaggregated by federal, state, and foreign. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Amendments can be applied on a prospective basis; however, retrospective application is permitted. Early adoption is permitted. As it only requires additional disclosure, ASU 2023-09 will not have a material impact on our financial condition or results of operations.

Statements of Cash Flows

Statements of Cash Flows	6 Months Ended
	Jun. 30, 2024
Supplemental Cash Flow Information [Abstract]
Statements of Cash Flows	Statements of Cash Flows Supplemental cash flow information was as follows: Six Months ended June 30, ($ in thousands) 2024 2023 Cash paid (received) during the period for: Interest $ 14,209 14,164 Federal income tax 46,000 34,000 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases 3,884 4,038 Operating cash flows from financing leases 65 20 Financing cash flows from finance leases 1,266 1,231 Non-cash items: Corporate actions related to fixed income securities, available-for-sale ("AFS") 1 10,250 23,150 Corporate actions related to equity securities 1 29,250 — Assets acquired under finance lease arrangements 5,947 — Assets acquired under operating lease arrangements 10,257 4,509 Non-cash purchase of property and equipment 9 — 1 Examples of corporate actions include like-kind exchanges, non-cash acquisitions, and stock splits. The following table provides a reconciliation of cash and restricted cash reported within the Consolidated Balance Sheets that equate to the amount reported in the Consolidated Statements of Cash Flows: ($ in thousands) June 30, 2024 December 31, 2023 Cash $ 160 180 Restricted cash 10,748 13,092 Total cash and restricted cash shown in the Consolidated Statements of Cash Flows $ 10,908 13,272 Amounts in restricted cash represent cash received from the National Flood Insurance Program ("NFIP") that can only be used to pay flood claims under the Write Your Own program.

Investments

Investments	6 Months Ended
	Jun. 30, 2024
Investments [Abstract]
Investments	Investments (a) Information regarding our AFS securities as of June 30, 2024 and December 31, 2023, were as follows: June 30, 2024 Cost/ Allowance for Credit Losses Unrealized Unrealized Fair ($ in thousands) AFS fixed income securities: U.S. government and government agencies $ 170,819 — 56 (19,907) 150,968 Foreign government 10,687 (26) — (1,427) 9,234 Obligations of states and political subdivisions 558,455 (639) 770 (33,151) 525,435 Corporate securities 2,987,824 (15,950) 17,803 (143,725) 2,845,952 Collateralized loan obligations ("CLO") and other asset-backed securities ("ABS") 1,972,687 (3,022) 16,359 (69,904) 1,916,120 Residential mortgage-backed securities ("RMBS") 1,624,078 (11,660) 2,954 (111,420) 1,503,952 Commercial mortgage-backed securities ("CMBS") 755,948 (12) 814 (39,378) 717,372 Total AFS fixed income securities $ 8,080,498 (31,309) 38,756 (418,912) 7,669,033 December 31, 2023 Cost/ Allowance for Credit Losses Unrealized Unrealized Fair ($ in thousands) AFS fixed income securities: U.S. government and government agencies $ 223,157 — 139 (18,261) 205,035 Foreign government 11,140 (35) — (1,302) 9,803 Obligations of states and political subdivisions 612,938 (669) 2,623 (28,927) 585,965 Corporate securities 2,834,048 (12,999) 28,078 (137,888) 2,711,239 CLO and other ABS 1,911,831 (2,854) 11,855 (86,005) 1,834,827 RMBS 1,568,960 (11,649) 6,023 (85,851) 1,477,483 CMBS 718,623 (6) 1,358 (45,130) 674,845 Total AFS fixed income securities $ 7,880,697 (28,212) 50,076 (403,364) 7,499,197 The following tables provide a roll forward of the allowance for credit losses on our AFS fixed income securities for the indicated periods: Quarter ended June 30, 2024 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 29 — — (3) — — 26 Obligations of states and political subdivisions 695 18 — (74) — — 639 Corporate securities 15,442 846 — (126) (212) — 15,950 CLO and other ABS 2,627 271 — 126 (2) — 3,022 RMBS 11,580 — — 171 (91) — 11,660 CMBS 8 — — 4 — — 12 Total AFS fixed income securities $ 30,381 1,135 — 98 (305) — 31,309 Quarter ended June 30, 2023 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 36 — — (2) — — 34 Obligations of states and political subdivisions 737 67 — (35) — — 769 Corporate securities 16,756 1,438 — (1,070) (939) (36) 16,149 CLO and other ABS 3,895 622 — (1,595) (7) — 2,915 RMBS 11,740 1 — (50) (141) — 11,550 CMBS 390 — — (240) (142) — 8 Total AFS fixed income securities $ 33,554 2,128 — (2,992) (1,229) (36) 31,425 Six Months ended June 30, 2024 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 35 — — (3) (6) — 26 Obligations of states and political subdivisions 669 37 — (59) (8) — 639 Corporate securities 12,999 2,362 — 1,166 (568) (9) 15,950 CLO and other ABS 2,854 427 — (255) (4) — 3,022 RMBS 11,649 — — 202 (191) — 11,660 CMBS 6 2 — 4 — — 12 Total AFS fixed income securities $ 28,212 2,828 — 1,055 (777) (9) 31,309 Six Months ended June 30, 2023 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 284 — — (250) — — 34 Obligations of states and political subdivisions 1,024 67 — (239) (83) — 769 Corporate securities 30,330 4,141 — (14,884) (3,387) (51) 16,149 CLO and other ABS 2,375 677 — (127) (10) — 2,915 RMBS 11,597 8 — 174 (229) — 11,550 CMBS 111 1 — 39 (143) — 8 Total AFS fixed income securities $ 45,721 4,894 — (15,287) (3,852) (51) 31,425 During Six Months 2024 and Six Months 2023, we had no write-offs or recoveries of our AFS fixed income securities. For information on our methodology and significant inputs used to measure expected credit losses, our accounting policy for recognizing write-offs of uncollectible amounts, and our treatment of accrued interest, refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2023 Annual Report. Accrued interest on AFS securities was $70.1 million as of June 30, 2024, and $64.6 million as of December 31, 2023. We did not record any write-offs of accrued interest in Six Months 2024 and Six Months 2023. (b) Quantitative information about unrealized losses on our AFS portfolio follows: June 30, 2024 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized AFS fixed income securities: U.S. government and government agencies $ 33,667 (52) 107,306 (19,855) 140,973 (19,907) Foreign government — — 9,234 (1,427) 9,234 (1,427) Obligations of states and political subdivisions 128,665 (1,644) 329,528 (31,507) 458,193 (33,151) Corporate securities 358,779 (3,477) 1,477,738 (140,248) 1,836,517 (143,725) CLO and other ABS 368,307 (6,432) 798,783 (63,472) 1,167,090 (69,904) RMBS 385,794 (6,133) 878,915 (105,287) 1,264,709 (111,420) CMBS 75,052 (779) 550,901 (38,599) 625,953 (39,378) Total AFS fixed income securities $ 1,350,264 (18,517) 4,152,405 (400,395) 5,502,669 (418,912) December 31, 2023 Less than 12 months 12 months or longer Total ($ in thousands) Fair Unrealized Fair Value Unrealized Fair Value Unrealized AFS fixed income securities: U.S. government and government agencies $ 77,698 (188) 108,578 (18,073) 186,276 (18,261) Foreign government 1,552 (87) 8,251 (1,215) 9,803 (1,302) Obligations of states and political subdivisions 137,031 (962) 290,964 (27,965) 427,995 (28,927) Corporate securities 263,423 (6,369) 1,439,422 (131,519) 1,702,845 (137,888) CLO and other ABS 278,940 (7,120) 984,175 (78,885) 1,263,115 (86,005) RMBS 351,976 (4,765) 757,914 (81,086) 1,109,890 (85,851) CMBS 130,189 (2,995) 471,256 (42,135) 601,445 (45,130) Total AFS fixed income securities $ 1,240,809 (22,486) 4,060,560 (380,878) 5,301,369 (403,364) We currently do not intend to sell any of the securities summarized in the tables above, nor do we believe we will be required to sell any of them. Considering these factors and our review of these securities under our credit loss policy as described in Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2023 Annual Report, we have concluded that no additional allowance for credit loss is required on these balances beyond the allowance for credit loss recorded as of June 30, 2024. This conclusion reflects our current judgment about the financial position and future prospects of the entities that issued the investment security and underlying collateral. (c) AFS and held-to-maturity ("HTM") fixed income securities at June 30, 2024, by contractual maturity are shown below. The maturities of RMBS, CMBS, CLO and other ABS securities were calculated using each security's estimated average life. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. AFS HTM ($ in thousands) Fair Value Carrying Value Fair Value Due in one year or less $ 587,352 820 810 Due after one year through five years 3,507,774 14,209 13,662 Due after five years through 10 years 2,827,999 4,467 4,084 Due after 10 years 745,908 — — Total fixed income securities $ 7,669,033 19,496 18,556 (d) The following table summarizes our alternative investment portfolio by strategy: June 30, 2024 December 31, 2023 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss Carrying Value Remaining Commitment Maximum Exposure to Loss Alternative Investments Private equity $ 319,236 148,558 467,794 301,759 131,885 433,644 Private credit 52,106 98,417 150,523 54,500 89,401 143,901 Real assets 43,438 42,336 85,774 39,520 33,040 72,560 Total alternative investments $ 414,780 289,311 704,091 395,779 254,326 650,105 We are contractually committed to make additional investments up to the remaining commitments stated above. We did not provide any non-contractual financial support during 2024 or 2023. The following table shows gross summarized financial information for our alternative investments portfolio, including the portion we do not own. As the majority of these investments report results to us on a one quarter lag, the summarized financial statement information is for 3- and 6-month periods ended March 31: Income Statement Information Quarter ended June 30, Six Months ended June 30, ($ in millions) 2024 2023 2024 2023 Net investment income (loss) $ 242.4 (70.6) $ (103.6) (141.3) Realized gains 1,554.2 922.0 3,385.1 2,644.3 Net change in unrealized appreciation (depreciation) 2,850.2 3,754.0 6,669.2 5,197.8 Net income $ 4,646.8 4,605.4 $ 9,950.7 7,700.8 Alternative investment income included in "Net investment income earned" on our Consolidated Statements of Income $ 10.5 11.4 $ 17.4 19.2 (e) We have pledged certain AFS fixed income securities as collateral related to our borrowing relationships with the Federal Home Loan Bank of Indianapolis ("FHLBI") and the Federal Home Loan Bank of New York ("FHLBNY"). In addition, we had certain securities on deposit with various state and regulatory agencies at June 30, 2024 to comply with insurance laws. We retain all rights regarding all securities pledged as collateral. The following table summarizes the market value of these securities at June 30, 2024: ($ in millions) FHLBI Collateral FHLBNY Collateral State and Total U.S. government and government agencies $ — — 19.9 19.9 Obligations of states and political subdivisions — — 4.2 4.2 RMBS 64.2 23.2 — 87.4 CMBS 2.1 8.3 — 10.4 Total pledged as collateral $ 66.3 31.5 24.1 121.9 (f) We did not have exposure to any credit concentration risk of a single issuer greater than 10% of our stockholders' equity, other than to certain U.S. government agencies, as of June 30, 2024, or December 31, 2023. (g) The components of pre-tax net investment income earned were as follows: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Fixed income securities $ 93,935 83,916 $ 188,037 164,003 Commercial mortgage loans ("CMLs") 3,145 2,199 5,939 4,164 Equity securities 1,877 2,236 6,785 3,441 Short-term investments 4,680 2,892 8,199 7,542 Alternative investments 10,517 11,396 17,398 19,164 Other investments 118 188 381 231 Investment expenses (5,630) (5,131) (10,248) (9,343) Net investment income earned $ 108,642 97,696 $ 216,491 189,202 The increase in net investment income earned in Second Quarter 2024 and Six Months 2024 compared to the same prior-year periods was primarily driven by higher interest rates, active portfolio management, and operating and investing cash flow deployment. (h) The following table summarizes net realized and unrealized investment gains and losses for the periods indicated: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Gross gains on sales $ 4,387 1,156 $ 6,522 4,940 Gross losses on sales (1,251) (11,952) (3,216) (24,882) Net realized gains (losses) on disposals 3,136 (10,796) 3,306 (19,942) Net unrealized gains (losses) on equity securities (93) 4,925 599 8,173 Net credit loss benefit (expense) on fixed income securities, AFS (1,233) 864 (3,883) 10,393 Net credit loss benefit (expense) on CMLs (32) (78) 136 (61) Losses on securities for which we have the intent to sell (481) (341) (496) (645) Net realized and unrealized investment gains (losses) $ 1,297 (5,426) $ (338) (2,082) Net unrealized gains and losses recognized in income on equity securities, as reflected in the table above, included the following: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Unrealized gains (losses) recognized in income on equity securities: On securities remaining in our portfolio at end of period $ 2,617 2,784 $ 2,906 2,685 On securities sold in period (2,710) 2,141 (2,307) 5,488 Total unrealized gains (losses) recognized in income on equity securities $ (93) 4,925 $ 599 8,173

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The financial assets in our investment portfolio are primarily measured at fair value as disclosed on the Consolidated Balance Sheets. The following table presents the carrying amounts and fair values of our financial liabilities as of June 30, 2024, and December 31, 2023: June 30, 2024 December 31, 2023 ($ in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial Liabilities Long-term debt: 7.25% Senior Notes $ 49,928 51,301 49,926 53,047 6.70% Senior Notes 99,577 99,393 99,565 104,039 5.375% Senior Notes 294,574 283,037 294,523 288,787 3.03% borrowings from FHLBI 60,000 57,638 60,000 57,932 Subtotal long-term debt 504,079 491,369 504,014 503,805 Unamortized debt issuance costs (2,596) (2,704) Finance lease obligations 7,318 2,636 Total long-term debt $ 508,801 503,946 For discussion regarding the fair value techniques of our financial instruments, refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2023 Annual Report. The following tables provide quantitative disclosures of our financial assets that were measured and recorded at fair value at June 30, 2024, and December 31, 2023: June 30, 2024 Fair Value Measurements Using ($ in thousands) Assets Quoted Prices in Significant Other Significant Unobservable Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 150,968 33,453 117,515 — Foreign government 9,234 — 9,234 — Obligations of states and political subdivisions 525,435 — 517,781 7,654 Corporate securities 2,845,952 — 2,552,239 293,713 CLO and other ABS 1,916,120 — 1,652,400 263,720 RMBS 1,503,952 — 1,499,066 4,886 CMBS 717,372 — 717,023 349 Total AFS fixed income securities 7,669,033 33,453 7,065,258 570,322 Equity securities: Common stock 1 190,141 34,815 — 1,067 Preferred stock 1,823 1,823 — — Total equity securities 191,964 36,638 — 1,067 Short-term investments 417,346 400,906 16,440 — Total assets measured at fair value $ 8,278,343 470,997 7,081,698 571,389 December 31, 2023 Fair Value Measurements Using ($ in thousands) Assets Quoted Prices in Significant Significant Unobservable Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 205,035 34,056 170,979 — Foreign government 9,803 — 9,803 — Obligations of states and political subdivisions 585,965 — 578,131 7,834 Corporate securities 2,711,239 — 2,413,907 297,332 CLO and other ABS 1,834,827 — 1,589,514 245,313 RMBS 1,477,483 — 1,477,483 — CMBS 674,845 — 674,489 356 Total AFS fixed income securities 7,499,197 34,056 6,914,306 550,835 Equity securities: Common stock 1 185,339 20,582 — 854 Preferred stock 1,816 1,816 — — Total equity securities 187,155 22,398 — 854 Short-term investments 309,317 308,512 805 — Total assets measured at fair value $ 7,995,669 364,966 6,915,111 551,689 1 Investments amounting to $154.3 million at June 30, 2024, and $163.9 million at December 31, 2023, were measured at fair value using the net asset value per share (or its practical expedient) and have not been classified in the fair value hierarchy. These investments are not redeemable and the timing of liquidations of the underlying assets is unknown at each reporting period. The fair value amounts in this table are intended to permit reconciliation of the fair value hierarchy to total assets measured at fair value. The following tables provide a summary of Level 3 changes in Six Months 2024 and Six Months 2023: June 30, 2024 ($ in thousands) Obligations of States and Political Subdivisions Corporate Securities CLO and Other ABS RMBS CMBS Common Stock Total Fair value, December 31, 2023 $ 7,834 297,332 245,313 — 356 854 551,689 Total net gains (losses) for the period included in: Other comprehensive income (loss) ("OCI") (112) 1,203 969 — (2) — 2,058 Net realized and unrealized gains (losses) — 218 39 — — 213 470 Net investment income earned — (494) (7) — (1) — (502) Purchases — 5,261 30,119 4,886 — — 40,266 Sales — — — — — — — Issuances — — — — — — — Settlements (68) (7,269) (4,726) — (4) — (12,067) Transfers into Level 3 — 28,896 19,537 — — — 48,433 Transfers out of Level 3 — (31,434) (27,524) — — — (58,958) Fair value, June 30, 2024 $ 7,654 293,713 263,720 4,886 349 1,067 571,389 Change in unrealized gains (losses) for the period included in earnings for assets held at period end — 226 39 — — 213 478 Change in unrealized gains (losses) for the period included in OCI for assets held at period end (112) 850 969 — (2) — 1,705 June 30, 2023 ($ in thousands) Obligation of state and Political Subdivisions Corporate Securities CLO and Other ABS CMBS Common Stock Total Fair value, December 31, 2022 $ 6,661 187,980 153,342 375 897 349,255 Total net gains (losses) for the period included in: OCI (7) 1,857 (1,168) 64 — 746 Net realized and unrealized gains (losses) 62 251 17 — (235) 95 Net investment income earned — 112 (20) (263) — (171) Purchases — 58,586 39,713 — — 98,299 Sales — — — — — — Issuances — — — — — — Settlements — (5,535) (3,153) (21) — (8,709) Transfers into Level 3 — 2,238 14,148 2,848 — 19,234 Transfers out of Level 3 — — (953) (2,626) — (3,579) Fair value, June 30, 2023 $ 6,716 245,489 201,926 377 662 455,170 Change in unrealized gains (losses) for the period included in earnings for assets held at period end 62 251 17 — (235) 95 Change in unrealized gains (losses) for the period included in OCI for assets held at period end (7) 1,846 (1,168) 64 — 735 The following tables present quantitative information about the significant unobservable inputs used in the fair value measurements of Level 3 assets at June 30, 2024, and December 31, 2023: June 30, 2024 ($ in thousands) Assets Measured at Fair Value Valuation Techniques Unobservable Inputs Range Weighted Average Internal valuations: Corporate securities $ 154,075 Discounted Cash Flow Illiquidity Spread (4.4)% - 5.3% 1.8% CLO and other ABS 158,660 Discounted Cash Flow Illiquidity Spread 0.01% - 19.6% 2.5% Total internal valuations 312,735 Other 1 258,654 Total Level 3 securities $ 571,389 December 31, 2023 ($ in thousands) Assets Measured at Fair Value Valuation Techniques Unobservable Inputs Range Weighted Average Internal valuations: Corporate securities $ 135,524 Discounted Cash Flow Illiquidity Spread (4.4)% - 5.3% 1.9% CLO and other ABS 127,210 Discounted Cash Flow Illiquidity Spread 0.01% - 19.6% 2.4% Total internal valuations 262,734 Other 1 288,955 Total Level 3 securities $ 551,689 1 Other is comprised of broker quotes or other third-party pricing for which there is a lack of transparency into the inputs used to develop the valuations. The quantitative details of these unobservable inputs are neither provided to us, nor reasonably available to us, and therefore are not included in the tables above. For the securities in the tables above valued using a discounted cash flow analysis, we apply an illiquidity spread in our determination of fair value. An increase in this assumption would result in a lower fair value measurement. The following tables provide quantitative information about our financial assets and liabilities that were not measured at fair value, but were disclosed as such at June 30, 2024, and December 31, 2023: June 30, 2024 Fair Value Measurements Using ($ in thousands) Assets/ Quoted Prices in Significant Other Significant Financial Assets HTM: Corporate securities $ 18,556 — 18,556 — Total HTM fixed income securities 18,556 — 18,556 — CMLs $ 209,041 — — 209,041 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 51,301 — 51,301 — 6.70% Senior Notes 99,393 — 99,393 — 5.375% Senior Notes 283,037 — 283,037 — 3.03% borrowings from FHLBI 57,638 — 57,638 — Total long-term debt $ 491,369 — 491,369 — December 31, 2023 Fair Value Measurements Using ($ in thousands) Assets/ Quoted Prices in Significant Other Significant Financial Assets HTM: Corporate securities $ 21,923 — 21,923 — Total HTM fixed income securities 21,923 — 21,923 — CMLs $ 178,913 — — 178,913 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 53,047 — 53,047 — 6.70% Senior Notes 104,039 — 104,039 — 5.375% Senior Notes 288,787 — 288,787 — 3.03% borrowings from FHLBI 57,932 — 57,932 — Total long-term debt $ 503,805 — 503,805 —

Allowance for Credit Losses on

Allowance for Credit Losses on Premiums Receivable	6 Months Ended
	Jun. 30, 2024
Premiums Receivable Disclosure [Abstract]
Allowance for Credit Losses on Premiums Receivable	Allowance for Credit Losses on Premiums Receivable The following table provides a roll forward of the allowance for credit losses on our premiums receivable balance for the indicated periods: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Balance at beginning of period $ 20,000 17,100 $ 18,900 16,100 Current period change for expected credit losses 2,488 1,515 4,272 3,425 Write-offs charged against the allowance for credit losses (1,720) (1,047) (2,776) (2,211) Recoveries 332 332 704 586 Allowance for credit losses, end of period $ 21,100 17,900 $ 21,100 17,900 For a discussion of the methodology used to evaluate our estimate of expected credit losses on premiums receivable, refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2023 Annual Report.

Reinsurance

Reinsurance	6 Months Ended
	Jun. 30, 2024
Reinsurance Disclosures [Abstract]
Reinsurance	Reinsurance We evaluate and monitor the financial condition of our reinsurers under voluntary reinsurance arrangements to minimize our exposure to significant losses from reinsurer insolvencies. The following tables provide (i) a disaggregation of our reinsurance recoverable balance by financial strength rating, and (ii) an aging analysis of our past due reinsurance recoverable balances as of June 30, 2024, and December 31, 2023: June 30, 2024 ($ in thousands) Current Past Due Total Reinsurance Recoverables Financial strength rating of rated reinsurers A++ $ 83,944 671 84,615 A+ 392,094 566 392,660 A 116,631 1,113 117,744 A- 4,991 89 5,080 Total rated reinsurers 597,660 2,439 600,099 Non-rated reinsurers Federal and state pools 83,241 — 83,241 Other than federal and state pools 3,785 163 3,948 Total non-rated reinsurers 87,026 163 87,189 Total reinsurance recoverable, gross $ 684,686 2,602 687,288 Less: allowance for credit losses (1,700) Total reinsurance recoverable, net 685,588 December 31, 2023 ($ in thousands) Current Past Due Total Reinsurance Recoverables Financial strength rating of rated reinsurers A++ $ 82,466 21 82,487 A+ 371,132 2,887 374,019 A 111,883 1,380 113,263 A- 3,596 89 3,685 Total rated reinsurers 569,077 4,377 573,454 Non-rated reinsurers Federal and state pools 80,506 — 80,506 Other than federal and state pools 4,488 77 4,565 Total non-rated reinsurers 84,994 77 85,071 Total reinsurance recoverable, gross $ 654,071 4,454 658,525 Less: allowance for credit losses (1,700) Total reinsurance recoverable, net 656,825 The following table provides a roll forward of the allowance for credit losses on our reinsurance recoverable balance for the periods indicated: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Balance at beginning of period $ 1,700 2,300 $ 1,700 1,600 Current period change for expected credit losses — (500) — 200 Write-offs charged against the allowance for credit losses — — — — Recoveries — — — — Allowance for credit losses, end of period $ 1,700 1,800 $ 1,700 1,800 For a discussion of the methodology used to evaluate our estimate of expected credit losses on our reinsurance recoverable balance, refer to Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of our 2023 Annual Report. The following table lists direct, assumed, and ceded reinsurance amounts for premiums written, premiums earned, and loss and loss expense incurred for the indicated periods. For more information about reinsurance, refer to Note 9. “Reinsurance” in Item 8. “Financial Statements and Supplementary Data.” of our 2023 Annual Report. Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Premiums written: Direct $ 1,399,738 1,232,496 $ 2,715,649 2,365,256 Assumed 6,413 5,577 12,398 10,971 Ceded (180,050) (153,166) (345,325) (291,552) Net 1,226,101 1,084,907 2,382,722 2,084,675 Premiums earned: Direct 1,242,696 1,073,498 2,448,064 2,105,726 Assumed 5,779 5,968 11,970 12,258 Ceded (168,244) (137,316) (328,859) (273,498) Net 1,080,231 942,150 2,131,175 1,844,486 Loss and loss expense incurred: Direct 1,009,819 698,994 1,763,386 1,312,223 Assumed 5,058 5,678 11,039 10,933 Ceded (89,329) (58,542) (144,585) (109,588) Net $ 925,548 646,130 $ 1,629,840 1,213,568 The increase in direct loss and loss expense incurred in Second Quarter 2024 and Six Months 2024 compared to the same prior-year periods was primarily due to (i) unfavorable prior year casualty reserve development of $176.0 million in Second Quarter 2024, compared to $3.5 million of favorable development in Second Quarter 2023, and (ii) unfavorable prior year casualty reserve development of $211.0 million in Six Months 2024, compared to $16.5 million of favorable development in Six Months 2023.

Reserve for Loss and Loss Expen

Reserve for Loss and Loss Expense	6 Months Ended
	Jun. 30, 2024
Insurance Loss Reserves [Abstract]
Reserve for Loss and Loss Expense	Reserve for Loss and Loss Expense The table below provides a roll forward of the reserve for loss and loss expense for beginning and ending reserve balances: Six Months ended June 30, ($ in thousands) 2024 2023 Gross reserve for loss and loss expense, at beginning of period $ 5,336,911 5,144,821 Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of period 618,601 757,513 Net reserve for loss and loss expense, at beginning of period 4,718,310 4,387,308 Incurred loss and loss expense for claims occurring in the: Current year 1,442,719 1,221,635 Prior years 187,121 (8,067) Total incurred loss and loss expense 1,629,840 1,213,568 Paid loss and loss expense for claims occurring in the: Current year 347,501 320,026 Prior years 753,658 720,314 Total paid loss and loss expense 1,101,159 1,040,340 Net reserve for loss and loss expense, at end of period 5,246,991 4,560,536 Add: Reinsurance recoverable on unpaid loss and loss expense, at end of period 656,534 616,487 Gross reserve for loss and loss expense, at end of period $ 5,903,525 5,177,023 Prior year reserve development in Six Months 2024 was unfavorable by $187.1 million, consisting of $211.0 million of unfavorable casualty reserve development, partially offset by $23.9 million of favorable property reserve development. The unfavorable casualty reserve development was driven by our Standard Commercial Lines segment, which included (i) $216.0 million in our general liability line of business, primarily driven by increased severities in accident years 2020 through 2023, (ii) $10.0 million in our commercial automobile line of business, partially offset by (iii) $15.0 million of favorable casualty reserve development in our workers compensation line of business. Additionally, in our Standard Personal Lines segment, we had unfavorable casualty reserve development of $5.0 million in our personal automobile line of business, offset by favorable development of $5.0 million in our homeowners line of business. Prior year reserve development in Six Months 2023 was favorable by $8.1 million, consisting of $16.5 million of favorable casualty reserve development, partially offset by $8.4 million of unfavorable property reserve development. The favorable casualty reserve development included $17.5 million in our workers compensation line of business and $5.0 million in our Excess and Surplus ("E&S") casualty lines of business, partially offset by $6.0 million of unfavorable casualty reserve development in our personal automobile line of business.

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2024
Segment Reporting [Abstract]
Segment Information	Segment Information We evaluate the results of our four reportable segments as follows: • Our Standard Commercial Lines, Standard Personal Lines, and E&S Lines are evaluated on (i) before and after-tax underwriting results (net premiums earned, incurred loss and loss expense, policyholder dividends, policy acquisition costs, and other underwriting expenses), (ii) their return on equity ("ROE") contribution, and (iii) their combined ratios. • Our Investments segment is primarily evaluated on after-tax net investment income and its ROE contribution. After-tax net realized and unrealized gains and losses are also included in our Investments segment results. In computing each segment's results, we do not make adjustments for interest expense or corporate expenses. No segment has a separate investment portfolio or allocated assets. The following summaries present revenues (net investment income and net realized and unrealized gains and losses on investments in the case of the Investments segment) and pre-tax income for the individual segments: Revenue by Segment Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Standard Commercial Lines: Net premiums earned: General liability $ 280,097 254,510 $ 553,512 497,859 Commercial automobile 260,652 225,067 512,372 442,438 Commercial property 168,511 141,348 330,064 276,640 Workers compensation 82,316 88,746 170,093 172,930 Businessowners' policies 41,641 34,385 81,562 67,556 Bonds 12,468 11,619 24,556 23,016 Other 7,808 7,034 15,444 13,885 Miscellaneous income 5,214 5,568 12,348 7,749 Total Standard Commercial Lines revenue 858,707 768,277 1,699,951 1,502,073 Standard Personal Lines: Net premiums earned: Personal automobile 57,544 48,230 114,504 93,144 Homeowners 46,055 36,902 90,168 71,915 Other 2,822 2,038 5,595 3,981 Miscellaneous income 594 536 1,235 989 Total Standard Personal Lines revenue 107,015 87,706 211,502 170,029 E&S Lines: Net premiums earned: Casualty lines 73,887 62,151 145,525 122,968 Property lines 46,430 30,120 87,780 58,154 Miscellaneous income 27 — 53 — Total E&S Lines revenue 120,344 92,271 233,358 181,122 Investments: Net investment income earned 108,642 97,696 216,491 189,202 Net realized and unrealized investment gains (losses) 1,297 (5,426) (338) (2,082) Total Investments revenue 109,939 92,270 216,153 187,120 Total revenues $ 1,196,005 1,040,524 $ 2,360,964 2,040,344 Income (Loss) Before and After Federal Income Tax Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Standard Commercial Lines: Underwriting income (loss), before federal income tax $ (160,881) 22,146 $ (150,500) 61,067 Underwriting income (loss), after federal income tax (127,096) 17,495 (118,895) 48,243 Combined ratio 118.8 % 97.1 108.9 95.9 ROE contribution (18.4) 2.8 (8.6) 4.1 Standard Personal Lines: Underwriting income (loss), before federal income tax $ (19,301) (23,060) $ (24,636) (36,133) Underwriting income (loss), after federal income tax (15,248) (18,217) (19,462) (28,545) Combined ratio 118.1 % 126.5 111.7 121.4 ROE contribution (2.2) (2.9) (1.4) (2.4) E&S Lines: Underwriting income (loss), before federal income tax $ 6,501 (612) $ 20,486 12,723 Underwriting income (loss), after federal income tax 5,136 (483) 16,184 10,051 Combined ratio 94.6 % 100.7 91.2 93.0 ROE contribution 0.7 (0.1) 1.2 0.8 Investments: Net investment income earned $ 108,642 97,696 $ 216,491 189,202 Net realized and unrealized investment gains (losses) 1,297 (5,426) (338) (2,082) Total investments segment income, before federal income tax 109,939 92,270 216,153 187,120 Tax on investments segment income 22,652 18,745 44,518 37,901 Total investments segment income, after federal income tax $ 87,287 73,525 $ 171,635 149,219 ROE contribution of after-tax net investment income earned 12.5 12.6 12.5 12.5 Reconciliation of Segment Results to Income (Loss) Before Federal Income Tax Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Underwriting income (loss) Standard Commercial Lines $ (160,881) 22,146 $ (150,500) 61,067 Standard Personal Lines (19,301) (23,060) (24,636) (36,133) E&S Lines 6,501 (612) 20,486 12,723 Investment income 109,939 92,270 216,153 187,120 Total all segments (63,742) 90,744 61,503 224,777 Interest expense (7,202) (7,258) (14,383) (14,424) Corporate expenses (9,154) (9,329) (24,652) (21,437) Income (loss), before federal income tax $ (80,098) 74,157 $ 22,468 188,916 Preferred stock dividends (2,300) (2,300) (4,600) (4,600) Income (loss) available to common stockholders, before federal income tax $ (82,398) 71,857 $ 17,868 184,316

Retirement Plans

Retirement Plans	6 Months Ended
	Jun. 30, 2024
Retirement Benefits [Abstract]
Retirement Plans	Retirement Plans The primary pension plan for our employees is the Retirement Income Plan for Selective Insurance Company of America (the “Pension Plan”). The plan is closed to new entrants, and benefits ceased accruing under the Pension Plan after March 31, 2016. For more information about Selective Insurance Company of America's ("SICA") retirement plans, see Note 15. “Retirement Plans” in Item 8. “Financial Statements and Supplementary Data.” of our 2023 Annual Report. The following tables provide information about the Pension Plan: Pension Plan Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Net Periodic Pension Cost (Benefit): Interest cost $ 3,888 3,866 $ 7,776 7,732 Expected return on plan assets (5,383) (5,772) (10,765) (11,545) Amortization of unrecognized net actuarial loss 955 750 1,910 1,501 Total net periodic pension cost (benefit) 1 $ (540) (1,156) $ (1,079) (2,312) 1 The components of net periodic pension cost (benefit) are included within "Loss and loss expense incurred" and "Other insurance expenses" on the Consolidated Statements of Income. Pension Plan Six Months ended June 30, 2024 2023 Weighted-Average Expense Assumptions: Discount rate 5.02 % 5.21 % Effective interest rate for calculation of interest cost 4.91 5.09 Expected return on plan assets 6.40 6.90

Comprehensive Income (Loss)

Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2024
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Comprehensive Income (Loss)	Comprehensive Income (Loss) The components of comprehensive income (loss), both gross and net of tax, for Second Quarter 2024 and Six Months 2024 and Second Quarter 2023 and Six Months 2023 were as follows: Second Quarter 2024 ($ in thousands) Gross Tax Net Net income (loss) $ (80,098) (16,779) (63,319) Components of OCI: Unrealized gains (losses) on investment securities : Unrealized holding gains (losses) during the period (8,347) (1,753) (6,594) Unrealized gains (losses) on securities with credit loss recognized in earnings (3,705) (778) (2,927) Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities 43 10 33 Credit loss (benefit) expense 1,233 258 975 Total unrealized gains (losses) on investment securities (10,776) (2,263) (8,513) Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 967 203 764 Total defined benefit pension and post-retirement plans 967 203 764 Other comprehensive income (loss) (9,809) (2,060) (7,749) Comprehensive income (loss) $ (89,907) (18,839) (71,068) Second Quarter 2023 ($ in thousands) Gross Tax Net Net income (loss) $ 74,157 15,549 58,608 Components of OCI: Unrealized gains (losses) on investment securities: Unrealized holding gains (losses) during the period (60,681) (12,744) (47,937) Unrealized gains (losses) on securities with credit loss recognized in earnings (6,030) (1,266) (4,764) Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities 9,383 1,970 7,413 Credit loss (benefit) expense (864) (181) (683) Total unrealized gains (losses) on investment securities (58,192) (12,221) (45,971) Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 757 159 598 Total defined benefit pension and post-retirement plans 757 159 598 Other comprehensive income (loss) (57,435) (12,062) (45,373) Comprehensive income (loss) $ 16,722 3,487 13,235 Six Months 2024 ($ in thousands) Gross Tax Net Net income (loss) $ 22,468 3,269 19,199 Components of OCI: Unrealized gains (losses) on investment securities : Unrealized holding gains (losses) during the period (23,907) (5,020) (18,887) Unrealized gains (losses) on securities with credit loss recognized in earnings (6,837) (1,436) (5,401) Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities (35) (7) (28) Credit loss (benefit) expense 3,883 815 3,068 Total unrealized gains (losses) on investment securities (26,896) (5,648) (21,248) Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 1,934 406 1,528 Total defined benefit pension and post-retirement plans 1,934 406 1,528 Other comprehensive income (loss) (24,962) (5,242) (19,720) Comprehensive income (loss) $ (2,494) (1,973) (521) Six Months 2023 ($ in thousands) Gross Tax Net Net income (loss) $ 188,916 37,734 151,182 Components of OCI: Unrealized gains (losses) on investment securities: Unrealized holding gains (losses) during the period 5,244 1,102 4,142 Unrealized gains (losses) on securities with credit loss recognized in earnings 16,401 3,444 12,957 Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities 15,487 3,252 12,235 Credit loss (benefit) expense (10,393) (2,183) (8,210) Total unrealized gains (losses) on investment securities 26,739 5,615 21,124 Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 1,514 318 1,196 Total defined benefit pension and post-retirement plans 1,514 318 1,196 Other comprehensive income (loss) 28,253 5,933 22,320 Comprehensive income (loss) $ 217,169 43,667 173,502 The balances of, and changes in, each component of accumulated other comprehensive income (loss) ("AOCI") (net of taxes) as of June 30, 2024, were as follows: June 30, 2024 Net Unrealized Gains (Losses) on Investment Securities Defined Benefit Pension and Post-Retirement Plans Total AOCI ($ in thousands) Credit Loss Related 1 All Investments Balance, December 31, 2023 $ (84,442) (194,628) (279,070) (93,931) (373,001) OCI before reclassifications (5,401) (18,887) (24,288) — (24,288) Amounts reclassified from AOCI 3,068 (28) 3,040 1,528 4,568 Net current period OCI (2,333) (18,915) (21,248) 1,528 (19,720) Balance, June 30, 2024 $ (86,775) (213,543) (300,318) (92,403) (392,721) 1 Represents change in unrealized gains (losses) on securities with credit loss recognized in earnings. The reclassifications out of AOCI were as follows: Quarter ended June 30, Six Months ended June 30, Affected Line Item in the Unaudited Consolidated Statements of Income ($ in thousands) 2024 2023 2024 2023 Net realized (gains) losses on disposals and intent-to-sell AFS securities Net realized (gains) losses $ 43 9,383 $ (35) 15,487 Net realized and unrealized investment gains (losses) Tax (benefit) expense (10) (1,970) 7 (3,252) Total federal income tax expense (benefit) Net of taxes 33 7,413 (28) 12,235 Net income (loss) Credit loss related Credit loss (benefit) expense 1,233 (864) 3,883 (10,393) Net realized and unrealized investment gains (losses) Tax (benefit) expense (258) 181 (815) 2,183 Total federal income tax expense (benefit) Net of taxes 975 (683) 3,068 (8,210) Net income (loss) Defined benefit pension and post-retirement life plans Net actuarial loss 223 173 445 348 Loss and loss expense incurred Net actuarial loss 744 584 1,489 1,166 Other insurance expenses Total 967 757 1,934 1,514 Income (loss) before federal income tax Tax (benefit) expense (203) (159) (406) (318) Total federal income tax expense (benefit) Net of taxes 764 598 1,528 1,196 Net income (loss) Total reclassifications for the period $ 1,772 7,328 $ 4,568 5,221 Net income (loss)

Earnings per Common Share

Earnings per Common Share	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings per Common Share The following table presents the calculations of earnings per common share ("EPS") on a basic and diluted basis: Quarter ended June 30, Six Months ended June 30, (in thousands, except per share amounts) 2024 2023 2024 2023 Net income (loss) available to common stockholders: $ (65,619) 56,308 $ 14,599 146,582 Weighted average common shares outstanding: Weighted average common shares outstanding - basic 60,897 60,614 60,862 60,575 Effect of dilutive securities - stock compensation plans — 323 382 343 Weighted average common shares outstanding - diluted 60,897 60,937 61,244 60,918 EPS: Basic $ (1.08) 0.93 $ 0.24 2.42 Diluted (1.08) 0.92 0.24 2.41 There were 0.4 million common stock equivalents related to our stock compensation plans in Second Quarter 2024 that were not included in the computation of diluted EPS, as we recorded a net loss available to common stockholders in the quarter and the effect of these items would have been anti-dilutive to our EPS computation.

Litigation

Litigation	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Litigation	Litigation As of June 30, 2024, we do not believe we are involved in any legal action that could have a material adverse effect on our consolidated financial condition, results of operations, or cash flows. In the ordinary course of conducting business, we are parties in various legal actions. Most are claims litigation involving our ten insurance subsidiaries (collectively referred to as "Insurance Subsidiaries") as (i) liability insurers defending or providing indemnity for third-party claims brought against our customers, (ii) insurers defending first-party coverage claims brought against them, or (iii) liability insurers seeking declaratory judgment on our insurance coverage obligations. We account for such activity by establishing unpaid loss and loss expense reserves. Considering potential losses and defense costs reserves, we expect that any potential ultimate liability for ordinary course claims litigation will not be material to our consolidated financial condition, results of operations, or cash flows. All our commercial property and businessowners' policies require direct physical loss of or damage to property by a covered cause of loss. All our standard lines commercial property and businessowners' policies also include or attach an exclusion that states all loss or property damage caused by or resulting from any virus, bacterium, or other microorganism that induces or is capable of inducing physical distress, illness, or disease is not a covered cause of loss ("Virus Exclusion"). Whether COVID-19-related contamination, the existence of the COVID-19 pandemic, and the resulting COVID-19-related government shutdown orders cause physical loss of or damage to property is the subject of much public debate and first-party coverage litigation against some insurers, including us. The Virus Exclusion is also the subject of first-party coverage litigation against some insurers, including us. To date, insurers (including us) have prevailed in the majority of these suits, with most decisions holding that COVID-19 does not cause physical loss of or damage to property and the Virus Exclusion is valid. Nonetheless, these two matters continue to be litigated in trial courts, are subject to review by state and federal appellate courts, and their ultimate outcome cannot be assured. From time to time, our Insurance Subsidiaries also are named as defendants in other legal actions, some asserting claims for substantial amounts. Plaintiffs may style these actions as class actions and seek judicial certification of a state or national class for allegations involving our business practices, such as improper medical provider reimbursement under workers compensation and personal and commercial automobile insurance policies or improper reimbursement for automobile parts. Similarly, our Insurance Subsidiaries can be named defendants in individual actions seeking extra-contractual damages, punitive damages, or penalties, often alleging bad faith in handling insurance claims. We believe that we have valid defenses to these allegations and account for such activity by establishing unpaid loss and loss expense reserves. Considering estimated losses and defense costs reserves, we expect that any potential ultimate liability for these other legal actions will not be material to our consolidated financial condition. Litigation outcomes are inherently unpredictable and the amounts sought in certain actions are large or indeterminate, so adverse outcomes could potentially have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net income (loss)	$ (63,319)	$ 58,608	$ 19,199	$ 151,182

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Statements of Cash Flows (Table

Statements of Cash Flows (Tables)	6 Months Ended
	Jun. 30, 2024
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Supplemental cash flow information was as follows: Six Months ended June 30, ($ in thousands) 2024 2023 Cash paid (received) during the period for: Interest $ 14,209 14,164 Federal income tax 46,000 34,000 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases 3,884 4,038 Operating cash flows from financing leases 65 20 Financing cash flows from finance leases 1,266 1,231 Non-cash items: Corporate actions related to fixed income securities, available-for-sale ("AFS") 1 10,250 23,150 Corporate actions related to equity securities 1 29,250 — Assets acquired under finance lease arrangements 5,947 — Assets acquired under operating lease arrangements 10,257 4,509 Non-cash purchase of property and equipment 9 — 1 Examples of corporate actions include like-kind exchanges, non-cash acquisitions, and stock splits.
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash and restricted cash reported within the Consolidated Balance Sheets that equate to the amount reported in the Consolidated Statements of Cash Flows: ($ in thousands) June 30, 2024 December 31, 2023 Cash $ 160 180 Restricted cash 10,748 13,092 Total cash and restricted cash shown in the Consolidated Statements of Cash Flows $ 10,908 13,272
Schedule of Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash and restricted cash reported within the Consolidated Balance Sheets that equate to the amount reported in the Consolidated Statements of Cash Flows: ($ in thousands) June 30, 2024 December 31, 2023 Cash $ 160 180 Restricted cash 10,748 13,092 Total cash and restricted cash shown in the Consolidated Statements of Cash Flows $ 10,908 13,272

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2024
Investments [Abstract]
Schedule of Available-for-Sale Securities	Information regarding our AFS securities as of June 30, 2024 and December 31, 2023, were as follows: June 30, 2024 Cost/ Allowance for Credit Losses Unrealized Unrealized Fair ($ in thousands) AFS fixed income securities: U.S. government and government agencies $ 170,819 — 56 (19,907) 150,968 Foreign government 10,687 (26) — (1,427) 9,234 Obligations of states and political subdivisions 558,455 (639) 770 (33,151) 525,435 Corporate securities 2,987,824 (15,950) 17,803 (143,725) 2,845,952 Collateralized loan obligations ("CLO") and other asset-backed securities ("ABS") 1,972,687 (3,022) 16,359 (69,904) 1,916,120 Residential mortgage-backed securities ("RMBS") 1,624,078 (11,660) 2,954 (111,420) 1,503,952 Commercial mortgage-backed securities ("CMBS") 755,948 (12) 814 (39,378) 717,372 Total AFS fixed income securities $ 8,080,498 (31,309) 38,756 (418,912) 7,669,033 December 31, 2023 Cost/ Allowance for Credit Losses Unrealized Unrealized Fair ($ in thousands) AFS fixed income securities: U.S. government and government agencies $ 223,157 — 139 (18,261) 205,035 Foreign government 11,140 (35) — (1,302) 9,803 Obligations of states and political subdivisions 612,938 (669) 2,623 (28,927) 585,965 Corporate securities 2,834,048 (12,999) 28,078 (137,888) 2,711,239 CLO and other ABS 1,911,831 (2,854) 11,855 (86,005) 1,834,827 RMBS 1,568,960 (11,649) 6,023 (85,851) 1,477,483 CMBS 718,623 (6) 1,358 (45,130) 674,845 Total AFS fixed income securities $ 7,880,697 (28,212) 50,076 (403,364) 7,499,197
Schedule of Debt Securities, Available-for-Sale, Allowance for Credit Loss	The following tables provide a roll forward of the allowance for credit losses on our AFS fixed income securities for the indicated periods: Quarter ended June 30, 2024 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 29 — — (3) — — 26 Obligations of states and political subdivisions 695 18 — (74) — — 639 Corporate securities 15,442 846 — (126) (212) — 15,950 CLO and other ABS 2,627 271 — 126 (2) — 3,022 RMBS 11,580 — — 171 (91) — 11,660 CMBS 8 — — 4 — — 12 Total AFS fixed income securities $ 30,381 1,135 — 98 (305) — 31,309 Quarter ended June 30, 2023 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 36 — — (2) — — 34 Obligations of states and political subdivisions 737 67 — (35) — — 769 Corporate securities 16,756 1,438 — (1,070) (939) (36) 16,149 CLO and other ABS 3,895 622 — (1,595) (7) — 2,915 RMBS 11,740 1 — (50) (141) — 11,550 CMBS 390 — — (240) (142) — 8 Total AFS fixed income securities $ 33,554 2,128 — (2,992) (1,229) (36) 31,425 Six Months ended June 30, 2024 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 35 — — (3) (6) — 26 Obligations of states and political subdivisions 669 37 — (59) (8) — 639 Corporate securities 12,999 2,362 — 1,166 (568) (9) 15,950 CLO and other ABS 2,854 427 — (255) (4) — 3,022 RMBS 11,649 — — 202 (191) — 11,660 CMBS 6 2 — 4 — — 12 Total AFS fixed income securities $ 28,212 2,828 — 1,055 (777) (9) 31,309 Six Months ended June 30, 2023 Beginning Balance Current Provision for Securities without Prior Allowance Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities Reductions for Securities Sold Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period Ending Balance ($ in thousands) Foreign government $ 284 — — (250) — — 34 Obligations of states and political subdivisions 1,024 67 — (239) (83) — 769 Corporate securities 30,330 4,141 — (14,884) (3,387) (51) 16,149 CLO and other ABS 2,375 677 — (127) (10) — 2,915 RMBS 11,597 8 — 174 (229) — 11,550 CMBS 111 1 — 39 (143) — 8 Total AFS fixed income securities $ 45,721 4,894 — (15,287) (3,852) (51) 31,425
Schedule of Quantitative Information about Unrealized Losses on AFS	Quantitative information about unrealized losses on our AFS portfolio follows: June 30, 2024 Less than 12 months 12 months or longer Total ($ in thousands) Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized AFS fixed income securities: U.S. government and government agencies $ 33,667 (52) 107,306 (19,855) 140,973 (19,907) Foreign government — — 9,234 (1,427) 9,234 (1,427) Obligations of states and political subdivisions 128,665 (1,644) 329,528 (31,507) 458,193 (33,151) Corporate securities 358,779 (3,477) 1,477,738 (140,248) 1,836,517 (143,725) CLO and other ABS 368,307 (6,432) 798,783 (63,472) 1,167,090 (69,904) RMBS 385,794 (6,133) 878,915 (105,287) 1,264,709 (111,420) CMBS 75,052 (779) 550,901 (38,599) 625,953 (39,378) Total AFS fixed income securities $ 1,350,264 (18,517) 4,152,405 (400,395) 5,502,669 (418,912) December 31, 2023 Less than 12 months 12 months or longer Total ($ in thousands) Fair Unrealized Fair Value Unrealized Fair Value Unrealized AFS fixed income securities: U.S. government and government agencies $ 77,698 (188) 108,578 (18,073) 186,276 (18,261) Foreign government 1,552 (87) 8,251 (1,215) 9,803 (1,302) Obligations of states and political subdivisions 137,031 (962) 290,964 (27,965) 427,995 (28,927) Corporate securities 263,423 (6,369) 1,439,422 (131,519) 1,702,845 (137,888) CLO and other ABS 278,940 (7,120) 984,175 (78,885) 1,263,115 (86,005) RMBS 351,976 (4,765) 757,914 (81,086) 1,109,890 (85,851) CMBS 130,189 (2,995) 471,256 (42,135) 601,445 (45,130) Total AFS fixed income securities $ 1,240,809 (22,486) 4,060,560 (380,878) 5,301,369 (403,364)
Schedule of Fixed Maturity Securities by Contractual Maturities	AFS and held-to-maturity ("HTM") fixed income securities at June 30, 2024, by contractual maturity are shown below. The maturities of RMBS, CMBS, CLO and other ABS securities were calculated using each security's estimated average life. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations with or without call or prepayment penalties. AFS HTM ($ in thousands) Fair Value Carrying Value Fair Value Due in one year or less $ 587,352 820 810 Due after one year through five years 3,507,774 14,209 13,662 Due after five years through 10 years 2,827,999 4,467 4,084 Due after 10 years 745,908 — — Total fixed income securities $ 7,669,033 19,496 18,556
Schedule of Alternative Investment Portfolio by Strategy and Remaining Commitment Amount and Maximum Exposure to Loss Associated with Each Strategy	The following table summarizes our alternative investment portfolio by strategy: June 30, 2024 December 31, 2023 ($ in thousands) Carrying Value Remaining Commitment Maximum Exposure to Loss Carrying Value Remaining Commitment Maximum Exposure to Loss Alternative Investments Private equity $ 319,236 148,558 467,794 301,759 131,885 433,644 Private credit 52,106 98,417 150,523 54,500 89,401 143,901 Real assets 43,438 42,336 85,774 39,520 33,040 72,560 Total alternative investments $ 414,780 289,311 704,091 395,779 254,326 650,105
Schedule of Aggregated Summarized Income Statement Financial Information for Partnerships in Alternative Investment Portfolio	The following table shows gross summarized financial information for our alternative investments portfolio, including the portion we do not own. As the majority of these investments report results to us on a one quarter lag, the summarized financial statement information is for 3- and 6-month periods ended March 31: Income Statement Information Quarter ended June 30, Six Months ended June 30, ($ in millions) 2024 2023 2024 2023 Net investment income (loss) $ 242.4 (70.6) $ (103.6) (141.3) Realized gains 1,554.2 922.0 3,385.1 2,644.3 Net change in unrealized appreciation (depreciation) 2,850.2 3,754.0 6,669.2 5,197.8 Net income $ 4,646.8 4,605.4 $ 9,950.7 7,700.8 Alternative investment income included in "Net investment income earned" on our Consolidated Statements of Income $ 10.5 11.4 $ 17.4 19.2
Schedule of Securities Pledged as Collateral	The following table summarizes the market value of these securities at June 30, 2024: ($ in millions) FHLBI Collateral FHLBNY Collateral State and Total U.S. government and government agencies $ — — 19.9 19.9 Obligations of states and political subdivisions — — 4.2 4.2 RMBS 64.2 23.2 — 87.4 CMBS 2.1 8.3 — 10.4 Total pledged as collateral $ 66.3 31.5 24.1 121.9
Schedule of Pre-Tax Net Investment Income Earned	The components of pre-tax net investment income earned were as follows: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Fixed income securities $ 93,935 83,916 $ 188,037 164,003 Commercial mortgage loans ("CMLs") 3,145 2,199 5,939 4,164 Equity securities 1,877 2,236 6,785 3,441 Short-term investments 4,680 2,892 8,199 7,542 Alternative investments 10,517 11,396 17,398 19,164 Other investments 118 188 381 231 Investment expenses (5,630) (5,131) (10,248) (9,343) Net investment income earned $ 108,642 97,696 $ 216,491 189,202
Schedule of Realized and Unrealized Gains (Losses) on Securities	The following table summarizes net realized and unrealized investment gains and losses for the periods indicated: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Gross gains on sales $ 4,387 1,156 $ 6,522 4,940 Gross losses on sales (1,251) (11,952) (3,216) (24,882) Net realized gains (losses) on disposals 3,136 (10,796) 3,306 (19,942) Net unrealized gains (losses) on equity securities (93) 4,925 599 8,173 Net credit loss benefit (expense) on fixed income securities, AFS (1,233) 864 (3,883) 10,393 Net credit loss benefit (expense) on CMLs (32) (78) 136 (61) Losses on securities for which we have the intent to sell (481) (341) (496) (645) Net realized and unrealized investment gains (losses) $ 1,297 (5,426) $ (338) (2,082)
Schedule of Unrealized Gain (Loss) on Equity Securities	Net unrealized gains and losses recognized in income on equity securities, as reflected in the table above, included the following: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Unrealized gains (losses) recognized in income on equity securities: On securities remaining in our portfolio at end of period $ 2,617 2,784 $ 2,906 2,685 On securities sold in period (2,710) 2,141 (2,307) 5,488 Total unrealized gains (losses) recognized in income on equity securities $ (93) 4,925 $ 599 8,173

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Financial Liabilities	The following table presents the carrying amounts and fair values of our financial liabilities as of June 30, 2024, and December 31, 2023: June 30, 2024 December 31, 2023 ($ in thousands) Carrying Amount Fair Value Carrying Amount Fair Value Financial Liabilities Long-term debt: 7.25% Senior Notes $ 49,928 51,301 49,926 53,047 6.70% Senior Notes 99,577 99,393 99,565 104,039 5.375% Senior Notes 294,574 283,037 294,523 288,787 3.03% borrowings from FHLBI 60,000 57,638 60,000 57,932 Subtotal long-term debt 504,079 491,369 504,014 503,805 Unamortized debt issuance costs (2,596) (2,704) Finance lease obligations 7,318 2,636 Total long-term debt $ 508,801 503,946
Schedule of Fair Value of Financial Assets	The following tables provide quantitative disclosures of our financial assets that were measured and recorded at fair value at June 30, 2024, and December 31, 2023: June 30, 2024 Fair Value Measurements Using ($ in thousands) Assets Quoted Prices in Significant Other Significant Unobservable Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 150,968 33,453 117,515 — Foreign government 9,234 — 9,234 — Obligations of states and political subdivisions 525,435 — 517,781 7,654 Corporate securities 2,845,952 — 2,552,239 293,713 CLO and other ABS 1,916,120 — 1,652,400 263,720 RMBS 1,503,952 — 1,499,066 4,886 CMBS 717,372 — 717,023 349 Total AFS fixed income securities 7,669,033 33,453 7,065,258 570,322 Equity securities: Common stock 1 190,141 34,815 — 1,067 Preferred stock 1,823 1,823 — — Total equity securities 191,964 36,638 — 1,067 Short-term investments 417,346 400,906 16,440 — Total assets measured at fair value $ 8,278,343 470,997 7,081,698 571,389 December 31, 2023 Fair Value Measurements Using ($ in thousands) Assets Quoted Prices in Significant Significant Unobservable Description Measured on a recurring basis: AFS fixed income securities: U.S. government and government agencies $ 205,035 34,056 170,979 — Foreign government 9,803 — 9,803 — Obligations of states and political subdivisions 585,965 — 578,131 7,834 Corporate securities 2,711,239 — 2,413,907 297,332 CLO and other ABS 1,834,827 — 1,589,514 245,313 RMBS 1,477,483 — 1,477,483 — CMBS 674,845 — 674,489 356 Total AFS fixed income securities 7,499,197 34,056 6,914,306 550,835 Equity securities: Common stock 1 185,339 20,582 — 854 Preferred stock 1,816 1,816 — — Total equity securities 187,155 22,398 — 854 Short-term investments 309,317 308,512 805 — Total assets measured at fair value $ 7,995,669 364,966 6,915,111 551,689 1
Schedule of Summary of the Changes in Fair Value of Securities Using Level 3 Inputs	The following tables provide a summary of Level 3 changes in Six Months 2024 and Six Months 2023: June 30, 2024 ($ in thousands) Obligations of States and Political Subdivisions Corporate Securities CLO and Other ABS RMBS CMBS Common Stock Total Fair value, December 31, 2023 $ 7,834 297,332 245,313 — 356 854 551,689 Total net gains (losses) for the period included in: Other comprehensive income (loss) ("OCI") (112) 1,203 969 — (2) — 2,058 Net realized and unrealized gains (losses) — 218 39 — — 213 470 Net investment income earned — (494) (7) — (1) — (502) Purchases — 5,261 30,119 4,886 — — 40,266 Sales — — — — — — — Issuances — — — — — — — Settlements (68) (7,269) (4,726) — (4) — (12,067) Transfers into Level 3 — 28,896 19,537 — — — 48,433 Transfers out of Level 3 — (31,434) (27,524) — — — (58,958) Fair value, June 30, 2024 $ 7,654 293,713 263,720 4,886 349 1,067 571,389 Change in unrealized gains (losses) for the period included in earnings for assets held at period end — 226 39 — — 213 478 Change in unrealized gains (losses) for the period included in OCI for assets held at period end (112) 850 969 — (2) — 1,705 June 30, 2023 ($ in thousands) Obligation of state and Political Subdivisions Corporate Securities CLO and Other ABS CMBS Common Stock Total Fair value, December 31, 2022 $ 6,661 187,980 153,342 375 897 349,255 Total net gains (losses) for the period included in: OCI (7) 1,857 (1,168) 64 — 746 Net realized and unrealized gains (losses) 62 251 17 — (235) 95 Net investment income earned — 112 (20) (263) — (171) Purchases — 58,586 39,713 — — 98,299 Sales — — — — — — Issuances — — — — — — Settlements — (5,535) (3,153) (21) — (8,709) Transfers into Level 3 — 2,238 14,148 2,848 — 19,234 Transfers out of Level 3 — — (953) (2,626) — (3,579) Fair value, June 30, 2023 $ 6,716 245,489 201,926 377 662 455,170 Change in unrealized gains (losses) for the period included in earnings for assets held at period end 62 251 17 — (235) 95 Change in unrealized gains (losses) for the period included in OCI for assets held at period end (7) 1,846 (1,168) 64 — 735
Schedule of Fair Value Measurement Inputs and Valuation Techniques	The following tables present quantitative information about the significant unobservable inputs used in the fair value measurements of Level 3 assets at June 30, 2024, and December 31, 2023: June 30, 2024 ($ in thousands) Assets Measured at Fair Value Valuation Techniques Unobservable Inputs Range Weighted Average Internal valuations: Corporate securities $ 154,075 Discounted Cash Flow Illiquidity Spread (4.4)% - 5.3% 1.8% CLO and other ABS 158,660 Discounted Cash Flow Illiquidity Spread 0.01% - 19.6% 2.5% Total internal valuations 312,735 Other 1 258,654 Total Level 3 securities $ 571,389 December 31, 2023 ($ in thousands) Assets Measured at Fair Value Valuation Techniques Unobservable Inputs Range Weighted Average Internal valuations: Corporate securities $ 135,524 Discounted Cash Flow Illiquidity Spread (4.4)% - 5.3% 1.9% CLO and other ABS 127,210 Discounted Cash Flow Illiquidity Spread 0.01% - 19.6% 2.4% Total internal valuations 262,734 Other 1 288,955 Total Level 3 securities $ 551,689 1
Schedule of Quantitative Information of Financial Assets and Liabilities, Disclosed at Fair Value	The following tables provide quantitative information about our financial assets and liabilities that were not measured at fair value, but were disclosed as such at June 30, 2024, and December 31, 2023: June 30, 2024 Fair Value Measurements Using ($ in thousands) Assets/ Quoted Prices in Significant Other Significant Financial Assets HTM: Corporate securities $ 18,556 — 18,556 — Total HTM fixed income securities 18,556 — 18,556 — CMLs $ 209,041 — — 209,041 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 51,301 — 51,301 — 6.70% Senior Notes 99,393 — 99,393 — 5.375% Senior Notes 283,037 — 283,037 — 3.03% borrowings from FHLBI 57,638 — 57,638 — Total long-term debt $ 491,369 — 491,369 — December 31, 2023 Fair Value Measurements Using ($ in thousands) Assets/ Quoted Prices in Significant Other Significant Financial Assets HTM: Corporate securities $ 21,923 — 21,923 — Total HTM fixed income securities 21,923 — 21,923 — CMLs $ 178,913 — — 178,913 Financial Liabilities Long-term debt: 7.25% Senior Notes $ 53,047 — 53,047 — 6.70% Senior Notes 104,039 — 104,039 — 5.375% Senior Notes 288,787 — 288,787 — 3.03% borrowings from FHLBI 57,932 — 57,932 — Total long-term debt $ 503,805 — 503,805 —

Allowance for Credit Losses o_2

Allowance for Credit Losses on Premiums Receivable (Tables)	6 Months Ended
	Jun. 30, 2024
Premiums Receivable Disclosure [Abstract]
Schedule of Allowance for Credit Losses on Premiums Receivable	The following table provides a roll forward of the allowance for credit losses on our premiums receivable balance for the indicated periods: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Balance at beginning of period $ 20,000 17,100 $ 18,900 16,100 Current period change for expected credit losses 2,488 1,515 4,272 3,425 Write-offs charged against the allowance for credit losses (1,720) (1,047) (2,776) (2,211) Recoveries 332 332 704 586 Allowance for credit losses, end of period $ 21,100 17,900 $ 21,100 17,900

Reinsurance (Tables)

Reinsurance (Tables)	6 Months Ended
	Jun. 30, 2024
Reinsurance Disclosures [Abstract]
Schedule of Reinsurance Recoverable, Credit Quality Indicator	The following tables provide (i) a disaggregation of our reinsurance recoverable balance by financial strength rating, and (ii) an aging analysis of our past due reinsurance recoverable balances as of June 30, 2024, and December 31, 2023: June 30, 2024 ($ in thousands) Current Past Due Total Reinsurance Recoverables Financial strength rating of rated reinsurers A++ $ 83,944 671 84,615 A+ 392,094 566 392,660 A 116,631 1,113 117,744 A- 4,991 89 5,080 Total rated reinsurers 597,660 2,439 600,099 Non-rated reinsurers Federal and state pools 83,241 — 83,241 Other than federal and state pools 3,785 163 3,948 Total non-rated reinsurers 87,026 163 87,189 Total reinsurance recoverable, gross $ 684,686 2,602 687,288 Less: allowance for credit losses (1,700) Total reinsurance recoverable, net 685,588 December 31, 2023 ($ in thousands) Current Past Due Total Reinsurance Recoverables Financial strength rating of rated reinsurers A++ $ 82,466 21 82,487 A+ 371,132 2,887 374,019 A 111,883 1,380 113,263 A- 3,596 89 3,685 Total rated reinsurers 569,077 4,377 573,454 Non-rated reinsurers Federal and state pools 80,506 — 80,506 Other than federal and state pools 4,488 77 4,565 Total non-rated reinsurers 84,994 77 85,071 Total reinsurance recoverable, gross $ 654,071 4,454 658,525 Less: allowance for credit losses (1,700) Total reinsurance recoverable, net 656,825
Schedule of Reinsurance Recoverable, Allowance for Credit Loss	The following table provides a roll forward of the allowance for credit losses on our reinsurance recoverable balance for the periods indicated: Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Balance at beginning of period $ 1,700 2,300 $ 1,700 1,600 Current period change for expected credit losses — (500) — 200 Write-offs charged against the allowance for credit losses — — — — Recoveries — — — — Allowance for credit losses, end of period $ 1,700 1,800 $ 1,700 1,800
Schedule of Direct, Assumed, and Ceded Reinsurance Amounts	The following table lists direct, assumed, and ceded reinsurance amounts for premiums written, premiums earned, and loss and loss expense incurred for the indicated periods. For more information about reinsurance, refer to Note 9. “Reinsurance” in Item 8. “Financial Statements and Supplementary Data.” of our 2023 Annual Report. Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Premiums written: Direct $ 1,399,738 1,232,496 $ 2,715,649 2,365,256 Assumed 6,413 5,577 12,398 10,971 Ceded (180,050) (153,166) (345,325) (291,552) Net 1,226,101 1,084,907 2,382,722 2,084,675 Premiums earned: Direct 1,242,696 1,073,498 2,448,064 2,105,726 Assumed 5,779 5,968 11,970 12,258 Ceded (168,244) (137,316) (328,859) (273,498) Net 1,080,231 942,150 2,131,175 1,844,486 Loss and loss expense incurred: Direct 1,009,819 698,994 1,763,386 1,312,223 Assumed 5,058 5,678 11,039 10,933 Ceded (89,329) (58,542) (144,585) (109,588) Net $ 925,548 646,130 $ 1,629,840 1,213,568

Reserve for Loss and Loss Exp_2

Reserve for Loss and Loss Expense (Tables)	6 Months Ended
	Jun. 30, 2024
Insurance Loss Reserves [Abstract]
Schedule of Roll Forward of Reserve for Loss and Loss Expense	The table below provides a roll forward of the reserve for loss and loss expense for beginning and ending reserve balances: Six Months ended June 30, ($ in thousands) 2024 2023 Gross reserve for loss and loss expense, at beginning of period $ 5,336,911 5,144,821 Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of period 618,601 757,513 Net reserve for loss and loss expense, at beginning of period 4,718,310 4,387,308 Incurred loss and loss expense for claims occurring in the: Current year 1,442,719 1,221,635 Prior years 187,121 (8,067) Total incurred loss and loss expense 1,629,840 1,213,568 Paid loss and loss expense for claims occurring in the: Current year 347,501 320,026 Prior years 753,658 720,314 Total paid loss and loss expense 1,101,159 1,040,340 Net reserve for loss and loss expense, at end of period 5,246,991 4,560,536 Add: Reinsurance recoverable on unpaid loss and loss expense, at end of period 656,534 616,487 Gross reserve for loss and loss expense, at end of period $ 5,903,525 5,177,023

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2024
Segment Reporting [Abstract]
Schedule of Revenue By Segment	The following summaries present revenues (net investment income and net realized and unrealized gains and losses on investments in the case of the Investments segment) and pre-tax income for the individual segments: Revenue by Segment Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Standard Commercial Lines: Net premiums earned: General liability $ 280,097 254,510 $ 553,512 497,859 Commercial automobile 260,652 225,067 512,372 442,438 Commercial property 168,511 141,348 330,064 276,640 Workers compensation 82,316 88,746 170,093 172,930 Businessowners' policies 41,641 34,385 81,562 67,556 Bonds 12,468 11,619 24,556 23,016 Other 7,808 7,034 15,444 13,885 Miscellaneous income 5,214 5,568 12,348 7,749 Total Standard Commercial Lines revenue 858,707 768,277 1,699,951 1,502,073 Standard Personal Lines: Net premiums earned: Personal automobile 57,544 48,230 114,504 93,144 Homeowners 46,055 36,902 90,168 71,915 Other 2,822 2,038 5,595 3,981 Miscellaneous income 594 536 1,235 989 Total Standard Personal Lines revenue 107,015 87,706 211,502 170,029 E&S Lines: Net premiums earned: Casualty lines 73,887 62,151 145,525 122,968 Property lines 46,430 30,120 87,780 58,154 Miscellaneous income 27 — 53 — Total E&S Lines revenue 120,344 92,271 233,358 181,122 Investments: Net investment income earned 108,642 97,696 216,491 189,202 Net realized and unrealized investment gains (losses) 1,297 (5,426) (338) (2,082) Total Investments revenue 109,939 92,270 216,153 187,120 Total revenues $ 1,196,005 1,040,524 $ 2,360,964 2,040,344
Schedule of Income (Loss) Before and After Federal Income Tax	Income (Loss) Before and After Federal Income Tax Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Standard Commercial Lines: Underwriting income (loss), before federal income tax $ (160,881) 22,146 $ (150,500) 61,067 Underwriting income (loss), after federal income tax (127,096) 17,495 (118,895) 48,243 Combined ratio 118.8 % 97.1 108.9 95.9 ROE contribution (18.4) 2.8 (8.6) 4.1 Standard Personal Lines: Underwriting income (loss), before federal income tax $ (19,301) (23,060) $ (24,636) (36,133) Underwriting income (loss), after federal income tax (15,248) (18,217) (19,462) (28,545) Combined ratio 118.1 % 126.5 111.7 121.4 ROE contribution (2.2) (2.9) (1.4) (2.4) E&S Lines: Underwriting income (loss), before federal income tax $ 6,501 (612) $ 20,486 12,723 Underwriting income (loss), after federal income tax 5,136 (483) 16,184 10,051 Combined ratio 94.6 % 100.7 91.2 93.0 ROE contribution 0.7 (0.1) 1.2 0.8 Investments: Net investment income earned $ 108,642 97,696 $ 216,491 189,202 Net realized and unrealized investment gains (losses) 1,297 (5,426) (338) (2,082) Total investments segment income, before federal income tax 109,939 92,270 216,153 187,120 Tax on investments segment income 22,652 18,745 44,518 37,901 Total investments segment income, after federal income tax $ 87,287 73,525 $ 171,635 149,219 ROE contribution of after-tax net investment income earned 12.5 12.6 12.5 12.5
Schedule of Reconciliation of Segment Results to Income (Loss) Before Federal Income Tax	Reconciliation of Segment Results to Income (Loss) Before Federal Income Tax Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Underwriting income (loss) Standard Commercial Lines $ (160,881) 22,146 $ (150,500) 61,067 Standard Personal Lines (19,301) (23,060) (24,636) (36,133) E&S Lines 6,501 (612) 20,486 12,723 Investment income 109,939 92,270 216,153 187,120 Total all segments (63,742) 90,744 61,503 224,777 Interest expense (7,202) (7,258) (14,383) (14,424) Corporate expenses (9,154) (9,329) (24,652) (21,437) Income (loss), before federal income tax $ (80,098) 74,157 $ 22,468 188,916 Preferred stock dividends (2,300) (2,300) (4,600) (4,600) Income (loss) available to common stockholders, before federal income tax $ (82,398) 71,857 $ 17,868 184,316

Retirement Plans (Table)

Retirement Plans (Table)	6 Months Ended
	Jun. 30, 2024
Retirement Benefits [Abstract]
Schedule of Components of Net Periodic Benefit Cost	The following tables provide information about the Pension Plan: Pension Plan Quarter ended June 30, Six Months ended June 30, ($ in thousands) 2024 2023 2024 2023 Net Periodic Pension Cost (Benefit): Interest cost $ 3,888 3,866 $ 7,776 7,732 Expected return on plan assets (5,383) (5,772) (10,765) (11,545) Amortization of unrecognized net actuarial loss 955 750 1,910 1,501 Total net periodic pension cost (benefit) 1 $ (540) (1,156) $ (1,079) (2,312) 1 The components of net periodic pension cost (benefit) are included within "Loss and loss expense incurred" and "Other insurance expenses" on the Consolidated Statements of Income.
Schedule of Weighted-Average Expense Assumptions	Pension Plan Six Months ended June 30, 2024 2023 Weighted-Average Expense Assumptions: Discount rate 5.02 % 5.21 % Effective interest rate for calculation of interest cost 4.91 5.09 Expected return on plan assets 6.40 6.90

Comprehensive Income (Loss) (Ta

Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2024
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Schedule of Components of Comprehensive Income-Gross and Net of Tax	The components of comprehensive income (loss), both gross and net of tax, for Second Quarter 2024 and Six Months 2024 and Second Quarter 2023 and Six Months 2023 were as follows: Second Quarter 2024 ($ in thousands) Gross Tax Net Net income (loss) $ (80,098) (16,779) (63,319) Components of OCI: Unrealized gains (losses) on investment securities : Unrealized holding gains (losses) during the period (8,347) (1,753) (6,594) Unrealized gains (losses) on securities with credit loss recognized in earnings (3,705) (778) (2,927) Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities 43 10 33 Credit loss (benefit) expense 1,233 258 975 Total unrealized gains (losses) on investment securities (10,776) (2,263) (8,513) Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 967 203 764 Total defined benefit pension and post-retirement plans 967 203 764 Other comprehensive income (loss) (9,809) (2,060) (7,749) Comprehensive income (loss) $ (89,907) (18,839) (71,068) Second Quarter 2023 ($ in thousands) Gross Tax Net Net income (loss) $ 74,157 15,549 58,608 Components of OCI: Unrealized gains (losses) on investment securities: Unrealized holding gains (losses) during the period (60,681) (12,744) (47,937) Unrealized gains (losses) on securities with credit loss recognized in earnings (6,030) (1,266) (4,764) Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities 9,383 1,970 7,413 Credit loss (benefit) expense (864) (181) (683) Total unrealized gains (losses) on investment securities (58,192) (12,221) (45,971) Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 757 159 598 Total defined benefit pension and post-retirement plans 757 159 598 Other comprehensive income (loss) (57,435) (12,062) (45,373) Comprehensive income (loss) $ 16,722 3,487 13,235 Six Months 2024 ($ in thousands) Gross Tax Net Net income (loss) $ 22,468 3,269 19,199 Components of OCI: Unrealized gains (losses) on investment securities : Unrealized holding gains (losses) during the period (23,907) (5,020) (18,887) Unrealized gains (losses) on securities with credit loss recognized in earnings (6,837) (1,436) (5,401) Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities (35) (7) (28) Credit loss (benefit) expense 3,883 815 3,068 Total unrealized gains (losses) on investment securities (26,896) (5,648) (21,248) Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 1,934 406 1,528 Total defined benefit pension and post-retirement plans 1,934 406 1,528 Other comprehensive income (loss) (24,962) (5,242) (19,720) Comprehensive income (loss) $ (2,494) (1,973) (521) Six Months 2023 ($ in thousands) Gross Tax Net Net income (loss) $ 188,916 37,734 151,182 Components of OCI: Unrealized gains (losses) on investment securities: Unrealized holding gains (losses) during the period 5,244 1,102 4,142 Unrealized gains (losses) on securities with credit loss recognized in earnings 16,401 3,444 12,957 Amounts reclassified into net income (loss): Net realized (gains) losses on disposals and intent-to-sell AFS securities 15,487 3,252 12,235 Credit loss (benefit) expense (10,393) (2,183) (8,210) Total unrealized gains (losses) on investment securities 26,739 5,615 21,124 Defined benefit pension and post-retirement plans: Amounts reclassified into net income (loss): Net actuarial (gain) loss 1,514 318 1,196 Total defined benefit pension and post-retirement plans 1,514 318 1,196 Other comprehensive income (loss) 28,253 5,933 22,320 Comprehensive income (loss) $ 217,169 43,667 173,502
Schedule of Components of Accumulated Other Comprehensive Income Net of Tax	The balances of, and changes in, each component of accumulated other comprehensive income (loss) ("AOCI") (net of taxes) as of June 30, 2024, were as follows: June 30, 2024 Net Unrealized Gains (Losses) on Investment Securities Defined Benefit Pension and Post-Retirement Plans Total AOCI ($ in thousands) Credit Loss Related 1 All Investments Balance, December 31, 2023 $ (84,442) (194,628) (279,070) (93,931) (373,001) OCI before reclassifications (5,401) (18,887) (24,288) — (24,288) Amounts reclassified from AOCI 3,068 (28) 3,040 1,528 4,568 Net current period OCI (2,333) (18,915) (21,248) 1,528 (19,720) Balance, June 30, 2024 $ (86,775) (213,543) (300,318) (92,403) (392,721) 1 Represents change in unrealized gains (losses) on securities with credit loss recognized in earnings.
Reclassifications Out of Accumulated Other Comprehensive Income	The reclassifications out of AOCI were as follows: Quarter ended June 30, Six Months ended June 30, Affected Line Item in the Unaudited Consolidated Statements of Income ($ in thousands) 2024 2023 2024 2023 Net realized (gains) losses on disposals and intent-to-sell AFS securities Net realized (gains) losses $ 43 9,383 $ (35) 15,487 Net realized and unrealized investment gains (losses) Tax (benefit) expense (10) (1,970) 7 (3,252) Total federal income tax expense (benefit) Net of taxes 33 7,413 (28) 12,235 Net income (loss) Credit loss related Credit loss (benefit) expense 1,233 (864) 3,883 (10,393) Net realized and unrealized investment gains (losses) Tax (benefit) expense (258) 181 (815) 2,183 Total federal income tax expense (benefit) Net of taxes 975 (683) 3,068 (8,210) Net income (loss) Defined benefit pension and post-retirement life plans Net actuarial loss 223 173 445 348 Loss and loss expense incurred Net actuarial loss 744 584 1,489 1,166 Other insurance expenses Total 967 757 1,934 1,514 Income (loss) before federal income tax Tax (benefit) expense (203) (159) (406) (318) Total federal income tax expense (benefit) Net of taxes 764 598 1,528 1,196 Net income (loss) Total reclassifications for the period $ 1,772 7,328 $ 4,568 5,221 Net income (loss)

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Schedule of Earnings Per Common Share, Basic and Diluted	The following table presents the calculations of earnings per common share ("EPS") on a basic and diluted basis: Quarter ended June 30, Six Months ended June 30, (in thousands, except per share amounts) 2024 2023 2024 2023 Net income (loss) available to common stockholders: $ (65,619) 56,308 $ 14,599 146,582 Weighted average common shares outstanding: Weighted average common shares outstanding - basic 60,897 60,614 60,862 60,575 Effect of dilutive securities - stock compensation plans — 323 382 343 Weighted average common shares outstanding - diluted 60,897 60,937 61,244 60,918 EPS: Basic $ (1.08) 0.93 $ 0.24 2.42 Diluted (1.08) 0.92 0.24 2.41

Statements of Cash Flows - Sche

Statements of Cash Flows - Schedule of Cash Flow Supplemental Disclosures (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Cash paid (received) during the period for:
Interest	$ 14,209	$ 14,164
Federal income tax	46,000	34,000
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	3,884	4,038
Operating cash flows from financing leases	65	20
Financing cash flows from finance leases	1,266	1,231
Non-cash items:
Assets acquired under finance lease arrangements	5,947	0
Assets acquired under operating lease arrangements	10,257	4,509
Non-cash purchase of property and equipment	9	0
Fixed income securities, AFS
Non-cash items:
Corporate actions related to securities	10,250	23,150
Equity securities
Non-cash items:
Corporate actions related to securities	$ 29,250	$ 0

Statements of Cash Flows - Sc_2

Statements of Cash Flows - Schedule of Cash and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Cash	$ 160	$ 180
Restricted cash	10,748	13,092
Total cash and restricted cash shown in the Consolidated Statements of Cash Flows	$ 10,908	$ 13,272	$ 21,258	$ 25,209

Investments - Schedule of Avail

Investments - Schedule of Available-For-Sale Securities Disclosure (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	$ 8,080,498		$ 7,880,697
Allowance for Credit Losses	(31,309)	$ (30,381)	(28,212)	$ (31,425)	$ (33,554)	$ (45,721)
Unrealized Gains	38,756		50,076
Unrealized Losses	(418,912)		(403,364)
Fair Value	7,669,033		7,499,197
U.S. government and government agencies
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	170,819		223,157
Allowance for Credit Losses	0		0
Unrealized Gains	56		139
Unrealized Losses	(19,907)		(18,261)
Fair Value	150,968		205,035
Foreign government
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	10,687		11,140
Allowance for Credit Losses	(26)	(29)	(35)	(34)	(36)	(284)
Unrealized Gains	0		0
Unrealized Losses	(1,427)		(1,302)
Fair Value	9,234		9,803
Obligations of states and political subdivisions
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	558,455		612,938
Allowance for Credit Losses	(639)	(695)	(669)	(769)	(737)	(1,024)
Unrealized Gains	770		2,623
Unrealized Losses	(33,151)		(28,927)
Fair Value	525,435		585,965
Corporate securities
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	2,987,824		2,834,048
Allowance for Credit Losses	(15,950)	(15,442)	(12,999)	(16,149)	(16,756)	(30,330)
Unrealized Gains	17,803		28,078
Unrealized Losses	(143,725)		(137,888)
Fair Value	2,845,952		2,711,239
Collateralized loan obligations ("CLO") and other asset-backed securities ("ABS")
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	1,972,687		1,911,831
Allowance for Credit Losses	(3,022)	(2,627)	(2,854)	(2,915)	(3,895)	(2,375)
Unrealized Gains	16,359		11,855
Unrealized Losses	(69,904)		(86,005)
Fair Value	1,916,120		1,834,827
Residential mortgage-backed securities ("RMBS")
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	1,624,078		1,568,960
Allowance for Credit Losses	(11,660)	(11,580)	(11,649)	(11,550)	(11,740)	(11,597)
Unrealized Gains	2,954		6,023
Unrealized Losses	(111,420)		(85,851)
Fair Value	1,503,952		1,477,483
Commercial mortgage-backed securities ("CMBS")
Debt Securities, Available-for-sale [Line Items]
Cost/ Amortized Cost	755,948		718,623
Allowance for Credit Losses	(12)	$ (8)	(6)	$ (8)	$ (390)	$ (111)
Unrealized Gains	814		1,358
Unrealized Losses	(39,378)		(45,130)
Fair Value	$ 717,372		$ 674,845

Investments - Schedule of Ava_2

Investments - Schedule of Available-for-Sale Allowance for Credit Losses Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 30,381	$ 33,554	$ 28,212	$ 45,721
Current Provision for Securities without Prior Allowance	1,135	2,128	2,828	4,894
Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration	0	0	0	0
Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities	98	(2,992)	1,055	(15,287)
Reductions for Securities Sold	(305)	(1,229)	(777)	(3,852)
Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period	0	(36)	(9)	(51)
Ending Balance	31,309	31,425	31,309	31,425
Foreign government
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning Balance	29	36	35	284
Current Provision for Securities without Prior Allowance	0	0	0	0
Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration	0	0	0	0
Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities	(3)	(2)	(3)	(250)
Reductions for Securities Sold	0	0	(6)	0
Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period	0	0	0	0
Ending Balance	26	34	26	34
Obligations of states and political subdivisions
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning Balance	695	737	669	1,024
Current Provision for Securities without Prior Allowance	18	67	37	67
Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration	0	0	0	0
Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities	(74)	(35)	(59)	(239)
Reductions for Securities Sold	0	0	(8)	(83)
Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period	0	0	0	0
Ending Balance	639	769	639	769
Corporate securities
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning Balance	15,442	16,756	12,999	30,330
Current Provision for Securities without Prior Allowance	846	1,438	2,362	4,141
Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration	0	0	0	0
Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities	(126)	(1,070)	1,166	(14,884)
Reductions for Securities Sold	(212)	(939)	(568)	(3,387)
Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period	0	(36)	(9)	(51)
Ending Balance	15,950	16,149	15,950	16,149
CLO and other ABS
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning Balance	2,627	3,895	2,854	2,375
Current Provision for Securities without Prior Allowance	271	622	427	677
Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration	0	0	0	0
Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities	126	(1,595)	(255)	(127)
Reductions for Securities Sold	(2)	(7)	(4)	(10)
Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period	0	0	0	0
Ending Balance	3,022	2,915	3,022	2,915
RMBS
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning Balance	11,580	11,740	11,649	11,597
Current Provision for Securities without Prior Allowance	0	1	0	8
Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration	0	0	0	0
Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities	171	(50)	202	174
Reductions for Securities Sold	(91)	(141)	(191)	(229)
Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period	0	0	0	0
Ending Balance	11,660	11,550	11,660	11,550
CMBS
Debt Securities, Available-for-Sale, Allowance for Credit Loss [Roll Forward]
Beginning Balance	8	390	6	111
Current Provision for Securities without Prior Allowance	0	0	2	1
Initial Allowance for Purchased Credit Deteriorated Assets with Credit Deterioration	0	0	0	0
Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities	4	(240)	4	39
Reductions for Securities Sold	0	(142)	0	(143)
Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period	0	0	0	0
Ending Balance	$ 12	$ 8	$ 12	$ 8

Investments - Accrued Investmen

Investments - Accrued Investment Income - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Accrued Investment Income [Line Items]
Accrued investment income	$ 72,305	$ 66,339
Available-for-Sale Securities
Accrued Investment Income [Line Items]
Accrued investment income	$ 70,100	$ 64,600

Investments - Schedule of Fair

Investments - Schedule of Fair Value and Gross Pre-Tax Net Unrealized Loss of Securities By Length of Time (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
U.S. government and government agencies
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	$ 33,667	$ 77,698
AFS Unrealized Losses, Less than 12 months	(52)	(188)
AFS Fair Value, 12 months or longer	107,306	108,578
AFS Unrealized Losses, 12 months or longer	(19,855)	(18,073)
AFS Fair Value	140,973	186,276
AFS Unrealized Losses	(19,907)	(18,261)
Foreign government
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	0	1,552
AFS Unrealized Losses, Less than 12 months	0	(87)
AFS Fair Value, 12 months or longer	9,234	8,251
AFS Unrealized Losses, 12 months or longer	(1,427)	(1,215)
AFS Fair Value	9,234	9,803
AFS Unrealized Losses	(1,427)	(1,302)
Obligations of states and political subdivisions
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	128,665	137,031
AFS Unrealized Losses, Less than 12 months	(1,644)	(962)
AFS Fair Value, 12 months or longer	329,528	290,964
AFS Unrealized Losses, 12 months or longer	(31,507)	(27,965)
AFS Fair Value	458,193	427,995
AFS Unrealized Losses	(33,151)	(28,927)
Corporate securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	358,779	263,423
AFS Unrealized Losses, Less than 12 months	(3,477)	(6,369)
AFS Fair Value, 12 months or longer	1,477,738	1,439,422
AFS Unrealized Losses, 12 months or longer	(140,248)	(131,519)
AFS Fair Value	1,836,517	1,702,845
AFS Unrealized Losses	(143,725)	(137,888)
CLO and other ABS
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	368,307	278,940
AFS Unrealized Losses, Less than 12 months	(6,432)	(7,120)
AFS Fair Value, 12 months or longer	798,783	984,175
AFS Unrealized Losses, 12 months or longer	(63,472)	(78,885)
AFS Fair Value	1,167,090	1,263,115
AFS Unrealized Losses	(69,904)	(86,005)
RMBS
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	385,794	351,976
AFS Unrealized Losses, Less than 12 months	(6,133)	(4,765)
AFS Fair Value, 12 months or longer	878,915	757,914
AFS Unrealized Losses, 12 months or longer	(105,287)	(81,086)
AFS Fair Value	1,264,709	1,109,890
AFS Unrealized Losses	(111,420)	(85,851)
CMBS
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	75,052	130,189
AFS Unrealized Losses, Less than 12 months	(779)	(2,995)
AFS Fair Value, 12 months or longer	550,901	471,256
AFS Unrealized Losses, 12 months or longer	(38,599)	(42,135)
AFS Fair Value	625,953	601,445
AFS Unrealized Losses	(39,378)	(45,130)
Available-for-Sale Securities
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items]
AFS Fair Value, Less than 12 Months	1,350,264	1,240,809
AFS Unrealized Losses, Less than 12 months	(18,517)	(22,486)
AFS Fair Value, 12 months or longer	4,152,405	4,060,560
AFS Unrealized Losses, 12 months or longer	(400,395)	(380,878)
AFS Fair Value	5,502,669	5,301,369
AFS Unrealized Losses	$ (418,912)	$ (403,364)

Investments - Schedule of Fixed

Investments - Schedule of Fixed Income Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
AFS, Fair Value
Due in one year or less fair value, AFS	$ 587,352
Due after one year through five years fair value, AFS	3,507,774
Due after five years through 10 years fair value, AFS	2,827,999
Due after 10 years fair value, AFS	745,908
Total AFS fixed income securities, Fair Value	7,669,033	$ 7,499,197
HTM, Carrying Value
Due in one year or less carrying value, HTM	820
Due after one year through five years carrying value, HTM	14,209
Due after five years through 10 years carrying value, HTM	4,467
Due after 10 years carrying value, HTM	0
Fixed income securities, held-to-maturity, net of allowance for credit losses	19,496	22,700
HTM, Fair Value
Due in one year or less fair value, HTM	810
Due after one year through five years fair value, HTM	13,662
Due after five years through 10 years fair value, HTM	4,084
Due after 10 years fair value, HTM	0
Total HTM fixed income securities, Fair Value	$ 18,556	$ 21,923

Investments - Schedule of Alter

Investments - Schedule of Alternative Investment Portfolio by Strategy and the Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy [Line Items]
Carrying Value	$ 414,780	$ 395,779
Private equity
Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy [Line Items]
Carrying Value	319,236	301,759
Remaining Commitment	148,558	131,885
Maximum Exposure to Loss	467,794	433,644
Private credit
Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy [Line Items]
Carrying Value	52,106	54,500
Remaining Commitment	98,417	89,401
Maximum Exposure to Loss	150,523	143,901
Real assets
Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy [Line Items]
Carrying Value	43,438	39,520
Remaining Commitment	42,336	33,040
Maximum Exposure to Loss	85,774	72,560
Total alternative investments
Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy [Line Items]
Carrying Value	414,780	395,779
Remaining Commitment	289,311	254,326
Maximum Exposure to Loss	$ 704,091	$ 650,105

Investments - Schedule of Aggre

Investments - Schedule of Aggregated Income Statement Summarized Financial Information for Partnerships in our Alternative Investment Portfolio (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 108,642	$ 97,696	$ 216,491	$ 189,202
Investments Accounted For Under The Equity Method
Schedule of Equity Method Investments [Line Items]
Net investment income (loss)	242,400	(70,600)	(103,600)	(141,300)
Realized gains	1,554,200	922,000	3,385,100	2,644,300
Net change in unrealized appreciation (depreciation)	2,850,200	3,754,000	6,669,200	5,197,800
Net income	4,646,800	4,605,400	9,950,700	7,700,800
Alternative investments
Schedule of Equity Method Investments [Line Items]
Net investment income earned	$ 10,517	$ 11,396	$ 17,398	$ 19,164

Investments -Schedule of Invest

Investments -Schedule of Investments Pledged as Collateral (Details) $ in Millions	Jun. 30, 2024 USD ($)
U.S. government and government agencies
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral on deposit with various state and regulatory agencies	$ 19.9
Securities owned and pledged as collateral, fair value	19.9
Obligations of states and political subdivisions
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral on deposit with various state and regulatory agencies	4.2
Securities owned and pledged as collateral, fair value	4.2
RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral on deposit with various state and regulatory agencies	0
Securities owned and pledged as collateral, fair value	87.4
CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral on deposit with various state and regulatory agencies	0
Securities owned and pledged as collateral, fair value	10.4
Total pledged as collateral
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral on deposit with various state and regulatory agencies	24.1
Securities owned and pledged as collateral, fair value	121.9
Federal Home Loan Bank of Indianapolis | U.S. government and government agencies
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	0
Federal Home Loan Bank of Indianapolis | Obligations of states and political subdivisions
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	0
Federal Home Loan Bank of Indianapolis | RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	64.2
Federal Home Loan Bank of Indianapolis | CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	2.1
Federal Home Loan Bank of Indianapolis | Total pledged as collateral
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	66.3
Federal Home Loan Bank of New York | U.S. government and government agencies
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	0
Federal Home Loan Bank of New York | Obligations of states and political subdivisions
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	0
Federal Home Loan Bank of New York | RMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	23.2
Federal Home Loan Bank of New York | CMBS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	8.3
Federal Home Loan Bank of New York | Total pledged as collateral
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities pledged as collateral with FHLB	$ 31.5

Investments - Credit Concentrat

Investments - Credit Concentration Risk (Details)	Jun. 30, 2024	Dec. 31, 2023
Investments [Abstract]
Maximum exposure to credit concentration risk of a single issuer of the Company's stockholder's equity, other than to certain U.S. government-backed investments	10%	10%

Investments -Schedule of Net In

Investments -Schedule of Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net Investment Income [Line Items]
Net investment income earned	$ 108,642	$ 97,696	$ 216,491	$ 189,202
Fixed income securities
Net Investment Income [Line Items]
Net investment income earned	93,935	83,916	188,037	164,003
Commercial mortgage loans ("CMLs")
Net Investment Income [Line Items]
Net investment income earned	3,145	2,199	5,939	4,164
Equity securities
Net Investment Income [Line Items]
Net investment income earned	1,877	2,236	6,785	3,441
Short-term investments
Net Investment Income [Line Items]
Net investment income earned	4,680	2,892	8,199	7,542
Alternative investments
Net Investment Income [Line Items]
Net investment income earned	10,517	11,396	17,398	19,164
Other investments
Net Investment Income [Line Items]
Net investment income earned	118	188	381	231
Investment expenses
Net Investment Income [Line Items]
Investment expenses	$ (5,630)	$ (5,131)	$ (10,248)	$ (9,343)

Investments - Schedule of Net R

Investments - Schedule of Net Realized and Unrealized Investment Gains and (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Gain (Loss) on Securities [Line Items]
Gross gains on sales	$ 4,387	$ 1,156	$ 6,522	$ 4,940
Gross losses on sales	(1,251)	(11,952)	(3,216)	(24,882)
Net realized gains (losses) on disposals	3,136	(10,796)	3,306	(19,942)
Net unrealized gains (losses) on equity securities	(93)	4,925	599	8,173
Losses on securities for which we have the intent to sell	(481)	(341)	(496)	(645)
Net realized and unrealized investment gains (losses)	1,297	(5,426)	(338)	(2,082)
Available-for-Sale Securities
Gain (Loss) on Securities [Line Items]
Net credit loss benefit (expense)	(1,233)	864	(3,883)	10,393
Commercial mortgage loans ("CMLs")
Gain (Loss) on Securities [Line Items]
Net credit loss benefit (expense)	$ (32)	$ (78)	$ 136	$ (61)

Investments - Schedule of Reali

Investments - Schedule of Realized and Unrealized Gains (Losses) on Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Investments [Abstract]
Unrealized gains (losses) recognized in income on equity securities remaining in our portfolio at end of period	$ 2,617	$ 2,784	$ 2,906	$ 2,685
Unrealized gains (losses) recognized in income on equity securities sold in period	(2,710)	2,141	(2,307)	5,488
Total unrealized gains (losses) recognized in income on equity securities	$ (93)	$ 4,925	$ 599	$ 8,173

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Carrying Values and Estimated Fair Values of Financial Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 508,801	$ 503,946
Long-term debt, fair value	491,369	503,805
Finance lease obligations	$ 7,318	$ 2,636
7.25% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	7.25%	7.25%
Long-term debt, fair value	$ 51,301	$ 53,047
7.25% Senior Notes | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 49,928	$ 49,926
6.70% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	6.70%	6.70%
Long-term debt, fair value	$ 99,393	$ 104,039
6.70% Senior Notes | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 99,577	$ 99,565
5.375% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	5.375%	5.375%
Long-term debt, fair value	$ 283,037	$ 288,787
5.375% Senior Notes | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 294,574	$ 294,523
3.03% borrowings from FHLBI
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	3.03%	3.03%
Long-term debt, fair value	$ 57,638	$ 57,932
3.03% borrowings from FHLBI | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	60,000	60,000
Subtotal long-term debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	491,369	503,805
Subtotal long-term debt | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	504,079	504,014
Unamortized debt issuance costs | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unamortized debt issuance costs	$ (2,596)	$ (2,704)

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Disclosures of Fair Value Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
AFS fixed income securities	$ 7,669,033	$ 7,499,197
Equity securities	191,964	187,155
Short-term investments	417,346	309,317
Fair Value, Recurring
AFS fixed income securities	7,669,033	7,499,197
Equity securities	191,964	187,155
Short-term investments	417,346	309,317
Total assets measured at fair value	8,278,343	7,995,669
U.S. government and government agencies
AFS fixed income securities	150,968	205,035
U.S. government and government agencies | Fair Value, Recurring
AFS fixed income securities	150,968	205,035
Foreign government
AFS fixed income securities	9,234	9,803
Foreign government | Fair Value, Recurring
AFS fixed income securities	9,234	9,803
Obligations of states and political subdivisions
AFS fixed income securities	525,435	585,965
Obligations of states and political subdivisions | Fair Value, Recurring
AFS fixed income securities	525,435	585,965
Corporate securities
AFS fixed income securities	2,845,952	2,711,239
Corporate securities | Fair Value, Recurring
AFS fixed income securities	2,845,952	2,711,239
CLO and other ABS
AFS fixed income securities	1,916,120	1,834,827
CLO and other ABS | Fair Value, Recurring
AFS fixed income securities	1,916,120	1,834,827
RMBS
AFS fixed income securities	1,503,952	1,477,483
RMBS | Fair Value, Recurring
AFS fixed income securities	1,503,952	1,477,483
CMBS
AFS fixed income securities	717,372	674,845
CMBS | Fair Value, Recurring
AFS fixed income securities	717,372	674,845
Common stock | Fair Value, Recurring
Equity securities	190,141	185,339
Preferred stock | Fair Value, Recurring
Equity securities	1,823	1,816
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | Fair Value, Recurring
AFS fixed income securities	33,453	34,056
Equity securities	36,638	22,398
Short-term investments	400,906	308,512
Total assets measured at fair value	470,997	364,966
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | U.S. government and government agencies | Fair Value, Recurring
AFS fixed income securities	33,453	34,056
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | Foreign government | Fair Value, Recurring
AFS fixed income securities	0	0
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | Obligations of states and political subdivisions | Fair Value, Recurring
AFS fixed income securities	0	0
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | Corporate securities | Fair Value, Recurring
AFS fixed income securities	0	0
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | CLO and other ABS | Fair Value, Recurring
AFS fixed income securities	0	0
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | RMBS | Fair Value, Recurring
AFS fixed income securities	0	0
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | CMBS | Fair Value, Recurring
AFS fixed income securities	0	0
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | Common stock | Fair Value, Recurring
Equity securities	34,815	20,582
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | Preferred stock | Fair Value, Recurring
Equity securities	1,823	1,816
Significant Other Observable Inputs (Level 2) | Fair Value, Recurring
AFS fixed income securities	7,065,258	6,914,306
Equity securities	0	0
Short-term investments	16,440	805
Total assets measured at fair value	7,081,698	6,915,111
Significant Other Observable Inputs (Level 2) | U.S. government and government agencies | Fair Value, Recurring
AFS fixed income securities	117,515	170,979
Significant Other Observable Inputs (Level 2) | Foreign government | Fair Value, Recurring
AFS fixed income securities	9,234	9,803
Significant Other Observable Inputs (Level 2) | Obligations of states and political subdivisions | Fair Value, Recurring
AFS fixed income securities	517,781	578,131
Significant Other Observable Inputs (Level 2) | Corporate securities | Fair Value, Recurring
AFS fixed income securities	2,552,239	2,413,907
Significant Other Observable Inputs (Level 2) | CLO and other ABS | Fair Value, Recurring
AFS fixed income securities	1,652,400	1,589,514
Significant Other Observable Inputs (Level 2) | RMBS | Fair Value, Recurring
AFS fixed income securities	1,499,066	1,477,483
Significant Other Observable Inputs (Level 2) | CMBS | Fair Value, Recurring
AFS fixed income securities	717,023	674,489
Significant Other Observable Inputs (Level 2) | Common stock | Fair Value, Recurring
Equity securities	0	0
Significant Other Observable Inputs (Level 2) | Preferred stock | Fair Value, Recurring
Equity securities	0	0
Significant Unobservable Inputs (Level 3) | Fair Value, Recurring
AFS fixed income securities	570,322	550,835
Equity securities	1,067	854
Short-term investments	0	0
Total assets measured at fair value	571,389	551,689
Significant Unobservable Inputs (Level 3) | U.S. government and government agencies | Fair Value, Recurring
AFS fixed income securities	0	0
Significant Unobservable Inputs (Level 3) | Foreign government | Fair Value, Recurring
AFS fixed income securities	0	0
Significant Unobservable Inputs (Level 3) | Obligations of states and political subdivisions | Fair Value, Recurring
AFS fixed income securities	7,654	7,834
Significant Unobservable Inputs (Level 3) | Corporate securities | Fair Value, Recurring
AFS fixed income securities	293,713	297,332
Significant Unobservable Inputs (Level 3) | CLO and other ABS | Fair Value, Recurring
AFS fixed income securities	263,720	245,313
Significant Unobservable Inputs (Level 3) | RMBS | Fair Value, Recurring
AFS fixed income securities	4,886	0
Significant Unobservable Inputs (Level 3) | CMBS | Fair Value, Recurring
AFS fixed income securities	349	356
Significant Unobservable Inputs (Level 3) | Common stock | Fair Value, Recurring
Equity securities	1,067	854
Significant Unobservable Inputs (Level 3) | Preferred stock | Fair Value, Recurring
Equity securities	0	0
Fair Value Measured at Net Asset Value Per Share
Equity securities	$ 154,300	$ 163,900

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Changes in Fair Value of Securities Using Level 3 Inputs (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 551,689
Fair value, ending balance	571,389
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	551,689	$ 349,255
Purchases	40,266	98,299
Sales	0	0
Issuances	0	0
Settlements	(12,067)	(8,709)
Transfers into Level 3	48,433	19,234
Transfers out of Level 3	(58,958)	(3,579)
Fair value, ending balance	571,389	455,170
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	478	95
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	1,705	735
Investments | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	470	95
Investments | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(502)	(171)
Investments | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	2,058	746
Obligations of states and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	7,834	6,661
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(68)	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair value, ending balance	7,654	6,716
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	0	62
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	(112)	(7)
Obligations of states and political subdivisions | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	62
Obligations of states and political subdivisions | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	0
Obligations of states and political subdivisions | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	(112)	(7)
Corporate securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	297,332	187,980
Purchases	5,261	58,586
Sales	0	0
Issuances	0	0
Settlements	(7,269)	(5,535)
Transfers into Level 3	28,896	2,238
Transfers out of Level 3	(31,434)	0
Fair value, ending balance	293,713	245,489
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	226	251
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	850	1,846
Corporate securities | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	218	251
Corporate securities | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(494)	112
Corporate securities | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	1,203	1,857
CLO and other ABS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	245,313	153,342
Purchases	30,119	39,713
Sales	0	0
Issuances	0	0
Settlements	(4,726)	(3,153)
Transfers into Level 3	19,537	14,148
Transfers out of Level 3	(27,524)	(953)
Fair value, ending balance	263,720	201,926
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	39	17
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	969	(1,168)
CLO and other ABS | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	39	17
CLO and other ABS | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(7)	(20)
CLO and other ABS | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	969	(1,168)
RMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	0
Purchases	4,886
Sales	0
Issuances	0
Settlements	0
Transfers into Level 3	0
Transfers out of Level 3	0
Fair value, ending balance	4,886
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	0
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	0
RMBS | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0
RMBS | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0
RMBS | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	0
CMBS
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	356	375
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	(4)	(21)
Transfers into Level 3	0	2,848
Transfers out of Level 3	0	(2,626)
Fair value, ending balance	349	377
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	0	0
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	(2)	64
CMBS | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	0
CMBS | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	(1)	(263)
CMBS | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	(2)	64
Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	854	897
Purchases	0	0
Sales	0	0
Issuances	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Fair value, ending balance	1,067	662
Change in unrealized gains (losses) for the period included in earnings for assets held at period end	213	(235)
Change in unrealized gains (losses) for the period included in OCI for assets held at period end	0	0
Common stock | Net realized and unrealized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	213	(235)
Common stock | Net investment income earned
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in net income	0	0
Common stock | Other Comprehensive Income (Loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total net gains (losses) for the period included in OCI	$ 0	$ 0

Fair Value Measurements - Sch_3

Fair Value Measurements - Schedule of Quantitative Information about Significant Unobservable Inputs in the Fair Value Measurement of Level 3 Assets (Details) $ in Thousands	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investment assets measured at fair value	$ 258,654	$ 288,955
Total Level 3 securities	571,389	551,689
Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Level 3 securities	293,713	297,332	$ 245,489	$ 187,980
CLO and other ABS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Level 3 securities	263,720	245,313	$ 201,926	$ 153,342
Valuation Technique, Discounted Cash Flow
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	312,735	262,734
Valuation Technique, Discounted Cash Flow | Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	154,075	135,524
Valuation Technique, Discounted Cash Flow | CLO and other ABS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	$ 158,660	$ 127,210
Valuation Technique, Discounted Cash Flow | Illiquidity Spread | Minimum | Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	(0.044)	(0.044)
Valuation Technique, Discounted Cash Flow | Illiquidity Spread | Minimum | CLO and other ABS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.0001	0.0001
Valuation Technique, Discounted Cash Flow | Illiquidity Spread | Maximum | Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.053	0.053
Valuation Technique, Discounted Cash Flow | Illiquidity Spread | Maximum | CLO and other ABS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.196	0.196
Valuation Technique, Discounted Cash Flow | Illiquidity Spread | Weighted Average | Corporate securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.018	0.019
Valuation Technique, Discounted Cash Flow | Illiquidity Spread | Weighted Average | CLO and other ABS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities, available-for-sale, measurement input	0.025	0.024

Fair Value Measurements - Sch_4

Fair Value Measurements - Schedule of Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	$ 18,556	$ 21,923
Commercial mortgage loans, fair value	209,041	178,913
Long-term debt, fair value	491,369	503,805
Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	18,556	21,923
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	0	0
Commercial mortgage loans, fair value	0	0
Long-term debt, fair value	0	0
Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1) | Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	18,556	21,923
Commercial mortgage loans, fair value	0	0
Long-term debt, fair value	491,369	503,805
Significant Other Observable Inputs (Level 2) | Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	18,556	21,923
Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	0	0
Commercial mortgage loans, fair value	209,041	178,913
Long-term debt, fair value	0	0
Significant Unobservable Inputs (Level 3) | Corporate securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fixed income securities, held-to-maturity - fair value	$ 0	$ 0
7.25% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	7.25%	7.25%
Long-term debt, fair value	$ 51,301	$ 53,047
7.25% Senior Notes | Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
7.25% Senior Notes | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	51,301	53,047
7.25% Senior Notes | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 0	$ 0
6.70% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	6.70%	6.70%
Long-term debt, fair value	$ 99,393	$ 104,039
6.70% Senior Notes | Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
6.70% Senior Notes | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	99,393	104,039
6.70% Senior Notes | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 0	$ 0
5.375% Senior Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	5.375%	5.375%
Long-term debt, fair value	$ 283,037	$ 288,787
5.375% Senior Notes | Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
5.375% Senior Notes | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	283,037	288,787
5.375% Senior Notes | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 0	$ 0
3.03% borrowings from FHLBI
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate	3.03%	3.03%
Long-term debt, fair value	$ 57,638	$ 57,932
3.03% borrowings from FHLBI | Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
3.03% borrowings from FHLBI | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	57,638	57,932
3.03% borrowings from FHLBI | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	$ 0	$ 0

Allowance for Credit Losses o_3

Allowance for Credit Losses on Premiums Receivable (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 20,000	$ 17,100	$ 18,900	$ 16,100
Current period change for expected credit losses	2,488	1,515	4,272	3,425
Write-offs charged against the allowance for credit losses	(1,720)	(1,047)	(2,776)	(2,211)
Recoveries	332	332	704	586
Allowance for credit losses, end of period	$ 21,100	$ 17,900	$ 21,100	$ 17,900

Reinsurance - Schedule of Disag

Reinsurance - Schedule of Disaggregation of Reinsurance Recoverable by Financial Strength Rating and Aging Analysis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	$ 687,288		$ 658,525
Less: allowance for credit losses	(1,700)	$ (1,700)	(1,700)	$ (1,800)	$ (2,300)	$ (1,600)
Total reinsurance recoverable, net	685,588		656,825
Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments, Gross | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	684,686		654,071
Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments, Gross | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	2,602		4,454
Federal and state pools
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	83,241		80,506
Federal and state pools | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	83,241		80,506
Federal and state pools | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	0		0
Other than federal and state pools
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	3,948		4,565
Other than federal and state pools | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	3,785		4,488
Other than federal and state pools | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	163		77
Total non-rated reinsurers
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	87,189		85,071
Total non-rated reinsurers | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	87,026		84,994
Total non-rated reinsurers | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	163		77
A++
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	84,615		82,487
A++ | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	83,944		82,466
A++ | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	671		21
A+
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	392,660		374,019
A+ | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	392,094		371,132
A+ | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	566		2,887
A
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	117,744		113,263
A | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	116,631		111,883
A | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	1,113		1,380
A-
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	5,080		3,685
A- | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	4,991		3,596
A- | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	89		89
Total rated reinsurers
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	600,099		573,454
Total rated reinsurers | Current
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	597,660		569,077
Total rated reinsurers | Past Due
Reinsurance Recoverable, Credit Quality Indicator [Line Items]
Total reinsurance recoverable, gross	$ 2,439		$ 4,377

Reinsurance - Schedule of Allow

Reinsurance - Schedule of Allowance for Credit Losses on Reinsurance Recoverable (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Reinsurance Recoverable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 1,700	$ 2,300	$ 1,700	$ 1,600
Current period change for expected credit losses	0	(500)	0	200
Write-offs charged against the allowance for credit losses	0	0	0	0
Recoveries	0	0	0	0
Allowance for credit losses, end of period	$ 1,700	$ 1,800	$ 1,700	$ 1,800

Reinsurance - Schedule of Direc

Reinsurance - Schedule of Direct, Assumed, and Ceded Reinsurance Amounts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Premiums written:
Direct	$ 1,399,738	$ 1,232,496	$ 2,715,649	$ 2,365,256
Assumed	6,413	5,577	12,398	10,971
Ceded	(180,050)	(153,166)	(345,325)	(291,552)
Net	1,226,101	1,084,907	2,382,722	2,084,675
Premiums earned:
Direct	1,242,696	1,073,498	2,448,064	2,105,726
Assumed	5,779	5,968	11,970	12,258
Ceded	(168,244)	(137,316)	(328,859)	(273,498)
Net	1,080,231	942,150	2,131,175	1,844,486
Loss and loss expense incurred:
Direct	1,009,819	698,994	1,763,386	1,312,223
Assumed	5,058	5,678	11,039	10,933
Ceded	(89,329)	(58,542)	(144,585)	(109,588)
Net	$ 925,548	$ 646,130	$ 1,629,840	$ 1,213,568

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Effects of Reinsurance [Line Items]
Effect in direct loss and loss expense incurred			$ 187,121	$ (8,067)
Casualty lines
Effects of Reinsurance [Line Items]
Effect in direct loss and loss expense incurred	$ 176,000	$ (3,500)	$ 211,000	$ (16,500)

Reserve for Loss and Loss Exp_3

Reserve for Loss and Loss Expense - Schedule of Rollforward of Reserve for Loss and Loss Expense (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserve for loss and loss expense, at beginning of period	$ 5,336,911	$ 5,144,821
Less: reinsurance recoverable on unpaid loss and loss expense, at beginning of period	618,601	757,513
Net reserve for loss and loss expense, at beginning of period	4,718,310	4,387,308
Incurred loss and loss expense for claims occurring in the:
Current year	1,442,719	1,221,635
Prior years	187,121	(8,067)
Total incurred loss and loss expense	1,629,840	1,213,568
Paid loss and loss expense for claims occurring in the:
Current year	347,501	320,026
Prior years	753,658	720,314
Total paid loss and loss expense	1,101,159	1,040,340
Net reserve for loss and loss expense, at end of period	5,246,991	4,560,536
Add: Reinsurance recoverable on unpaid loss and loss expense, at end of period	656,534	616,487
Gross reserve for loss and loss expense, at end of period	$ 5,903,525	$ 5,177,023

Reserve for Loss and Loss Exp_4

Reserve for Loss and Loss Expense - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year			$ 187,121	$ (8,067)
Casualty reserve
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year	$ 176,000	$ (3,500)	211,000	(16,500)
Casualty reserve | Workers' compensation
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year			(15,000)	(17,500)
Casualty reserve | E&S
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year				(5,000)
Casualty reserve | Personal automobile
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year			5,000	6,000
Casualty reserve | Standard Commercial Lines | General liability
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year			216,000
Casualty reserve | Standard Commercial Lines | Commercial automobile
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year			10,000
Casualty reserve | Standard Personal Lines | Homeowners
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year			(5,000)
Property reserve
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Incurred loss and loss expense for claims occurring in the prior year			$ (23,900)	$ 8,400

Segment Information - Narrative

Segment Information - Narrative (Details)	6 Months Ended
	Jun. 30, 2024 segment
Segment Reporting [Abstract]
Number of reportable segments	4

Segment Information - Schedule

Segment Information - Schedule of Revenue by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Net premiums earned:	$ 1,080,231	$ 942,150	$ 2,131,175	$ 1,844,486
Miscellaneous income	5,835	6,104	13,636	8,738
Net investment income earned	108,642	97,696	216,491	189,202
Net realized and unrealized investment gains (losses)	1,297	(5,426)	(338)	(2,082)
Total Investments revenue	109,939	92,270	216,153	187,120
Total revenues	1,196,005	1,040,524	2,360,964	2,040,344
Standard Commercial Lines
Segment Reporting Information [Line Items]
Total revenues	858,707	768,277	1,699,951	1,502,073
Standard Commercial Lines | General liability
Segment Reporting Information [Line Items]
Net premiums earned:	280,097	254,510	553,512	497,859
Standard Commercial Lines | Commercial automobile
Segment Reporting Information [Line Items]
Net premiums earned:	260,652	225,067	512,372	442,438
Standard Commercial Lines | Commercial property
Segment Reporting Information [Line Items]
Net premiums earned:	168,511	141,348	330,064	276,640
Standard Commercial Lines | Workers compensation
Segment Reporting Information [Line Items]
Net premiums earned:	82,316	88,746	170,093	172,930
Standard Commercial Lines | Businessowners' policies
Segment Reporting Information [Line Items]
Net premiums earned:	41,641	34,385	81,562	67,556
Standard Commercial Lines | Bonds
Segment Reporting Information [Line Items]
Net premiums earned:	12,468	11,619	24,556	23,016
Standard Commercial Lines | Other
Segment Reporting Information [Line Items]
Net premiums earned:	7,808	7,034	15,444	13,885
Standard Commercial Lines | Miscellaneous income
Segment Reporting Information [Line Items]
Miscellaneous income	5,214	5,568	12,348	7,749
Standard Personal Lines
Segment Reporting Information [Line Items]
Total revenues	107,015	87,706	211,502	170,029
Standard Personal Lines | Miscellaneous income
Segment Reporting Information [Line Items]
Miscellaneous income	594	536	1,235	989
Standard Personal Lines | Personal automobile
Segment Reporting Information [Line Items]
Net premiums earned:	57,544	48,230	114,504	93,144
Standard Personal Lines | Homeowners
Segment Reporting Information [Line Items]
Net premiums earned:	46,055	36,902	90,168	71,915
Standard Personal Lines | Other
Segment Reporting Information [Line Items]
Net premiums earned:	2,822	2,038	5,595	3,981
E&S Lines
Segment Reporting Information [Line Items]
Total revenues	120,344	92,271	233,358	181,122
E&S Lines | Miscellaneous income
Segment Reporting Information [Line Items]
Miscellaneous income	27	0	53	0
E&S Lines | Casualty lines
Segment Reporting Information [Line Items]
Net premiums earned:	73,887	62,151	145,525	122,968
E&S Lines | Property lines
Segment Reporting Information [Line Items]
Net premiums earned:	$ 46,430	$ 30,120	$ 87,780	$ 58,154

Segment Information - Schedul_2

Segment Information - Schedule of Income (Loss) Before and After Federal Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Net investment income earned	$ 108,642	$ 97,696	$ 216,491	$ 189,202
Net realized and unrealized investment gains (losses)	1,297	(5,426)	(338)	(2,082)
Total investments segment income, before federal income tax	109,939	92,270	216,153	187,120
Tax on investments segment income	22,652	18,745	44,518	37,901
Total investments segment income, after federal income tax	87,287	73,525	171,635	149,219
Standard Commercial Lines
Segment Reporting Information [Line Items]
Underwriting income (loss), before federal income tax	(160,881)	22,146	(150,500)	61,067
Underwriting income (loss), after federal income tax	$ (127,096)	$ 17,495	$ (118,895)	$ 48,243
Combined ratio	118.80%	97.10%	108.90%	95.90%
ROE contribution	(18.40%)	2.80%	(8.60%)	4.10%
Standard Personal Lines
Segment Reporting Information [Line Items]
Underwriting income (loss), before federal income tax	$ (19,301)	$ (23,060)	$ (24,636)	$ (36,133)
Underwriting income (loss), after federal income tax	$ (15,248)	$ (18,217)	$ (19,462)	$ (28,545)
Combined ratio	118.10%	126.50%	111.70%	121.40%
ROE contribution	(2.20%)	(2.90%)	(1.40%)	(2.40%)
E&S Lines
Segment Reporting Information [Line Items]
Underwriting income (loss), before federal income tax	$ 6,501	$ (612)	$ 20,486	$ 12,723
Underwriting income (loss), after federal income tax	$ 5,136	$ (483)	$ 16,184	$ 10,051
Combined ratio	94.60%	100.70%	91.20%	93%
ROE contribution	0.70%	(0.10%)	1.20%	0.80%
Investments
Segment Reporting Information [Line Items]
ROE contribution	12.50%	12.60%	12.50%	12.50%
Total investments segment income, before federal income tax	$ 109,939	$ 92,270	$ 216,153	$ 187,120

Segment Information - Schedul_3

Segment Information - Schedule of Reconciliation of Segment Results to Income (Loss) Before Federal Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Investment income	$ 109,939	$ 92,270	$ 216,153	$ 187,120
Interest expense	(7,202)	(7,258)	(14,383)	(14,424)
Corporate expenses	(9,154)	(9,329)	(24,652)	(21,437)
Income (loss), before federal income tax	(80,098)	74,157	22,468	188,916
Preferred stock dividends	(2,300)	(2,300)	(4,600)	(4,600)
Income (loss) available to common stockholders, before federal income tax	(82,398)	71,857	17,868	184,316
Standard Commercial Lines
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting income (loss)	(160,881)	22,146	(150,500)	61,067
Standard Personal Lines
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting income (loss)	(19,301)	(23,060)	(24,636)	(36,133)
E&S Lines
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Underwriting income (loss)	6,501	(612)	20,486	12,723
Investments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Investment income	109,939	92,270	216,153	187,120
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total all segments	$ (63,742)	$ 90,744	$ 61,503	$ 224,777

Retirement Plans - Schedule of

Retirement Plans - Schedule of Components of Net Periodic Benefit Cost (Details) - Defined benefit pension plan - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	$ 3,888	$ 3,866	$ 7,776	$ 7,732
Expected return on plan assets	(5,383)	(5,772)	(10,765)	(11,545)
Amortization of unrecognized net actuarial loss	955	750	1,910	1,501
Total net periodic pension cost (benefit)	$ (540)	$ (1,156)	$ (1,079)	$ (2,312)

Retirement Plans - Schedule o_2

Retirement Plans - Schedule of Weighted-Average Expense Assumptions (Details) - Defined benefit pension plan	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Discount rate	5.02%	5.21%
Effective interest rate for calculation of interest cost	4.91%	5.09%
Expected return on plan assets	6.40%	6.90%

Comprehensive Income (Loss) - S

Comprehensive Income (Loss) - Schedule of Components of Comprehensive Income-Gross and Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income (loss), Gross	$ (80,098)	$ 74,157	$ 22,468	$ 188,916
Unrealized holding gains (losses) during the period, Gross	(8,347)	(60,681)	(23,907)	5,244
Unrealized gains (losses) on securities with credit loss recognized in earnings, Gross	(3,705)	(6,030)	(6,837)	16,401
Amounts reclassified into net income (loss): net realized (gains) losses on disposals and intent-to-sell AFS securities, Gross	43	9,383	(35)	15,487
Amounts reclassified into net income (loss): Credit loss (benefit) expense, Gross	1,233	(864)	3,883	(10,393)
Total unrealized gains (losses) on investment securities, Gross	(10,776)	(58,192)	(26,896)	26,739
Amount reclassified into net income (loss): Net actuarial (gain) loss, Gross	967	757	1,934	1,514
Total defined benefit pension and post-retirement plans, Gross	967	757	1,934	1,514
Other comprehensive income (loss), Gross	(9,809)	(57,435)	(24,962)	28,253
Comprehensive income (loss), Gross	(89,907)	16,722	(2,494)	217,169
Net income (loss), Tax	(16,779)	15,549	3,269	37,734
Unrealized holding gains (losses) during the period, Tax	(1,753)	(12,744)	(5,020)	1,102
Unrealized gains (losses) on securities with credit loss recognized in earnings, Tax	(778)	(1,266)	(1,436)	3,444
Amounts reclassified into net income (loss): net realized (gains) losses on disposals and intent-to-sell AFS securities, Tax	10	1,970	(7)	3,252
Amounts reclassified into net income (loss): Credit loss (benefit) expense, Tax	258	(181)	815	(2,183)
Total unrealized gains (losses) on investment securities, Tax	(2,263)	(12,221)	(5,648)	5,615
Amount reclassified into net income (loss): Net actuarial (gain) loss, Tax	203	159	406	318
Total defined benefit pension and post-retirement plans, Tax	203	159	406	318
Other comprehensive income (loss), Tax	(2,060)	(12,062)	(5,242)	5,933
Comprehensive income (loss), Tax	(18,839)	3,487	(1,973)	43,667
Net income (loss)	(63,319)	58,608	19,199	151,182
Unrealized holding gains (losses) during the period, Net	(6,594)	(47,937)	(18,887)	4,142
Unrealized gains (losses) on securities with credit loss recognized in earnings, Net	(2,927)	(4,764)	(5,401)	12,957
Amounts reclassified into net income (loss): net realized (gains) losses on disposals and intent-to-sell AFS securities, Net	33	7,413	(28)	12,235
Amounts reclassified into net income (loss): Credit loss (benefit) expense, Net	975	(683)	3,068	(8,210)
Total unrealized gains (losses) on investment securities	(8,513)	(45,971)	(21,248)	21,124
Amount reclassified into net income (loss): Net actuarial (gain) loss, Net	764	598	1,528	1,196
Total defined benefit pension and post-retirement plans	764	598	1,528	1,196
Other comprehensive income (loss)	(7,749)	(45,373)	(19,720)	22,320
Comprehensive income (loss)	$ (71,068)	$ 13,235	$ (521)	$ 173,502

Comprehensive Income (Loss) -_2

Comprehensive Income (Loss) - Schedule of Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2023			$ (373,001)
Net current period OCI	$ (7,749)	$ (45,373)	(19,720)	$ 22,320
Balance, June 30, 2024	(392,721)		(392,721)
Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2023			(194,628)
OCI before reclassifications			(18,887)
Amounts reclassified from AOCI			(28)
Net current period OCI			(18,915)
Balance, June 30, 2024	(213,543)		(213,543)
Investments Subtotal
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2023			(279,070)
OCI before reclassifications			(24,288)
Amounts reclassified from AOCI			3,040
Net current period OCI			(21,248)
Balance, June 30, 2024	(300,318)		(300,318)
Credit Loss Related
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2023			(84,442)
OCI before reclassifications			(5,401)
Amounts reclassified from AOCI			3,068
Net current period OCI			(2,333)
Balance, June 30, 2024	(86,775)		(86,775)
Defined benefit pension and post-retirement life plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2023			(93,931)
OCI before reclassifications			0
Amounts reclassified from AOCI			1,528
Net current period OCI			1,528
Balance, June 30, 2024	(92,403)		(92,403)
Total AOCI
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2023			(373,001)
OCI before reclassifications			(24,288)
Amounts reclassified from AOCI			4,568
Net current period OCI	(7,749)	$ (45,373)	(19,720)	$ 22,320
Balance, June 30, 2024	$ (392,721)		$ (392,721)

Comprehensive Income (Loss) -_3

Comprehensive Income (Loss) - Schedule of Reclassification out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Net realized and unrealized investment gains (losses)	$ 1,297	$ (5,426)	$ (338)	$ (2,082)
Total federal income tax expense (benefit)	16,779	(15,549)	(3,269)	(37,734)
Loss and loss expense incurred	925,548	646,130	1,629,840	1,213,568
Other insurance expenses	107,773	108,857	223,760	217,445
Income (loss), before federal income tax	(80,098)	74,157	22,468	188,916
Net income (loss)	(63,319)	58,608	19,199	151,182
Reclassification out of AOCI
Net income (loss)	1,772	7,328	4,568	5,221
Reclassification out of AOCI | Defined benefit pension plan
Total federal income tax expense (benefit)	(203)	(159)	(406)	(318)
Loss and loss expense incurred	223	173	445	348
Other insurance expenses	744	584	1,489	1,166
Income (loss), before federal income tax	967	757	1,934	1,514
Net income (loss)	764	598	1,528	1,196
Reclassification out of AOCI | Net realized (gains) losses on disposals and intent-to-sell AFS securities
Net realized and unrealized investment gains (losses)	43	9,383	(35)	15,487
Total federal income tax expense (benefit)	(10)	(1,970)	7	(3,252)
Net income (loss)	33	7,413	(28)	12,235
Reclassification out of AOCI | Credit loss related
Net realized and unrealized investment gains (losses)	1,233	(864)	3,883	(10,393)
Total federal income tax expense (benefit)	(258)	181	(815)	2,183
Net income (loss)	$ 975	$ (683)	$ 3,068	$ (8,210)

Earnings per Common Share (Deta

Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net income (loss) available to common stockholders:	$ (65,619)	$ 56,308	$ 14,599	$ 146,582
Weighted average common shares outstanding:
Weighted average common shares outstanding - basic (in shares)	60,897	60,614	60,862	60,575
Effect of dilutive securities - stock compensation plans (in shares)	0	323	382	343
Weighted average common shares outstanding - diluted (in shares)	60,897	60,937	61,244	60,918
EPS:
Basic (in dollars per share)	$ (1.08)	$ 0.93	$ 0.24	$ 2.42
Diluted (in dollars per share)	$ (1.08)	$ 0.92	$ 0.24	$ 2.41
Antidilutive securities excluded from computation of earnings per share, amount	400

Litigation (Details)

Litigation (Details)	Jun. 30, 2024 subsidiary
Commitments and Contingencies Disclosure [Abstract]
Number of insurance subsidiaries	10