Hamilton Insurance (HG) 10-Q 7 Nov 24 2024 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2024	Oct. 31, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-41862
Entity Registrant Name	Hamilton Insurance Group, Ltd.
Entity Incorporation, State or Country Code	D0
Entity Tax Identification Number	98-1153847
Entity Address, Address Line One	Wellesley House North, 1st Floor
Entity Address, Address Line Two	90 Pitts Bay Road
Entity Address, City or Town	Pembroke
Entity Address, Postal Zip Code	HM 08
Entity Address, Country	BM
City Area Code	441
Local Phone Number	405-5200
Title of 12(b) Security	Class B common shares, par value $0.01 per share
Trading Symbol	HG
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		64,196,974
Entity Central Index Key	0001593275
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets
Investments, at fair value	$ 2,828,131	$ 2,260,146
Investments in Two Sigma Funds, at fair value (cost 2024: $829,606; 2023: $770,191)	932,787	851,470
Total investments	3,760,918	3,111,616
Cash and cash equivalents	957,372	794,509
Restricted cash and cash equivalents	93,883	106,351
Premiums receivable	885,744	658,363
Paid losses recoverable	146,008	145,202
Deferred acquisition costs	205,953	156,895
Unpaid losses and loss adjustment expenses recoverable	1,190,465	1,161,077
Receivables for investments sold	39,079	42,419
Prepaid reinsurance	260,174	194,306
Intangible assets	94,441	90,996
Other assets	192,510	209,621
Total assets	7,826,547	6,671,355
Liabilities
Reserve for losses and loss adjustment expenses	3,434,800	3,030,037
Unearned premiums	1,192,071	911,222
Reinsurance balances payable	334,511	272,310
Payables for investments purchased	172,905	66,606
Term loan, net of issuance costs	149,916	149,830
Accounts payable and accrued expenses	168,658	186,887
Payables to related parties	0	6,480
Total liabilities	5,452,861	4,623,372
Non-controlling interest – TS Hamilton Fund	60,060	133
Shareholders’ equity
Common shares:	1,014	1,101
Additional paid-in capital	1,172,331	1,249,817
Accumulated other comprehensive loss	(4,441)	(4,441)
Retained earnings	1,144,722	801,373
Total shareholders’ equity	2,313,626	2,047,850
Total liabilities, non-controlling interest, and shareholders’ equity	7,826,547	6,671,355
Total fixed maturities
Assets
Investments, at fair value	2,320,184	1,831,268
Short-term investments
Assets
Investments, at fair value	507,947	428,878
Common Class A
Shareholders’ equity
Common shares:	178	286
Common Class B
Shareholders’ equity
Common shares:	637	560
Common Class C
Shareholders’ equity
Common shares:	$ 199	$ 255

Unaudited Condensed Consolida_2

Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Investments, amortized cost	$ 2,812,412		$ 2,294,936
Investments in two sigma funds, cost	$ 829,606		$ 770,191
Common stock authorized (in shares)	150,000,000	150,000,000	150,000,000	150,000,000	135,000,000	135,000,000
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock issued (in shares)	101,392,722	101,922,771	110,225,103	103,704,006	103,683,894	103,087,859
Common stock outstanding (in shares)	101,392,722	101,922,771	110,225,103	103,704,006	103,683,894	103,087,859
Total fixed maturities
Investments, amortized cost	$ 2,306,168		$ 1,867,499
Short-term investments
Investments, amortized cost	$ 506,244		$ 427,437
Common Class A
Common stock authorized (in shares)	26,944,807	28,644,807	28,644,807	53,993,690	53,993,690	53,993,690
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock issued (in shares)	17,820,078	19,520,078	28,644,807	30,520,078	30,520,078	30,520,078
Common stock outstanding (in shares)	17,820,078	19,520,078	28,644,807	30,520,078	30,520,078	30,520,078
Common Class B
Common stock authorized (in shares)	79,677,932	72,837,352	72,337,352	65,480,684	50,480,684	50,480,684
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock issued (in shares)	63,668,995	57,358,464	56,036,067	42,658,302	42,638,190	42,042,155
Common stock outstanding (in shares)	63,668,995	57,358,464	56,036,067	42,658,302	42,638,190	42,042,155
Common Class C
Common stock authorized (in shares)	19,903,649	25,044,229	25,544,229	30,525,626	30,525,626	30,525,626
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock issued (in shares)	19,903,649	25,044,229	25,544,229	30,525,626	30,525,626	30,525,626
Common stock outstanding (in shares)	19,903,649	25,044,229	25,544,229	30,525,626	30,525,626	30,525,626

Unaudited Condensed Consolida_3

Unaudited Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues
Gross premiums written	$ 553,401	$ 474,123	$ 1,878,645	$ 1,517,247
Reinsurance premiums ceded	(75,505)	(90,557)	(410,802)	(400,475)
Net premiums written	477,896	383,566	1,467,843	1,116,772
Net change in unearned premiums	(29,101)	(46,530)	(214,981)	(164,374)
Net premiums earned	448,795	337,036	1,252,862	952,398
Net realized and unrealized gains (losses) on investments	48,228	47,343	454,851	101,881
Net investment income (loss)	17,330	8,069	43,667	17,719
Total net realized and unrealized gains (losses) on investments and net investment income (loss)	65,558	55,412	498,518	119,600
Other income (loss)	4,464	2,386	17,934	7,838
Net foreign exchange gains (losses)	(5,973)	1,432	(9,883)	(3,953)
Total revenues	512,844	396,266	1,759,431	1,075,883
Expenses
Losses and loss adjustment expenses	273,632	191,577	720,478	519,554
Acquisition costs	102,201	78,537	283,059	220,532
General and administrative expenses	62,392	63,035	182,164	158,075
Amortization of intangible assets	5,204	2,794	11,773	7,869
Interest expense	5,351	5,288	17,090	16,007
Total expenses	448,780	341,231	1,214,564	922,037
Income (loss) before income tax	64,064	55,035	544,867	153,846
Income tax expense (benefit)	3,029	2,387	6,118	6,908
Net income (loss)	61,035	52,648	538,749	146,938
Net income (loss) attributable to non-controlling interest	(17,215)	9,065	172,240	15,076
Net income (loss) and other comprehensive income (loss) attributable to common shareholders	$ 78,250	$ 43,583	$ 366,509	$ 131,862
Per share data
Basic income (loss) per share attributable to common shareholders (in dollars per share)	$ 0.77	$ 0.42	$ 3.45	$ 1.27
Diluted income (loss) per share attributable to common shareholders (in dollars per share)	$ 0.74	$ 0.41	$ 3.33	$ 1.26

Unaudited Condensed Consolida_4

Unaudited Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common shares	Additional paid-in capital	Accumulated other comprehensive income (loss)	Retained earnings
Balance, beginning of period at Dec. 31, 2022		$ 1,031	$ 1,120,242	$ (4,441)	$ 547,352
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares		8	(8)
Repurchases of common shares		(2)	(1,776)		(469)
Share compensation expense			10,095		(4,169)
Net income (loss)	$ 146,938				146,938
Net income (loss) attributable to non-controlling interest	(15,076)				(15,076)
Balance, end of period at Sep. 30, 2023	1,799,725	1,037	1,128,553	(4,441)	674,576
Balance, beginning of period at Jun. 30, 2023		1,036	1,124,566	(4,441)	630,993
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares		1	(1)
Repurchases of common shares		0	0		0
Share compensation expense			3,988		0
Net income (loss)	52,648				52,648
Net income (loss) attributable to non-controlling interest	(9,065)				(9,065)
Balance, end of period at Sep. 30, 2023	1,799,725	1,037	1,128,553	(4,441)	674,576
Balance, beginning of period at Dec. 31, 2023	2,047,850	1,101	1,249,817	(4,441)	801,373
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares		11	386
Repurchases of common shares		(98)	(100,136)		(23,160)
Share compensation expense			22,264		0
Net income (loss)	538,749				538,749
Net income (loss) attributable to non-controlling interest	(172,240)				(172,240)
Balance, end of period at Sep. 30, 2024	2,313,626	1,014	1,172,331	(4,441)	1,144,722
Balance, beginning of period at Jun. 30, 2024		1,019	1,171,585	(4,441)	1,070,384
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares		0	0
Repurchases of common shares		(5)	(6,092)		(3,912)
Share compensation expense			6,838		0
Net income (loss)	61,035				61,035
Net income (loss) attributable to non-controlling interest	17,215				17,215
Balance, end of period at Sep. 30, 2024	$ 2,313,626	$ 1,014	$ 1,172,331	$ (4,441)	$ 1,144,722

Unaudited Condensed Consolida_5

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Operating activities
Net income (loss)	$ 538,749	$ 146,938
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	13,081	8,990
Share compensation expense	22,264	10,095
Net realized (gains) losses on investments	(382,646)	(32,363)
Change in net unrealized (gains) losses on investments	(72,205)	(69,518)
Other items	(11,786)	1,330
Change in:
Premiums receivable	(227,381)	(166,372)
Paid losses recoverable	(806)	(47,659)
Deferred acquisition costs	(49,058)	(36,167)
Prepaid reinsurance	(65,868)	(67,898)
Unpaid losses and loss adjustment expenses recoverable	(29,388)	20,740
Other assets	17,111	3,253
Reserve for losses and loss adjustment expenses	404,763	92,547
Unearned premiums	280,849	233,408
Reinsurance balances payable	62,201	123,634
Accounts payable and accrued expenses and other	(24,667)	26,711
Net cash provided by (used in) operating activities	475,213	247,669
Investing activities
Proceeds from redemptions from Two Sigma Funds	2,129,185	1,821,046
Contributions to Two Sigma Funds	(1,836,664)	(1,954,119)
Purchases of fixed maturity investments	(1,466,805)	(809,646)
Proceeds from sales, redemptions and maturity of fixed maturity investments	1,032,664	418,677
Purchases of short-term investments	(1,335,003)	(1,078,631)
Proceeds from sales of short-term investments	1,288,278	1,032,091
Change in receivables for investments sold	3,340	(18,673)
Change in payables for investments purchased	106,299	69,741
Other	(16,570)	(11,425)
Net cash provided by (used in) investing activities	(95,276)	(530,939)
Financing activities
Issuance of common shares	11	8
Repurchases of common shares	(123,394)	(2,247)
Contribution of additional paid-in capital	386	(8)
Withdrawal of non-controlling interest	(112,313)	(15,066)
Net cash provided by (used in) financing activities	(235,310)	(17,313)
Effect of exchange rate changes on cash and cash equivalents and restricted cash and cash equivalents	5,768	(3,093)
Net increase (decrease) in cash and cash equivalents and restricted cash and cash equivalents	150,395	(303,676)
Cash and cash equivalents and restricted cash and cash equivalents, beginning of period	900,860	1,207,203
Cash and cash equivalents and restricted cash and cash equivalents, end of period	$ 1,051,255	$ 903,527

Organization

Organization	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Hamilton Insurance Group, Ltd. ("Hamilton Group", the "Group" or the "Company"), the ultimate group holding company, was incorporated on September 4, 2013, under the laws of Bermuda. On November 14, 2023, the Company consummated an initial public offering ("IPO") of its Class B common shares, which are listed on the NYSE. Our Bermuda operations are led by Hamilton Re, Ltd. ("Hamilton Re"), a registered Class 4 insurer incorporated in Bermuda. Hamilton Re writes property, casualty, and specialty insurance and reinsurance on a global basis. Hamilton Re US is a tax partnership that was formed pursuant to an arrangement between Hamilton Re and its Bermuda-incorporated affiliate, Hamilton ILS Holdings Limited. The tax partnership is treated as a U.S. corporation for U.S. tax purposes and is registered with the U.S. Internal Revenue Service, such that underwriting and investment income derived from capital allocated to Hamilton Re US are subject to U.S. taxation. Ada Capital Management Limited ("ACML"), a wholly owned insurance agent incorporated and regulated in Bermuda, is authorized to underwrite on behalf of Ada Re, Ltd. ("Ada Re"). Our London operations are comprised of Hamilton Managing Agency Limited ("HMA"), a Lloyd’s managing agency, which manages our wholly aligned Syndicate 4000 and a third-party funded Lloyd’s Syndicate. Syndicate 4000 operates in the Lloyd’s market and underwrites property, casualty, and specialty insurance and reinsurance business on a subscription basis. Our Dublin operations are comprised of Hamilton Insurance Designated Activity Company ("HIDAC"), a Dublin-based insurer with a U.K. branch and extensive licensing in the United States, including excess and surplus lines and reinsurance in all 50 states. Hamilton Managing General Agency Americas LLC ("HMGA Americas") is licensed throughout the United States and underwrites on behalf of the Group's London, Dublin and Bermuda operations solely in respect of Hamilton Re US, providing access from the U.S. to the Lloyd's market, the Group's rated Irish carrier and the Group's Bermuda balance sheet, respectively. Hamilton Select Insurance Inc. ("Hamilton Select") is a U.S. domestic excess and surplus lines carrier incorporated in Delaware and authorized to write excess and surplus business in all 50 states. Two Sigma Hamilton Fund, LLC ("TS Hamilton Fund"), is a Delaware limited liability company. In 2013, Hamilton Re entered into a limited liability company agreement with TS Hamilton Fund and Two Sigma Principals, LLC (the "Managing Member") as the managing member of TS Hamilton Fund. Effective July 1, 2023, Hamilton Re has committed to an investment in TS Hamilton Fund in an amount up to the lesser of (i) $1.8 billion or (ii) 60% of Hamilton Group’s net tangible assets (previously equal to a minimum of 95% of the consolidated net tangible assets of Hamilton Group). TS Hamilton Fund has engaged Two Sigma Investments, LP ("Two Sigma"), a related party Delaware limited partnership, to serve as its investment manager. Two Sigma is a United States Securities and Exchange Commission registered investment adviser specializing in quantitative analysis (see Note 3, Investments for further details). Unconsolidated Related Parties Ada Re is a special purpose insurer funded by third party investors and formed to provide fully collateralized reinsurance and retrocession to both Hamilton Group and third-party cedants. Easton Re has issued an industry loss index-triggered catastrophe bond that provides the Company's operating platforms with multi-year risk transfer capacity to protect against named storm risk in the United States and earthquake risk in the United States and Canada. See Note 7, Reinsurance , for further details.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies There have been no material changes to the Company's significant accounting policies as described in its Annual Report on Form 10-K for the year ended December 31, 2023, (the "Form 10-K"), except as described below. a. Basis of Presentation These unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP") and Article 10 of Regulation S-X, for interim financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In addition, the year-end balance sheet data was derived from audited financial statements but does not include all disclosures required by GAAP. In the opinion of management, these unaudited condensed consolidated financial statements reflect all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of the Company's financial position and results of operations as at the end of, and for, the periods presented. These financial statements include the accounts of Hamilton Group, Hamilton Re, Hamilton U.K. Holdings Limited, Hamilton Select, HMGA Americas, ACML, and TS Hamilton Fund (collectively the "Company"). All significant intercompany transactions and balances have been eliminated on consolidation . Certain comparative information has been reclassified to conform to the current year presentation. b. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The major estimates recorded in the Company’s financial statements include, but are not limited to, premiums written, provisions for estimated future credit losses, the reserve for losses and loss adjustment expenses and the fair value of investments. c. Recent Accounting Pronouncements Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07 Segment Reporting , which enhances the qualitative and quantitative disclosures related to reportable segments. The guidance is effective for annual periods beginning after December 15, 2023 and interim periods beginning after December 15, 2024. Early adoption is permitted. This guidance will not have a material impact on the Company's results of operations, financial position, or cash flows. In December 2023, the FASB issued ASU 2023-09 Income Taxes , which enhances the quantitative annual disclosures related to tax rate reconciliations and income taxes paid and requires additional qualitative discussion of applicable tax jurisdictions and the nature of certain reconciling items. The guidance is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. This guidance will not have a material impact on the Company's results of operations, financial position, or cash flows.

Investments

Investments	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Investments	Investments Fixed Maturity and Short-Term Investments - Trading The Company’s fixed maturity and short-term investments are as follows: September 30, 2024 ($ in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturities: U.S. government treasuries $ 761,334 $ 9,273 $ (5,679) $ 764,928 U.S. states, territories and municipalities 13,528 114 (175) 13,467 Non-U.S. sovereign governments and supranationals 74,679 3,029 (532) 77,176 Corporate 1,118,605 24,677 (9,485) 1,133,797 Residential mortgage-backed securities - Agency 258,788 3,069 (10,343) 251,514 Residential mortgage-backed securities - Non-agency 5,790 109 (540) 5,359 Commercial mortgage-backed securities - Non-agency 33,189 535 (615) 33,109 Other asset-backed securities 40,255 660 (81) 40,834 Total fixed maturities 2,306,168 41,466 (27,450) 2,320,184 Short-term investments 506,244 1,709 (6) 507,947 Total $ 2,812,412 $ 43,175 $ (27,456) $ 2,828,131 December 31, 2023 ($ in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturities: U.S. government treasuries $ 717,134 $ 5,137 $ (14,021) $ 708,250 U.S. states, territories and municipalities 4,656 — (286) 4,370 Non-U.S. sovereign governments and supranationals 55,662 2,175 (1,591) 56,246 Corporate 877,493 8,443 (22,060) 863,876 Residential mortgage-backed securities - Agency 180,661 435 (12,583) 168,513 Residential mortgage-backed securities - Non-agency 5,639 16 (671) 4,984 Commercial mortgage-backed securities - Non-agency 11,473 — (1,050) 10,423 Other asset-backed securities 14,781 20 (195) 14,606 Total fixed maturities 1,867,499 16,226 (52,457) 1,831,268 Short-term investments 427,437 1,441 — 428,878 Total $ 2,294,936 $ 17,667 $ (52,457) $ 2,260,146 Contractual Maturities Summary The following table presents contractual maturities of fixed maturity securities. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2024 ($ in thousands) Amortized Cost Fair Value Due less than one year $ 149,305 $ 148,136 Due after one through five years 1,590,516 1,607,936 Due after five through ten years 224,518 229,859 Due after ten years 3,807 3,437 Mortgage-backed securities 297,767 289,982 Asset-backed securities 40,255 40,834 Total $ 2,306,168 $ 2,320,184 Investments in Two Sigma Funds The Company’s investments in Two Sigma Funds are as follows: September 30, 2024 December 31, 2023 ($ in thousands) Cost Net Unrealized Gains (Losses) Fair Value Cost Net Unrealized Gains (Losses) Fair Value Two Sigma Futures Portfolio, LLC (FTV) $ 352,138 $ 7,017 $ 359,155 $ 433,911 $ (38,105) $ 395,806 Two Sigma Spectrum Portfolio, LLC (STV) 337,247 55,581 392,828 193,299 88,228 281,527 Two Sigma Equity Spectrum Portfolio, LLC (ESTV) 140,221 40,583 180,804 142,981 31,156 174,137 Total $ 829,606 $ 103,181 $ 932,787 $ 770,191 $ 81,279 $ 851,470 The Company, through its investments in FTV, STV and ESTV, seeks to achieve absolute dollar-denominated returns on a substantial capital base, primarily by combining multiple hedged and leveraged systematic investment strategies with proprietary risk management and execution techniques. These systematic strategies include, but are not limited to, technical and statistically-based, fundamental-based, event-based, market condition-based and spread-based strategies as well as contributor-based and/or sentiment-based strategies and blended strategies. FTV primarily utilizes systematic strategies to gain broad macro exposure to FX, fixed income, equity and credit indices, and commodities, predominantly by trading futures, spots, forwards, options, swaps, cash bonds and exchange traded products. STV primarily utilizes systematic strategies to trade U.S.-listed equity securities and related instruments and derivatives. ESTV primarily utilizes systematic strategies to trade non-U.S.-listed equity securities and related instruments and derivatives. At September 30, 2024, the Company owns an 18.5%, 17.9% and 9.8% interest in each of the FTV, STV and ESTV funds, respectively. The following table summarizes certain investments of FTV, STV and ESTV where TS Hamilton Fund’s proportionate share of the fair value of the investment represents more than 5% of TS Hamilton Fund’s members’ equity: September 30, 2024 ($ in thousands) Principal / Shares (1) Fair Value (1) % of Members' Equity State Street Treasury Obligations Money Market Fund 185,175 $ 185,175 9.9 % U.S. Treasury Securities, 0.0000% - 4.2500%, due 10/29/2024 - 8/15/2044 2,049,275 $ 2,073,372 110.3 % State Street Institutional Treasury Plus Money Market Fund 98,599 $ 98,599 5.3 % U.S. Treasury Securities, 3.5000% - 4.2500%, due 9/30/2026 - 8/15/2054 (852,058) $ (850,202) (45.2) % (1) Values represent TS Hamilton Fund’s proportionate share of the aggregate of FTV, STV and ESTV total holdings. Two Sigma and the Managing Member are related parties to the Company as described further in Note 1, Organization . Effective July 1, 2023, a revised investment management agreement with Two Sigma requires TS Hamilton Fund to incur a management fee of 2.5% of the non-managing members' equity in the net asset value of the TS Hamilton Fund per annum (previously 3%). The management fee for the three months ended September 30, 2024 and 2023 was $11.8 million and $10.4 million, respectively, and the management fee for the nine months ended September 30, 2024 and 2023 was $35.0 million and $34.4 million, respectively. Under the terms of the revised limited liability company agreement between Hamilton Re and the Managing Member, the Managing Member remains entitled to an incentive allocation equal to 30% of TS Hamilton Fund’s net profits, subject to high watermark provisions, and adjusted for withdrawals and any incentive allocation to the Managing Member. In the event there is a net loss during a quarter and a net profit during any subsequent quarter, the Managing Member is entitled to a modified incentive allocation whereby the regular incentive allocation will be reduced by 50% until subsequent cumulative net profits are credited in an amount equal to 200% of the previously allocated net losses. The Managing Member is also entitled to receive a revised additional incentive allocation as of the end of each fiscal year (or on any date Hamilton Re withdraws all or a portion of its capital), in an amount equal to 25% of the Excess Profits (previously 20%). "Excess Profits" for any given fiscal year (or other such accounting period) means the net profits over 10% for such fiscal year (previously 15%), net of management fees and expenses and gross of incentive allocations, but only after recouping previously unrecouped net losses. To the extent Hamilton Re contributes capital other than at the beginning of a fiscal year or withdraws capital other than at the end of a fiscal year, the additional incentive allocation hurdle with respect to such capital is prorated. The aggregate incentive allocation (inclusive of the additional incentive allocation) for the three months ended September 30, 2024 and 2023 was $(17.2) million and $9.1 million, respectively, and the aggregate incentive allocation (inclusive of the additional incentive allocation) for the nine months ended September 30, 2024 and 2023 was $172.2 million and $15.1 million, respectively. Hamilton Re has a commitment with TS Hamilton Fund to maintain an amount up to the lesser of (i) $1.8 billion or (ii) 60% of Hamilton Insurance Group’s net tangible assets in TS Hamilton Fund, such lesser amount, the "Minimum Commitment Amount", for a three-year period (the "Initial Term") and for rolling three-year periods thereafter (each such three-year period the "Commitment Period"), subject to certain circumstances and the liquidity options described below, with the Commitment Period ending on June 30, 2027. The Commitment Period consists of a 3-year rolling term that automatically renews on an annual basis unless Hamilton Re or the Managing Member provide advance notice of non-renewal. The TS Hamilton Fund generally has two liquidity options, subject to Hamilton Re’s minimum investment commitment, which are as follows: • Monthly liquidity - Subject to certain conditions, Hamilton Re may request a whole or partial withdrawal of its capital account, no later than fifteen days prior to the end of a calendar month, effective as of the last day of such calendar month. • Daily liquidity - Subject to certain limited circumstances, including the need to meet obligations pursuant to Hamilton Re’s underwriting operations, Hamilton Re may request a withdrawal of all or a portion of its capital account upon at least one At its discretion, the Managing Member may permit or require Hamilton Re to withdraw all or any portion of its respective capital account at other times, or waive or reduce certain notice periods, or allow a notice to be revoked. The Managing Member may withdraw all or any portion of its capital account at any time. Total Net Realized and Unrealized Gains (Losses) on Investments and Net Investment Income (Loss) The components of total net realized and unrealized gains (losses) on investments and net investment income (loss) are as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Net realized and unrealized gains (losses) on investments: Net realized gains (losses) on investments $ 93,711 $ 42,403 $ 382,646 $ 32,363 Change in net unrealized gains (losses) on investments (45,483) 4,940 72,205 69,518 Net realized and unrealized gains (losses) on investments 48,228 47,343 454,851 101,881 Net investment income (loss): Fixed maturities 22,067 12,208 58,025 31,178 Short-term investments 10 38 50 287 TS Hamilton Fund 3,108 3,121 9,040 13,033 Cash and cash equivalents 4,384 4,029 12,594 8,752 Other 306 (104) 1,473 1,015 Interest and other 29,875 19,292 81,182 54,265 Management fees (12,207) (10,958) (36,640) (35,806) Other expenses (338) (265) (875) (740) Net investment income (loss) 17,330 8,069 43,667 17,719 Total net realized and unrealized gains (losses) on investments and net investment income (loss) $ 65,558 $ 55,412 $ 498,518 $ 119,600 Net Realized Gains (Losses) on Investments The components of net realized gains (losses) on investments are as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Fixed maturities and short-term investments $ 2,769 $ (7,688) $ (1,866) $ (10,796) TS Hamilton Fund 90,942 50,091 384,228 42,948 Other — — 284 211 Net realized gains (losses) on investments $ 93,711 $ 42,403 $ 382,646 $ 32,363 Net Unrealized Gains (Losses) on Investments The components of net unrealized gains (losses) on investments are as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Fixed maturities and short-term investments $ 64,903 $ (12,818) $ 50,304 $ (9,800) TS Hamilton Fund (110,386) 17,758 21,901 79,318 Net unrealized gains (losses) on investments $ (45,483) $ 4,940 $ 72,205 $ 69,518 Pledged Assets At September 30, 2024 and December 31, 2023, pledged investments at fair value were comprised of $250.3 million and $232.2 million, respectively, securing a portion of the capital requirements for business written at Lloyd's, $89.1 million and $54.1 million, respectively, held in trust accounts for the benefit of U.S. state regulatory authorities and $32.5 million and $37.2 million respectively, securing other underwriting obligations. In addition, certain investments were pledged as security for letter of credit facilities as described further in Note 10, Debt and Credit Facilities . At September 30, 2024 and December 31, 2023, restricted cash and cash equivalents balances were comprised of $89.6 million and $97.4 million, respectively, securing other underwriting obligations, $2.7 million and $7.2 million, respectively, securing a portion of the capital requirements for business written at Lloyd's, $1.6 million and $1.5 million, respectively, in trust accounts for the benefit of regulatory authorities, and $Nil and $0.3 million, respectively, of escrow funds. Total cash and cash equivalents and restricted cash and cash equivalents of $1.1 billion presented in the statement of cash flows was comprised of cash and cash equivalents of $1.0 billion and restricted cash and cash equivalents of $93.9 million on the balance sheet at September 30, 2024. Total cash and cash equivalents and restricted cash and cash equivalents of $900.9 million presented in the statement of cash flows at December 31, 2023 was comprised of cash and cash equivalents of $794.5 million and restricted cash and cash equivalents of $106.4 million on the balance sheet.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value	Fair Value Financial Instruments Subject to Fair Value Measurements Accounting guidance over fair value measurements requires that a fair value measurement reflect the assumptions market participants would use in pricing an asset or liability based on the best information available. Assumptions include the risks inherent in a particular valuation technique (such as a pricing model) and/or the risks inherent in the inputs to the model. The fair value of a financial instrument is the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (the "exit price"). Instruments that the Company owns are marked to bid prices. Basis of Fair Value Measurements Fair value measurement accounting guidance also establishes a fair value hierarchy that prioritizes the inputs to the respective valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). An asset or liability’s classification within the fair value hierarchy is based on the lowest level of significant input to its valuation. The three levels of the fair value hierarchy are: • Level 1 - Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date; • Level 2 - Inputs other than quoted prices included within Level 1 that are observable for the asset or liability either directly or indirectly, including inputs in markets that are not considered to be active; and • Level 3 - Inputs that are both significant to the fair value measurement and unobservable. Assets Recorded at Fair Value - Fixed Maturity and Short-term Investments The following section describes the valuation methodologies used to determine the fair value of the Company’s fixed maturity and short-term investments by asset class: • U.S. government treasuries: fair value based on observable market inputs such as quoted prices, reported trades, quoted prices for similar issuances and benchmark yields; • U.S. states, territories and municipalities: fair value based on observable market inputs such as quoted market prices, quoted prices for similar securities, benchmark yields and credit spreads; • Non-U.S. sovereign governments and supranationals: fair value based on observable market inputs such as quoted market prices, quoted prices for similar securities and models with observable inputs such as benchmark yields and credit spreads, and then, where applicable, converted to U.S. dollars using an exchange rate from a nationally recognized source; • Corporate: fair value based on observable market inputs such as quoted market prices, quoted prices for similar securities, benchmark yields and credit spreads; • Asset-backed and mortgage-backed securities: fair value based on observable inputs such as quoted prices, reported trades, quoted prices for similar issuances or benchmark yields and cash flow models using observable inputs such as prepayment speeds, collateral performance and default spreads; and • Short-term investments: fair value based on observable market inputs such as quoted prices, reported trades, quoted prices for similar issuances and benchmark yields. The following table presents the financial instruments measured at fair value on a recurring basis: September 30, 2024 ($ in thousands) Level 1 Level 2 Level 3 Total Fixed maturities: U.S. government treasuries $ — $ 764,928 $ — $ 764,928 U.S. states, territories and municipalities — 13,467 — 13,467 Non-U.S. sovereign governments and supranationals — 77,176 — 77,176 Corporate — 1,133,797 — 1,133,797 Residential mortgage-backed securities - Agency — 251,514 — 251,514 Residential mortgage-backed securities - Non-agency — 5,359 — 5,359 Commercial mortgage-backed securities - Non-agency — 33,109 — 33,109 Other asset-backed securities — 40,834 — 40,834 Total fixed maturities — 2,320,184 — 2,320,184 Short-term investments — 507,947 — 507,947 Total $ — $ 2,828,131 $ — $ 2,828,131 December 31, 2023 ($ in thousands) Level 1 Level 2 Level 3 Total Fixed maturities: U.S. government treasuries $ — $ 708,250 $ — $ 708,250 U.S. states, territories and municipalities — 4,370 — 4,370 Non-U.S. sovereign governments and supranationals — 56,246 — 56,246 Corporate — 863,876 — 863,876 Residential mortgage-backed securities - Agency — 168,513 — 168,513 Residential mortgage-backed securities - Non-agency — 4,984 — 4,984 Commercial mortgage-backed securities - Non-agency — 10,423 — 10,423 Other asset-backed securities — 14,606 — 14,606 Total fixed maturities — 1,831,268 — 1,831,268 Short-term investments — 428,878 — 428,878 Total $ — $ 2,260,146 $ — $ 2,260,146

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	Variable Interest Entities TS Hamilton Fund TS Hamilton Fund meets the definition of a variable interest entity ("VIE") principally because the Managing Member does not hold substantive equity at risk in the entity but controls all of the decision making authority over it. Therefore, the Company assessed its ownership in the VIE to determine if it is the primary beneficiary. The Managing Member is a related party to the Company and collectively they hold all of the variable interest. The Company performed an assessment of all relevant facts and circumstances and determined that it is the entity within the related party group for whom substantially all of the activities of the VIE are conducted. As a result, the Company concluded that it is the primary beneficiary of TS Hamilton Fund. Activity in the non-controlling interest of TS Hamilton Fund was as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Balance - beginning of period $ 77,275 $ 124 $ 133 $ 119 Withdrawals — (9,060) (112,313) (15,066) Equity in earnings (1) 5 33 10 Incentive allocation (17,214) 9,060 172,207 15,066 Balance - end of period $ 60,060 $ 129 $ 60,060 $ 129 The following table presents the total assets and total liabilities of TS Hamilton Fund. Creditors or beneficial interest holders of TS Hamilton Fund have no recourse to the general credit of the Company as the Company’s obligation is limited to the amount of its committed investment. ($ in thousands) September 30, December 31, Assets Cash and cash equivalents $ 560,757 $ 479,255 Short-term investments 507,947 428,878 Investments in Two Sigma Funds, at fair value 932,787 851,470 Receivables for investments sold 28,977 41,087 Interest and dividends receivable 1,184 966 Total assets 2,031,652 1,801,656 Liabilities Accounts payable and accrued expenses 190 191 Withdrawal payable — 6,480 Payable for investments purchased 151,754 62,440 Total liabilities 151,944 69,111 Total net assets managed by TS Hamilton Fund $ 1,879,708 $ 1,732,545

Value Appreciation Pool

Value Appreciation Pool	9 Months Ended
	Sep. 30, 2024
Share-Based Payment Arrangement [Abstract]
Value Appreciation Pool	Value Appreciation Pool The Value Appreciation Pool ("VAP") is a long-term incentive compensation plan that rewarded employees with 10% of the increase in the multiple of the Company's estimated fair market value to GAAP shareholders' equity between the December 1, 2020 VAP inception date and the Company's Initial Public Offering on November 10, 2023. As a then nonpublic company, the VAP was initially measured at intrinsic value and no compensation cost was recorded over the period December 1, 2020 to March 31, 2023. On May 15, 2023, the Company became a public business entity and the VAP was remeasured at fair value. The fair value of the compensation cost was estimated at each reporting date and expensed over the period for which the employee is required to provide services in exchange for the award, with any changes recorded in compensation expense by a cumulative catch-up adjustment. In the fourth quarter of 2023, the Company consummated an IPO of its Class B common shares and, on November 10, 2023, closed its first day of trading. In accordance with the Compensation Committee's decision that the VAP award would be settled in shares if triggered by an IPO, the VAP became subject to equity award accounting. The VAP RSUs vest in two tranches, subject to continued service: 50% on each of the first and second anniversaries of the November 10, 2023 trigger event. Participants who leave prior to vesting forfeit any previously unsettled portion of their awards. The Company recorded a compensation expense of $1.9 million and $11.2 million for the three months ended September 30, 2024 and 2023, respectively. The Company recorded a compensation expense of $7.5 million and $15.6 million for the nine months ended September 30, 2024 and 2023, respectively. Of the total expense recognized for the nine months ended September 30, 2023, $4.2 million was recorded as an adjustment to retained earnings in "Share compensation expense" in the second quarter of 2023. See Note 13. Stock Incentive Plans in the audited consolidated financial statements included in our Form 10-K for the year ended December 31, 2023 for further details.

Reinsurance

Reinsurance	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Reinsurance	Reinsurance The Company purchases reinsurance and other protection to manage its risk portfolio and to reduce its exposure to large losses. The Company currently has in place contracts that provide for recovery of a portion of certain loss and loss adjustment expenses, generally in excess of various retentions or on a proportional basis. Amounts recoverable under reinsurance contracts are recorded as assets. The Company remains liable to the extent that any reinsurance company fails to meet its obligations. Allowance for Expected Credit Losses Premiums receivable, paid losses recoverable, and unpaid losses and loss adjustment expenses recoverable comprise the Company's most significant credit exposures not carried at fair value. The Company has not historically experienced significant credit losses. In determining an allowance for these assets, the Company considers historical information in combination with counterparty financial strength ratings and the extent to which balances are collateralized. The Company assesses the risk of future default by evaluating current market conditions for the likelihood of default and calculates its provision for current expected credit losses under the probability of default and loss given default methodology. Premiums Receivable Premiums receivable are estimated based on policy terms and reports received from the underlying counterparties, supplemented by management's judgment. Due to the nature of the (re)insurance business, the Company routinely receives reports and premiums subsequent to the inception of the coverage period. At September 30, 2024, the Company’s premiums receivable balance, net of credit provisions of $2.0 million, was $885.7 million. At December 31, 2023, the Company’s premiums receivable balance, net of credit provisions of $3.0 million, was $658.4 million. The following table provides a roll forward of the provision for current expected credit losses of the Company's premiums receivable: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Beginning balance $ 1,962 $ 3,098 $ 3,000 $ 2,856 Increase (decrease) in allowance 46 (356) (992) (114) Ending balance $ 2,008 $ 2,742 $ 2,008 $ 2,742 Reinsurance Balances Recoverable Reinsurance balances recoverable is comprised of amounts due from reinsurers based on the claim liabilities associated with the reinsured policy. The Company accrues amounts due from reinsurers based on estimated ultimate contract losses. At September 30, 2024, the Company’s paid and unpaid reinsurance recoverable balances net of credit provisions were $146.0 million and $1.2 billion, respectively, with a total corresponding provision for current expected credit losses of $0.8 million. At December 31, 2023, the Company’s paid and unpaid reinsurance recoverable balances net of credit provisions were $145.2 million and $1.2 billion, respectively, with a total corresponding provision for current expected credit losses of $0.7 million. The following table provides a roll forward of the provision for current expected credit losses of the Company's reinsurance recoverable: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Beginning balance $ 755 $ 820 $ 687 $ 777 Increase (decrease) in allowance 78 (129) 146 (86) Ending balance $ 833 $ 691 $ 833 $ 691 The distribution of the Company’s paid losses recoverable and unpaid losses and loss adjustment expenses recoverable as categorized by major rating agencies were as follows: Classification September 30, December 31, Collateralized 24.9 % 28.5 % A- or better 74.9 % 71.0 % Below A- 0.2 % 0.5 % Total 100.0 % 100.0 % At September 30, 2024 and December 31, 2023, the three largest balances by reinsurer accounted for 24%, 21% and 13%, and 27%, 20% and 12%, respectively, of paid losses recoverable and unpaid losses and loss adjustment expenses recoverable. Loss Portfolio Transfer On February 6, 2020, the Company entered into a loss portfolio transfer agreement (the "LPT"), under which the insurance liabilities arising from certain casualty risks for the Lloyd's Years of Account ("YOA") 2016, 2017 and 2018 were retroceded to a third party in exchange for total premium of $72.1 million. This transaction was accounted for as retroactive reinsurance under which cumulative ceded losses exceeding the LPT premium are recognized as a deferred gain liability and amortized into income over the settlement period of the ceded reserves in proportion to cumulative losses collected over the estimated ultimate reinsurance recoverable. The amount of the deferral is recalculated each reporting period based on updated ultimate loss estimates. Consequently, cumulative adverse development subsequent to the signing of the LPT may result in significant losses from operations until periods when the deferred gain is recognized as a benefit to earnings. At September 30, 2024 and December 31, 2023, the balance of reinsurance recoverable on unpaid losses due under this LPT was $44.2 million and $49.8 million, respectively. Amortization of the deferred gain was an expense of $0.6 million and $0.9 million during the three months ended September 30, 2024 and 2023, respectively, and income of $1.3 million and $2.5 million during the nine months ended September 30, 2024 and 2023, respectively, which was recorded through losses and loss adjustment expenses in accordance with the actual loss payments and updated estimates of ultimate losses of the subject business. Catastrophe Bond Reinsurance In December 2023, Hamilton Group sponsored an industry loss index-triggered catastrophe bond through the issuance of Series 2024-1 Class A Principal-at-Risk Variable Rate Notes by Bermuda-domiciled Easton Re Ltd. ("Easton Re"), which provide the Company's operating platforms with multi-year risk transfer capacity of $200 million to protect against named storm risk in the United States and earthquake risk in the United States and Canada. The risk period for Easton Re is from January 1, 2024 to December 31, 2026. The Company recorded reinsurance premiums ceded of $Nil and $14.6 million during the three and nine months ended September 30, 2024, respectively.

Reserve for Losses and Loss Adj

Reserve for Losses and Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Reserve for Losses and Loss Adjustment Expenses	Reserve for Losses and Loss Adjustment Expenses The following table presents a reconciliation of unpaid losses and loss adjustment expenses ("LAE") for the nine months ended September 30, 2024 and 2023: Nine Months Ended September 30, ($ in thousands) 2024 2023 Gross unpaid losses and loss adjustment expenses, beginning of period $ 3,030,037 $ 2,856,275 Reinsurance recoverable on unpaid losses 1,161,077 1,177,863 Net unpaid losses and loss adjustment expenses, beginning of period 1,868,960 1,678,412 Net losses and loss adjustment expenses incurred in respect of losses occurring in: Current year 726,602 528,457 Prior years (6,124) (8,903) Total incurred 720,478 519,554 Net losses and loss adjustment expenses paid in respect of losses occurring in: Current year 24,850 28,521 Prior years 344,992 397,407 Total paid 369,842 425,928 Foreign currency revaluation and other 24,739 19,661 Net unpaid losses and loss adjustment expenses, end of period 2,244,335 1,791,699 Reinsurance recoverable on unpaid losses 1,190,465 1,157,123 Gross unpaid losses and loss adjustment expenses, end of period $ 3,434,800 $ 2,948,822 Net favorable prior year development of $6.1 million for the nine months ended September 30, 2024 was primarily driven by $13.2 million of favorable prior year development on catastrophe losses, partially offset by $7.1 million of unfavorable development on attritional losses. See below for further details: • Net favorable development of $26.1 million on property contracts, primarily driven by favorable prior year development on catastrophe losses and overall lower than expected claims development across various classes; partially offset by • Net unfavorable development of $13.2 million on casualty contracts, primarily driven by higher than expected claims development across certain classes and unfavorable development of one specific large loss; and • Net unfavorable development of $9.5 million on specialty contracts, primarily driven by two specific large losses; and • In addition, casualty business protected by the LPT discussed in Note 7, Reinsurance, benefited from favorable development in the underlying reserves of $1.4 million and $1.3 million in amortization of the associated deferred gain, for a total net positive earnings impact of $2.7 million. Net favorable prior year development of $8.9 million for the nine months ended September 30, 2023 was comprised of $4.9 million and $4.0 million of favorable prior year development on catastrophe and attritional losses, respectively. See below for further details: • Net favorable development of $20.3 million on specialty contracts, driven by lower than expected claims development across various classes; offset by • Net unfavorable development of $8.8 million on casualty contracts, primarily related to higher than expected claims development across various classes; and • Net unfavorable development of $6.6 million on property contracts, primarily driven by higher than expected claims related to Winterstorm Elliot and development on certain attritional claims, including claims arising from exited classes of business; and • In addition, casualty business protected by the LPT discussed in Note 7, Reinsurance , benefited from $2.5 million in amortization of the associated deferred gain, which, in addition to favorable development in the underlying reserves of $1.5 million, had a total net positive earnings impact of $4.0 million. Reinsurance recoverable on unpaid losses related to the LPT discussed in Note 7, Reinsurance , was recognized for each of the nine months ended September 30, 2024 and 2023 in the reconciliation of beginning and ending gross and net loss and LAE reserves presented above. Acquisition Costs The Company amortized acquisition costs of $102.2 million and $78.5 million for the three months ended September 30, 2024 and 2023, respectively, and $283.1 million and $220.5 million for the nine months ended September 30, 2024 and 2023, respectively. Hurricane Helene On September 26, 2024, Hurricane Helene made landfall near the Big Bend region of Florida before traveling inland across the southeastern U.S. and dissipating over Tennessee on September 29, 2024. The level of uncertainty within the Company’s loss estimates for Hurricane Helene is increased by the fact that this event occurred in the final days of the fiscal quarter. As at September 30, 2024 and December 31, 2023, our net recorded reserves relating to Hurricane Helene totaled $33.9 million and $Nil, respectively. Baltimore Bridge Our net reserves for losses and loss adjustment expenses related to the Francis Scott Key Baltimore Bridge collapse on March 26, 2024 are also subject to significant uncertainty. As at September 30, 2024 and December 31, 2023, our recorded reserves totaled $37.9 million and $Nil, respectively. Ukraine Conflict Our net reserves for losses and loss adjustment expenses related to the ongoing Ukraine conflict are also subject to significant uncertainty. As at September 30, 2024 and December 31, 2023, our recorded reserves totaled $63.7 million and $64.9 million, respectively. Covid-19 Our Covid-19 losses are also subject to significant uncertainty. As at September 30, 2024 and December 31, 2023, our net recorded reserves relating to Covid-19 totaled $15.6 million and $14.1 million, respectively. While the Company believes, based on current facts and circumstances, that its estimates of net reserves for losses and loss adjustment expenses are adequate for losses and loss adjustment expenses that have been incurred at September 30, 2024, the Company will continue to monitor its assumptions as new information becomes available and will adjust its estimate of net reserves for losses and loss adjustment expenses as appropriate. Actual ultimate losses for these events may differ materially from the Company's current estimates.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company has determined its reportable business segments based on the information used by management in assessing performance and allocating resources to underwriting operations and has identified two reportable business segments - International and Bermuda. Each of the Company's identified reportable segments has a Chief Executive Officer who is responsible for the overall profitability of their segment and who regularly reports and is directly accountable to the chief operating decision maker: the Chief Executive Officer of the consolidated group. The Company evaluates the performance of reportable segments based on their respective underwriting income or loss. Underwriting income or loss is calculated as net premiums earned less losses and loss adjustment expenses, acquisition costs, and other underwriting expenses, net of third party fee income. General and administrative expenses not incurred by the reportable segments are included in corporate and other expenses as part of the reconciliation of net underwriting income or loss to net income or loss attributable to common shareholders. As the Company does not manage its assets by reportable segment, investment income and assets are not allocated to reportable segments. The Company's core business is underwriting and its underwriting results are reflected in its reportable segments: (1) International, which is comprised of property, casualty and specialty insurance and reinsurance classes of business originating from the Company’s London, Dublin, and Hamilton Select operations; and (2) Bermuda, which is comprised of property, casualty and specialty insurance and reinsurance classes of business originating from Hamilton Re, Bermuda and Hamilton Re US and subsidiaries. The Company considers many factors, including the nature of each segment’s products, client types, production sources, distribution methods and the regulatory environment, in determining the aggregated operating segments. Corporate includes net realized and unrealized gains (losses) on investments, net investment income (loss), other income (loss) not incurred by the reportable segments, net foreign exchange gains (losses), general and administrative expenses not incurred by the reportable segments, amortization of intangible assets, interest expense, and income tax expense (benefit). ($ in thousands) Three Months Ended September 30, 2024 International Bermuda Corporate Total Gross premiums written $ 325,525 $ 227,876 $ — $ 553,401 Net premiums written $ 268,106 $ 209,790 $ — $ 477,896 Net premiums earned $ 225,244 $ 223,551 $ — $ 448,795 Third party fee income 4,170 294 — 4,464 Losses and loss adjustment expenses 130,135 143,497 — 273,632 Acquisition costs 59,713 42,488 — 102,201 Other underwriting expenses 34,143 14,189 — 48,332 Underwriting income (loss) $ 5,423 $ 23,671 $ — $ 29,094 Net realized and unrealized gains (losses) on investments 48,228 48,228 Net investment income (loss) 17,330 17,330 Net foreign exchange gains (losses) (5,973) (5,973) Corporate expenses (14,060) (14,060) Amortization of intangible assets (5,204) (5,204) Interest expense (5,351) (5,351) Income (loss) before income tax 64,064 Income tax (expense) benefit (3,029) (3,029) Net income (loss) 61,035 Net income (loss) attributable to non-controlling interest (17,215) (17,215) Net income (loss) attributable to common shareholders $ 78,250 Key Ratios Attritional loss ratio - current year 55.3 % 51.0 % 53.2 % Attritional loss ratio - prior year development (1.5) % 0.0 % (0.7) % Catastrophe loss ratio - current year 6.4 % 16.7 % 11.5 % Catastrophe loss ratio - prior year development (2.4) % (3.5) % (3.0) % Loss and loss adjustment expense ratio 57.8 % 64.2 % 61.0 % Acquisition cost ratio 26.5 % 19.0 % 22.8 % Other underwriting expense ratio 13.3 % 6.2 % 9.8 % Combined ratio 97.6 % 89.4 % 93.6 % ($ in thousands) Three Months Ended September 30, 2023 International Bermuda Corporate Total Gross premiums written $ 307,140 $ 166,983 $ — $ 474,123 Net premiums written $ 234,621 $ 148,945 $ — $ 383,566 Net premiums earned $ 178,632 $ 158,404 $ — $ 337,036 Third party fee income 2,115 186 — 2,301 Losses and loss adjustment expenses 97,820 93,757 — 191,577 Acquisition costs 47,236 31,301 — 78,537 Other underwriting expenses 31,634 12,723 — 44,357 Underwriting income (loss) $ 4,057 $ 20,809 $ — $ 24,866 Net realized and unrealized gains (losses) on investments 47,343 47,343 Net investment income (loss) 8,069 8,069 Other income (loss), excluding third party fee income 85 85 Net foreign exchange gains (losses) 1,432 1,432 Corporate expenses (18,678) (18,678) Amortization of intangible assets (2,794) (2,794) Interest expense (5,288) (5,288) Income (loss) before income tax 55,035 Income tax (expense) benefit (2,387) (2,387) Net income (loss) 52,648 Net income (loss) attributable to non-controlling interest 9,065 9,065 Net income (loss) attributable to common shareholders $ 43,583 Key Ratios Attritional loss ratio - current year 54.6 % 55.1 % 54.8 % Attritional loss ratio - prior year development (5.3) % 5.7 % (0.1) % Catastrophe loss ratio - current year 5.1 % 2.6 % 3.9 % Catastrophe loss ratio - prior year development 0.4 % (4.2) % (1.8) % Loss and loss adjustment expense ratio 54.8 % 59.2 % 56.8 % Acquisition cost ratio 26.4 % 19.8 % 23.3 % Other underwriting expense ratio 16.5 % 7.9 % 12.5 % Combined ratio 97.7 % 86.9 % 92.6 % ($ in thousands) Nine Months Ended September 30, 2024 International Bermuda Corporate Total Gross premiums written $ 957,981 $ 920,664 $ — $ 1,878,645 Net premiums written $ 687,444 $ 780,399 $ — $ 1,467,843 Net premiums earned $ 637,700 $ 615,162 $ — $ 1,252,862 Third party fee income 11,557 6,377 — 17,934 Losses and loss adjustment expenses 359,181 361,297 — 720,478 Acquisition costs 160,589 122,470 — 283,059 Other underwriting expenses 99,317 41,022 — 140,339 Underwriting income (loss) $ 30,170 $ 96,750 $ — $ 126,920 Net realized and unrealized gains (losses) on investments 454,851 454,851 Net investment income (loss) 43,667 43,667 Net foreign exchange gains (losses) (9,883) (9,883) Corporate expenses (41,825) (41,825) Amortization of intangible assets (11,773) (11,773) Interest expense (17,090) (17,090) Income (loss) before income tax 544,867 Income tax (expense) benefit (6,118) (6,118) Net income (loss) 538,749 Net income (loss) attributable to non-controlling interest 172,240 172,240 Net income (loss) attributable to common shareholders $ 366,509 Key Ratios Attritional loss ratio - current year 54.6 % 53.1 % 53.9 % Attritional loss ratio - prior year development 0.3 % 0.8 % 0.6 % Catastrophe loss ratio - current year 2.2 % 6.1 % 4.1 % Catastrophe loss ratio - prior year development (0.8) % (1.3) % (1.1) % Loss and loss adjustment expense ratio 56.3 % 58.7 % 57.5 % Acquisition cost ratio 25.2 % 19.9 % 22.6 % Other underwriting expense ratio 13.8 % 5.6 % 9.8 % Combined ratio 95.3 % 84.2 % 89.9 % ($ in thousands) Nine Months Ended September 30, 2023 International Bermuda Corporate Total Gross premiums written $ 832,049 $ 685,198 $ — $ 1,517,247 Net premiums written $ 553,687 $ 563,085 $ — $ 1,116,772 Net premiums earned $ 504,784 $ 447,614 $ — $ 952,398 Third party fee income 7,417 336 — 7,753 Losses and loss adjustment expenses 255,787 263,767 — 519,554 Acquisition costs 131,688 88,844 — 220,532 Other underwriting expenses 89,635 36,607 — 126,242 Underwriting income (loss) $ 35,091 $ 58,732 $ — $ 93,823 Net realized and unrealized gains (losses) on investments 101,881 101,881 Net investment income (loss) 17,719 17,719 Other income (loss), excluding third party fee income 85 85 Net foreign exchange gains (losses) (3,953) (3,953) Corporate expenses (31,833) (31,833) Amortization of intangible assets (7,869) (7,869) Interest expense (16,007) (16,007) Income (loss) before income tax 153,846 Income tax (expense) benefit (6,908) (6,908) Net income (loss) 146,938 Net income (loss) attributable to non-controlling interest 15,076 15,076 Net income (loss) attributable to common shareholders $ 131,862 Key Ratios Attritional loss ratio - current year 52.6 % 50.8 % 51.8 % Attritional loss ratio - prior year development (4.3) % 4.0 % (0.4) % Catastrophe loss ratio - current year 2.2 % 5.4 % 3.7 % Catastrophe loss ratio - prior year development 0.2 % (1.3) % (0.5) % Loss and loss adjustment expense ratio 50.7 % 58.9 % 54.6 % Acquisition cost ratio 26.1 % 19.8 % 23.2 % Other underwriting expense ratio 16.3 % 8.1 % 12.4 % Combined ratio 93.1 % 86.8 % 90.2 % The following table presents gross premiums written by the geographical location of the Company's subsidiaries: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 International Lloyd's of London $ 192,380 $ 189,155 $ 590,339 $ 507,326 Ireland 99,650 96,272 283,776 271,002 U.S. 33,495 21,713 83,866 53,721 Total International 325,525 307,140 957,981 832,049 Bermuda 227,876 166,983 920,664 685,198 Total $ 553,401 $ 474,123 $ 1,878,645 $ 1,517,247

Debt and Credit Facilities

Debt and Credit Facilities	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Debt and Credit Facilities	Debt and Credit Facilities Debt On June 23, 2022, Hamilton Group renewed its unsecured $150 million term loan credit arrangement, as amended from time to time (the "Facility"), with various lenders as arranged by Wells Fargo Securities, LLC. All or a portion of the loan issued under the Facility bears interest at either (a) the Base Rate plus the Applicable Margin or (b) the Adjusted Term Secured Overnight Financing Rate ("SOFR") plus the Applicable Margin, at Hamilton Group's discretion. In the event of default, an additional 2% interest in excess of (a) or (b) will be levied, not to exceed the highest rate permissible under applicable law, and certain types of loans may not be available for borrowing by Hamilton Group under the Facility. The Facility matures on June 23, 2025, unless accelerated pursuant to the terms of the Facility, and it contains usual and customary representations, warranties, conditions and covenants for bank loan facilities of this type. The Facility also contains certain financial covenants which cap the ratio of consolidated debt to capital and require that Hamilton Group maintain a certain minimum consolidated net worth. The net worth requirement is recalculated effective as of the end of each fiscal quarter. As at September 30, 2024, the Company was in compliance with all covenants . The following table presents the gross outstanding loan balance, loan fair value and unamortized loan issuance costs: ($ in thousands) September 30, December 31, Outstanding loan balance $ 150,000 $ 150,000 Loan fair value 150,623 150,981 Unamortized loan issuance costs $ 84 $ 170 Debt issuance costs are amortized over the period during which the Facility is outstanding, as an offset to net investment income (loss). The Company amortized debt issuance costs of less than $0.1 million in each of the three and nine months ended September 30, 2024 and 2023. The Company’s debt is classified as Level 3 within the fair value hierarchy because it is valued using an income approach, which utilizes a discounted cash flow technique that considers the credit profile of the Company. Credit Facilities The Company has several available letter of credit facilities and a revolving loan facility provided by commercial banks. The letter of credit facilities are utilized to provide collateral to reinsureds of Hamilton Re and its affiliates to the extent required under insurance and reinsurance agreements and to support capital requirements at Lloyd’s. On December 5, 2018 and December 27, 2018, Hamilton Re entered into a Master Agreement for Issuance of Payment Instruments and a Facility Letter for Issuance of Payment Instruments respectively, with CitiBank Europe Plc ("CitiBank Europe"), under which CitiBank Europe agreed to provide an uncommitted secured letter of credit facility for the issuance of standby letters of credit or similar instruments in multiple currencies. On August 8, 2023, letter of credit capacity under this facility was increased to $200 million. At all times during which it is a party to the facility, Hamilton Re is obligated to pledge to CitiBank Europe cash and/or securities with a value that equals or exceeds the aggregate face amount of its then-outstanding letters of credit. The Master Agreement contains events of default customary for facilities of this type. In the facility letter, Hamilton Re makes representations and warranties that are customary for facilities of this type and agrees that it will comply with certain informational and other undertakings. On June 23, 2022, Hamilton Group and Hamilton Re amended and restated their unsecured credit agreement with a syndication of lenders (the "Unsecured Facility"). Under the Unsecured Facility, the lenders have agreed to provide up to an aggregate of $415 million of letter of credit capacity for Hamilton Re, up to $150 million of which may be utilized for revolving loans to be issued to Hamilton Group. At September 30, 2024, there were no loan amounts outstanding under this facility. Margin rates reflect contractually agreed rates, which are based on Hamilton Re’s current Financial Strength Rating as assigned by A.M. Best. As of April 30, 2024, letters of credit issued under the facility bear interest at a rate of 137.5 basis points (previously 150 basis points), while revolving loans if issued are subject to a fee of SOFR plus a margin of 162.5 basis points (previously 185 basis points). To the extent such loans are issued, the available letter of credit capacity shall decrease proportionally, such that the aggregate credit exposure for the lenders under the credit agreement is $415 million. Amounts unutilized under the facility are subject to a fee of 17.5 basis points (previously 22.5 basis points). Capacity is provided by Wells Fargo, National Association, Truist Bank, BMO Harris Bank N.A., Commerzbank AG, New York Branch, HSBC Bank USA, N.A., and Barclays Bank PLC. Unless renewed or otherwise terminated in accordance with its terms, the Unsecured Facility is scheduled to terminate on June 23, 2025. On August 12, 2024, Hamilton Re and HIDAC amended their committed letter of credit facility agreement with Bank of Montreal ("BMO"), with Hamilton Group as guarantor, under which BMO agreed to make available a secured letter of credit facility of $50 million for a term that will expire on August 13, 2025. The facility bears a fee of 40 basis points for letters of credit issued and 15 basis points on any unutilized portion of the facility. Effective October 25, 2024, Hamilton Re amended its letter of credit facility agreement with UBS AG ("UBS") under which UBS and certain of its affiliates agreed to make available to Hamilton Re a secured letter of credit facility of $100 million for a term that will expire on October 25, 2025. The facility bears a fee of 140 basis points on the total available capacity. In addition, on October 28, 2024, Hamilton Re amended the unsecured letter of credit facility agreement that it utilizes to provide Funds at Lloyd's ("FAL") ("FAL LOC Facility") to support the FAL requirements of Syndicate 4000. Capacity is provided by Barclays Bank PLC, ING Bank N.V., London Branch, and Bank of Montreal, London Branch. The FAL LOC Facility of $230 million was renewed for an additional one year term that expires on October 28, 2025. The facility bears a fee of 162.5 basis points on the borrowed amount. The Company’s obligations under its credit facilities require Hamilton Group, Hamilton Re and the other parties thereto to comply with various financial and reporting covenants. All applicable entities were in compliance with all such covenants at September 30, 2024. Certain of the Company's credit facilities are secured by pledged interests in the TS Hamilton Fund, the Company's fixed income security portfolio, or cash. The Company’s credit facilities and associated securities pledged, were as follows: ($ in thousands) September 30, Available letter of credit and revolving loan facilities - commitments $ 995,000 Available letter of credit and revolving loan facilities - in use 746,786 Security pledged under letter of credit and revolving loan facilities: Pledged interests in TS Hamilton Fund $ 229,376 Pledged interests in fixed income portfolio 258,701 Cash 5,271 The Company has recognized interest expense related to the above debt and credit facilities of $5.4 million and $5.3 million for the three months ended September 30, 2024 and 2023, respectively, and $17.1 million and $16.0 million for the nine months ended September 30, 2024 and 2023, respectively.

Share Capital

Share Capital	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Share Capital	Share Capital Authorized and Issued Hamilton Group’s share capital is comprised as follows: ($ in thousands, except share information) Authorized: Common shares of $0.01 par value each (2024 and 2023: 150,000,000) Issued, outstanding and fully paid: September 30, December 31, Class A common shares (2024: 17,820,078 and 2023: 28,644,807) $ 178 $ 286 Class B common shares (2024: 63,668,995 and 2023: 56,036,067) 637 560 Class C common shares (2024: 19,903,649 and 2023: 25,544,229) 199 255 Total $ 1,014 $ 1,101 The following is a summary of the activity related to common shares authorized: Class A Class B Class C Unclassified Total Balance - June 30, 2024 28,644,807 72,837,352 25,044,229 23,473,612 150,000,000 Share class conversions (1,700,000) 6,840,580 (5,140,580) — — Balance - September 30, 2024 26,944,807 79,677,932 19,903,649 23,473,612 150,000,000 Class A Class B Class C Unclassified Total Balance - June 30, 2023 53,993,690 50,480,684 30,525,626 — 135,000,000 Increase in authorized share capital — 15,000,000 — — 15,000,000 Balance - September 30, 2023 53,993,690 65,480,684 30,525,626 — 150,000,000 Class A Class B Class C Unclassified Total Balance - December 31, 2023 28,644,807 72,337,352 25,544,229 23,473,612 150,000,000 Share class conversions (1,700,000) 7,340,580 (5,640,580) — — Balance - September 30, 2024 26,944,807 79,677,932 19,903,649 23,473,612 150,000,000 Class A Class B Class C Unclassified Total Balance - December 31, 2022 53,993,690 50,480,684 30,525,626 — 135,000,000 Increase in authorized share capital — 15,000,000 — — 15,000,000 Balance - September 30, 2023 53,993,690 65,480,684 30,525,626 — 150,000,000 The following is a summary of the activity related to common shares issued and outstanding: Class A Class B Class C Total Balance - June 30, 2024 19,520,078 57,358,464 25,044,229 101,922,771 Share class conversions (1,700,000) 6,840,580 (5,140,580) — Share repurchases — (530,049) — (530,049) Balance - September 30, 2024 17,820,078 63,668,995 19,903,649 101,392,722 Class A Class B Class C Total Balance - June 30, 2023 30,520,078 42,638,190 30,525,626 103,683,894 Director share awards granted — 20,112 — 20,112 Balance - September 30, 2023 30,520,078 42,658,302 30,525,626 103,704,006 Class A Class B Class C Total Balance - December 31, 2023 28,644,807 56,036,067 25,544,229 110,225,103 Share class conversions (1,700,000) 7,340,580 (5,640,580) — Vesting of awards — 761,261 — 761,261 Exercise of warrants — 245,779 — 245,779 Director share awards granted — 20,383 — 20,383 Share repurchases (9,124,729) (735,075) — (9,859,804) Balance - September 30, 2024 17,820,078 63,668,995 19,903,649 101,392,722 Class A Class B Class C Total Balance - December 31, 2022 30,520,078 42,042,155 30,525,626 103,087,859 Vesting of awards — 735,013 — 735,013 Director share awards granted — 44,892 — 44,892 Share repurchases — (163,758) — (163,758) Balance - September 30, 2023 30,520,078 42,658,302 30,525,626 103,704,006 On May 8, 2024, the Company entered into an agreement to repurchase 9.1 million Class A common shares at $12.00 per share (the "Share Repurchase"). The total purchase price was $109.5 million. The common shares purchased by the Company were cancelled following the repurchase transaction. On August 7, 2024, the Board of Directors authorized a repurchase of the Company's common shares in the aggregate amount of $150.0 million (the "Authorization"), under which the Company may repurchase shares through open market repurchases and/or privately negotiated transactions. The Authorization will expire when the Company has repurchased the full value of shares authorized, unless terminated earlier by the Board of Directors. In the three months ended September 30, 2024, 0.5 million Class B common shares at an aggregate cost of $10.0 million and an average price of $18.87 per common share were repurchased and cancelled and $140.0 million remained available for purchase under the Authorization. In general, holders of Class A common shares and Class B common shares have one vote for each common share held while the Class C common shares have no voting rights, except as required by law. However, each holder of Class A common shares and Class B common shares is limited to voting (directly, indirectly or constructively, as determined for U.S. federal income tax purposes) that number of common shares equal to 9.5% of the total combined voting power of all classes of shares of the Company (or, in the case of a class vote by the holders of our Class B common shares, such as in respect of the election or removal of directors other than for directors who are appointed by certain shareholders pursuant to the Shareholders Agreement and our Bye-laws, a maximum of 14.92% of the total combined voting power). In addition, the Board of Directors may limit a shareholder’s voting rights when it deems it appropriate to do so to avoid certain material adverse tax, legal or regulatory consequences to the Company or any direct or indirect shareholder or its affiliates. The Company Bye-laws provide for the automatic redesignation of shares upon any transfer, whether or not for value, from (i) Class A common shares to Class B common shares and from (ii) Class C common shares to Class B common shares. Upon notice from a Class A Member to the Company that certain Class B common shares are held by a Class A Member or a Permitted Transferee thereof, if so requested by the Class A Member and upon approval by a Simple Majority of the Board, such Class B common shares shall convert automatically into the same number of Class A common shares. The number of authorized and issued Class B common shares shall be reduced by the aggregate number of such issued Class B common shares so converted and the number of authorized and issued Class A common shares shall be correspondingly increased by the same amount. Upon notice from a Class A Member and/or Class B Member to the Company and upon approval by a Simple Majority of the Board, such consent not to be unreasonably withheld or unduly delayed, such Class A common shares and/or Class B common shares shall be redesignated as Class C common shares. In such instance, the authorized and issued number of Class A common shares and/or Class B common shares shall be reduced by the aggregate number of such shares so converted and the number of Class C common shares shall be correspondingly increased by the same amount. Upon notice from a Class C Member to the Company and upon approval of a Simple Majority of the Board, such consent not to be unreasonably withheld or unduly delayed, such Class C common shares shall be redesignated Class B common shares. In such instance, the authorized and issued number of Class C common shares shall be reduced by the aggregate number of such Class C common shares so converted and the number of authorized and issued Class B common shares shall be correspondingly increased by the same amount. On September 13, 2024, 1.7 million Class A common shares were converted into Class C common shares at the request of the Class A Members and as approved by the Board. During the three and nine months ended September 30, 2024, 6.8 million and 7.3 million, respectively, Class C common shares were converted into Class B common shares at the request of the respective Class C Members and as approved by the Board.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The following table sets forth the computation of basic and diluted income (loss) per common share, respectively: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands, except per share information) 2024 2023 2024 2023 Numerator: Net income (loss) attributable to common shareholders $ 78,250 $ 43,583 $ 366,509 $ 131,862 Denominator: Weighted average common shares outstanding - basic 101,934 103,704 106,240 103,711 Effect of dilutive securities 4,425 1,720 3,986 1,260 Weighted average common shares outstanding - diluted 106,359 105,424 110,226 104,971 Basic income (loss) per share attributable to $ 0.77 $ 0.42 $ 3.45 $ 1.27 Diluted income (loss) per share attributable to $ 0.74 $ 0.41 $ 3.33 $ 1.26 For each of the three and nine months ended September 30, 2024, there were no common shares available for issuance under share-based compensation plans that were excluded from the calculation of diluted income (loss) per share because the assumed exercise or issuance of such shares would be anti-dilutive. For each of the three and nine months ended September 30, 2023, there were no common shares available for issuance under share-based compensation plans that were excluded from the calculation of diluted income (loss) per share because the assumed exercise or issuance of such shares would be anti-dilutive.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Hurricane Milton In October 2024, Hurricane Milton made landfall near Siesta Key, Florida, traveling north-east across the state and into the Atlantic Ocean. The Company estimates that losses from Hurricane Milton, net of reinsurance, will be in the range of $30 million to $70 million. The level of uncertainty within the Company’s loss estimates for Hurricane Milton is increased by the recent occurrence of the event and the preliminary nature of the information available, among other factors. The estimated losses for this event will be reported in the Company's fourth quarter 2024 financial results.

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	9 Months Ended
	Sep. 30, 2024 shares	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Alex Baker [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On September 13, 2024, M r. Alex Baker, Group Chief Risk Officer and an officer of the Company as defined in Rule 16a-1(f) of the Securities Exchange Act of 1934, adopted a trading arrangement for the sale of securities of the Company’s common stock (a “Rule 10b5-1 Trading Plan”), as defined in Regulation S-K, Item 408. Mr. Baker’s Rule 10b5-1 Trading Plan, which has a plan end date of September 2, 2025, pro vides for the sale of up to 24,000 Class B common shares pursuant to
Name	Alex Baker
Title	Group Chief Risk Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 13, 2024
Expiration Date	September 2, 2025
Arrangement Duration	354 days
Aggregate Available	24,000	24,000

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation
Basis of Presentation	These financial statements include the accounts of Hamilton Group, Hamilton Re, Hamilton U.K. Holdings Limited, Hamilton Select, HMGA Americas, ACML, and TS Hamilton Fund (collectively the "Company"). All significant intercompany transactions and balances have been eliminated on consolidation
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported and disclosed amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The major estimates recorded in the Company’s financial statements include, but are not limited to, premiums written, provisions for estimated future credit losses, the reserve for losses and loss adjustment expenses and the fair value of investments.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU 2023-07 Segment Reporting , which enhances the qualitative and quantitative disclosures related to reportable segments. The guidance is effective for annual periods beginning after December 15, 2023 and interim periods beginning after December 15, 2024. Early adoption is permitted. This guidance will not have a material impact on the Company's results of operations, financial position, or cash flows. In December 2023, the FASB issued ASU 2023-09 Income Taxes , which enhances the quantitative annual disclosures related to tax rate reconciliations and income taxes paid and requires additional qualitative discussion of applicable tax jurisdictions and the nature of certain reconciling items. The guidance is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. This guidance will not have a material impact on the Company's results of operations, financial position, or cash flows.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Fixed Maturity and Short-Term Investments	The Company’s fixed maturity and short-term investments are as follows: September 30, 2024 ($ in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturities: U.S. government treasuries $ 761,334 $ 9,273 $ (5,679) $ 764,928 U.S. states, territories and municipalities 13,528 114 (175) 13,467 Non-U.S. sovereign governments and supranationals 74,679 3,029 (532) 77,176 Corporate 1,118,605 24,677 (9,485) 1,133,797 Residential mortgage-backed securities - Agency 258,788 3,069 (10,343) 251,514 Residential mortgage-backed securities - Non-agency 5,790 109 (540) 5,359 Commercial mortgage-backed securities - Non-agency 33,189 535 (615) 33,109 Other asset-backed securities 40,255 660 (81) 40,834 Total fixed maturities 2,306,168 41,466 (27,450) 2,320,184 Short-term investments 506,244 1,709 (6) 507,947 Total $ 2,812,412 $ 43,175 $ (27,456) $ 2,828,131 December 31, 2023 ($ in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturities: U.S. government treasuries $ 717,134 $ 5,137 $ (14,021) $ 708,250 U.S. states, territories and municipalities 4,656 — (286) 4,370 Non-U.S. sovereign governments and supranationals 55,662 2,175 (1,591) 56,246 Corporate 877,493 8,443 (22,060) 863,876 Residential mortgage-backed securities - Agency 180,661 435 (12,583) 168,513 Residential mortgage-backed securities - Non-agency 5,639 16 (671) 4,984 Commercial mortgage-backed securities - Non-agency 11,473 — (1,050) 10,423 Other asset-backed securities 14,781 20 (195) 14,606 Total fixed maturities 1,867,499 16,226 (52,457) 1,831,268 Short-term investments 427,437 1,441 — 428,878 Total $ 2,294,936 $ 17,667 $ (52,457) $ 2,260,146
Schedule of Contractual Maturities of Fixed Maturity Securities	The following table presents contractual maturities of fixed maturity securities. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. September 30, 2024 ($ in thousands) Amortized Cost Fair Value Due less than one year $ 149,305 $ 148,136 Due after one through five years 1,590,516 1,607,936 Due after five through ten years 224,518 229,859 Due after ten years 3,807 3,437 Mortgage-backed securities 297,767 289,982 Asset-backed securities 40,255 40,834 Total $ 2,306,168 $ 2,320,184
Schedule of Investments in Two Sigma Funds	The Company’s investments in Two Sigma Funds are as follows: September 30, 2024 December 31, 2023 ($ in thousands) Cost Net Unrealized Gains (Losses) Fair Value Cost Net Unrealized Gains (Losses) Fair Value Two Sigma Futures Portfolio, LLC (FTV) $ 352,138 $ 7,017 $ 359,155 $ 433,911 $ (38,105) $ 395,806 Two Sigma Spectrum Portfolio, LLC (STV) 337,247 55,581 392,828 193,299 88,228 281,527 Two Sigma Equity Spectrum Portfolio, LLC (ESTV) 140,221 40,583 180,804 142,981 31,156 174,137 Total $ 829,606 $ 103,181 $ 932,787 $ 770,191 $ 81,279 $ 851,470
Schedule of Certain Investments of FTV, STV and ESTV	The following table summarizes certain investments of FTV, STV and ESTV where TS Hamilton Fund’s proportionate share of the fair value of the investment represents more than 5% of TS Hamilton Fund’s members’ equity: September 30, 2024 ($ in thousands) Principal / Shares (1) Fair Value (1) % of Members' Equity State Street Treasury Obligations Money Market Fund 185,175 $ 185,175 9.9 % U.S. Treasury Securities, 0.0000% - 4.2500%, due 10/29/2024 - 8/15/2044 2,049,275 $ 2,073,372 110.3 % State Street Institutional Treasury Plus Money Market Fund 98,599 $ 98,599 5.3 % U.S. Treasury Securities, 3.5000% - 4.2500%, due 9/30/2026 - 8/15/2054 (852,058) $ (850,202) (45.2) % (1)
Schedule of Realized and Unrealized Gains (Losses) on Investments and Net Investment Income (Loss)	The components of total net realized and unrealized gains (losses) on investments and net investment income (loss) are as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Net realized and unrealized gains (losses) on investments: Net realized gains (losses) on investments $ 93,711 $ 42,403 $ 382,646 $ 32,363 Change in net unrealized gains (losses) on investments (45,483) 4,940 72,205 69,518 Net realized and unrealized gains (losses) on investments 48,228 47,343 454,851 101,881 Net investment income (loss): Fixed maturities 22,067 12,208 58,025 31,178 Short-term investments 10 38 50 287 TS Hamilton Fund 3,108 3,121 9,040 13,033 Cash and cash equivalents 4,384 4,029 12,594 8,752 Other 306 (104) 1,473 1,015 Interest and other 29,875 19,292 81,182 54,265 Management fees (12,207) (10,958) (36,640) (35,806) Other expenses (338) (265) (875) (740) Net investment income (loss) 17,330 8,069 43,667 17,719 Total net realized and unrealized gains (losses) on investments and net investment income (loss) $ 65,558 $ 55,412 $ 498,518 $ 119,600
Schedule of Realized Gain (Loss) on Investments	The components of net realized gains (losses) on investments are as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Fixed maturities and short-term investments $ 2,769 $ (7,688) $ (1,866) $ (10,796) TS Hamilton Fund 90,942 50,091 384,228 42,948 Other — — 284 211 Net realized gains (losses) on investments $ 93,711 $ 42,403 $ 382,646 $ 32,363
Schedule of Unrealized Gain (Loss) on Investments	The components of net unrealized gains (losses) on investments are as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Fixed maturities and short-term investments $ 64,903 $ (12,818) $ 50,304 $ (9,800) TS Hamilton Fund (110,386) 17,758 21,901 79,318 Net unrealized gains (losses) on investments $ (45,483) $ 4,940 $ 72,205 $ 69,518

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis	The following table presents the financial instruments measured at fair value on a recurring basis: September 30, 2024 ($ in thousands) Level 1 Level 2 Level 3 Total Fixed maturities: U.S. government treasuries $ — $ 764,928 $ — $ 764,928 U.S. states, territories and municipalities — 13,467 — 13,467 Non-U.S. sovereign governments and supranationals — 77,176 — 77,176 Corporate — 1,133,797 — 1,133,797 Residential mortgage-backed securities - Agency — 251,514 — 251,514 Residential mortgage-backed securities - Non-agency — 5,359 — 5,359 Commercial mortgage-backed securities - Non-agency — 33,109 — 33,109 Other asset-backed securities — 40,834 — 40,834 Total fixed maturities — 2,320,184 — 2,320,184 Short-term investments — 507,947 — 507,947 Total $ — $ 2,828,131 $ — $ 2,828,131 December 31, 2023 ($ in thousands) Level 1 Level 2 Level 3 Total Fixed maturities: U.S. government treasuries $ — $ 708,250 $ — $ 708,250 U.S. states, territories and municipalities — 4,370 — 4,370 Non-U.S. sovereign governments and supranationals — 56,246 — 56,246 Corporate — 863,876 — 863,876 Residential mortgage-backed securities - Agency — 168,513 — 168,513 Residential mortgage-backed securities - Non-agency — 4,984 — 4,984 Commercial mortgage-backed securities - Non-agency — 10,423 — 10,423 Other asset-backed securities — 14,606 — 14,606 Total fixed maturities — 1,831,268 — 1,831,268 Short-term investments — 428,878 — 428,878 Total $ — $ 2,260,146 $ — $ 2,260,146

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Activity In and Total Assets and Total Liabilities of TS Hamilton Fund	Activity in the non-controlling interest of TS Hamilton Fund was as follows: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Balance - beginning of period $ 77,275 $ 124 $ 133 $ 119 Withdrawals — (9,060) (112,313) (15,066) Equity in earnings (1) 5 33 10 Incentive allocation (17,214) 9,060 172,207 15,066 Balance - end of period $ 60,060 $ 129 $ 60,060 $ 129 The following table presents the total assets and total liabilities of TS Hamilton Fund. Creditors or beneficial interest holders of TS Hamilton Fund have no recourse to the general credit of the Company as the Company’s obligation is limited to the amount of its committed investment. ($ in thousands) September 30, December 31, Assets Cash and cash equivalents $ 560,757 $ 479,255 Short-term investments 507,947 428,878 Investments in Two Sigma Funds, at fair value 932,787 851,470 Receivables for investments sold 28,977 41,087 Interest and dividends receivable 1,184 966 Total assets 2,031,652 1,801,656 Liabilities Accounts payable and accrued expenses 190 191 Withdrawal payable — 6,480 Payable for investments purchased 151,754 62,440 Total liabilities 151,944 69,111 Total net assets managed by TS Hamilton Fund $ 1,879,708 $ 1,732,545

Reinsurance (Tables)

Reinsurance (Tables)	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Rollforward of Provision for Current Expected Credit Losses of Premiums Receivable	The following table provides a roll forward of the provision for current expected credit losses of the Company's premiums receivable: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Beginning balance $ 1,962 $ 3,098 $ 3,000 $ 2,856 Increase (decrease) in allowance 46 (356) (992) (114) Ending balance $ 2,008 $ 2,742 $ 2,008 $ 2,742
Rollforward of Provision for Current Expected Credit Losses of Reinsurance Recoverable	The following table provides a roll forward of the provision for current expected credit losses of the Company's reinsurance recoverable: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 Beginning balance $ 755 $ 820 $ 687 $ 777 Increase (decrease) in allowance 78 (129) 146 (86) Ending balance $ 833 $ 691 $ 833 $ 691
Schedule of Paid and Unpaid Losses and Loss Adjustment Expenses Recoverable	The distribution of the Company’s paid losses recoverable and unpaid losses and loss adjustment expenses recoverable as categorized by major rating agencies were as follows: Classification September 30, December 31, Collateralized 24.9 % 28.5 % A- or better 74.9 % 71.0 % Below A- 0.2 % 0.5 % Total 100.0 % 100.0 %

Reserve for Losses and Loss A_2

Reserve for Losses and Loss Adjustment Expenses (Tables)	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Schedule of Reconciliation of Unpaid Losses and Loss Adjustment Expenses	The following table presents a reconciliation of unpaid losses and loss adjustment expenses ("LAE") for the nine months ended September 30, 2024 and 2023: Nine Months Ended September 30, ($ in thousands) 2024 2023 Gross unpaid losses and loss adjustment expenses, beginning of period $ 3,030,037 $ 2,856,275 Reinsurance recoverable on unpaid losses 1,161,077 1,177,863 Net unpaid losses and loss adjustment expenses, beginning of period 1,868,960 1,678,412 Net losses and loss adjustment expenses incurred in respect of losses occurring in: Current year 726,602 528,457 Prior years (6,124) (8,903) Total incurred 720,478 519,554 Net losses and loss adjustment expenses paid in respect of losses occurring in: Current year 24,850 28,521 Prior years 344,992 397,407 Total paid 369,842 425,928 Foreign currency revaluation and other 24,739 19,661 Net unpaid losses and loss adjustment expenses, end of period 2,244,335 1,791,699 Reinsurance recoverable on unpaid losses 1,190,465 1,157,123 Gross unpaid losses and loss adjustment expenses, end of period $ 3,434,800 $ 2,948,822

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	($ in thousands) Three Months Ended September 30, 2024 International Bermuda Corporate Total Gross premiums written $ 325,525 $ 227,876 $ — $ 553,401 Net premiums written $ 268,106 $ 209,790 $ — $ 477,896 Net premiums earned $ 225,244 $ 223,551 $ — $ 448,795 Third party fee income 4,170 294 — 4,464 Losses and loss adjustment expenses 130,135 143,497 — 273,632 Acquisition costs 59,713 42,488 — 102,201 Other underwriting expenses 34,143 14,189 — 48,332 Underwriting income (loss) $ 5,423 $ 23,671 $ — $ 29,094 Net realized and unrealized gains (losses) on investments 48,228 48,228 Net investment income (loss) 17,330 17,330 Net foreign exchange gains (losses) (5,973) (5,973) Corporate expenses (14,060) (14,060) Amortization of intangible assets (5,204) (5,204) Interest expense (5,351) (5,351) Income (loss) before income tax 64,064 Income tax (expense) benefit (3,029) (3,029) Net income (loss) 61,035 Net income (loss) attributable to non-controlling interest (17,215) (17,215) Net income (loss) attributable to common shareholders $ 78,250 Key Ratios Attritional loss ratio - current year 55.3 % 51.0 % 53.2 % Attritional loss ratio - prior year development (1.5) % 0.0 % (0.7) % Catastrophe loss ratio - current year 6.4 % 16.7 % 11.5 % Catastrophe loss ratio - prior year development (2.4) % (3.5) % (3.0) % Loss and loss adjustment expense ratio 57.8 % 64.2 % 61.0 % Acquisition cost ratio 26.5 % 19.0 % 22.8 % Other underwriting expense ratio 13.3 % 6.2 % 9.8 % Combined ratio 97.6 % 89.4 % 93.6 % ($ in thousands) Three Months Ended September 30, 2023 International Bermuda Corporate Total Gross premiums written $ 307,140 $ 166,983 $ — $ 474,123 Net premiums written $ 234,621 $ 148,945 $ — $ 383,566 Net premiums earned $ 178,632 $ 158,404 $ — $ 337,036 Third party fee income 2,115 186 — 2,301 Losses and loss adjustment expenses 97,820 93,757 — 191,577 Acquisition costs 47,236 31,301 — 78,537 Other underwriting expenses 31,634 12,723 — 44,357 Underwriting income (loss) $ 4,057 $ 20,809 $ — $ 24,866 Net realized and unrealized gains (losses) on investments 47,343 47,343 Net investment income (loss) 8,069 8,069 Other income (loss), excluding third party fee income 85 85 Net foreign exchange gains (losses) 1,432 1,432 Corporate expenses (18,678) (18,678) Amortization of intangible assets (2,794) (2,794) Interest expense (5,288) (5,288) Income (loss) before income tax 55,035 Income tax (expense) benefit (2,387) (2,387) Net income (loss) 52,648 Net income (loss) attributable to non-controlling interest 9,065 9,065 Net income (loss) attributable to common shareholders $ 43,583 Key Ratios Attritional loss ratio - current year 54.6 % 55.1 % 54.8 % Attritional loss ratio - prior year development (5.3) % 5.7 % (0.1) % Catastrophe loss ratio - current year 5.1 % 2.6 % 3.9 % Catastrophe loss ratio - prior year development 0.4 % (4.2) % (1.8) % Loss and loss adjustment expense ratio 54.8 % 59.2 % 56.8 % Acquisition cost ratio 26.4 % 19.8 % 23.3 % Other underwriting expense ratio 16.5 % 7.9 % 12.5 % Combined ratio 97.7 % 86.9 % 92.6 % ($ in thousands) Nine Months Ended September 30, 2024 International Bermuda Corporate Total Gross premiums written $ 957,981 $ 920,664 $ — $ 1,878,645 Net premiums written $ 687,444 $ 780,399 $ — $ 1,467,843 Net premiums earned $ 637,700 $ 615,162 $ — $ 1,252,862 Third party fee income 11,557 6,377 — 17,934 Losses and loss adjustment expenses 359,181 361,297 — 720,478 Acquisition costs 160,589 122,470 — 283,059 Other underwriting expenses 99,317 41,022 — 140,339 Underwriting income (loss) $ 30,170 $ 96,750 $ — $ 126,920 Net realized and unrealized gains (losses) on investments 454,851 454,851 Net investment income (loss) 43,667 43,667 Net foreign exchange gains (losses) (9,883) (9,883) Corporate expenses (41,825) (41,825) Amortization of intangible assets (11,773) (11,773) Interest expense (17,090) (17,090) Income (loss) before income tax 544,867 Income tax (expense) benefit (6,118) (6,118) Net income (loss) 538,749 Net income (loss) attributable to non-controlling interest 172,240 172,240 Net income (loss) attributable to common shareholders $ 366,509 Key Ratios Attritional loss ratio - current year 54.6 % 53.1 % 53.9 % Attritional loss ratio - prior year development 0.3 % 0.8 % 0.6 % Catastrophe loss ratio - current year 2.2 % 6.1 % 4.1 % Catastrophe loss ratio - prior year development (0.8) % (1.3) % (1.1) % Loss and loss adjustment expense ratio 56.3 % 58.7 % 57.5 % Acquisition cost ratio 25.2 % 19.9 % 22.6 % Other underwriting expense ratio 13.8 % 5.6 % 9.8 % Combined ratio 95.3 % 84.2 % 89.9 % ($ in thousands) Nine Months Ended September 30, 2023 International Bermuda Corporate Total Gross premiums written $ 832,049 $ 685,198 $ — $ 1,517,247 Net premiums written $ 553,687 $ 563,085 $ — $ 1,116,772 Net premiums earned $ 504,784 $ 447,614 $ — $ 952,398 Third party fee income 7,417 336 — 7,753 Losses and loss adjustment expenses 255,787 263,767 — 519,554 Acquisition costs 131,688 88,844 — 220,532 Other underwriting expenses 89,635 36,607 — 126,242 Underwriting income (loss) $ 35,091 $ 58,732 $ — $ 93,823 Net realized and unrealized gains (losses) on investments 101,881 101,881 Net investment income (loss) 17,719 17,719 Other income (loss), excluding third party fee income 85 85 Net foreign exchange gains (losses) (3,953) (3,953) Corporate expenses (31,833) (31,833) Amortization of intangible assets (7,869) (7,869) Interest expense (16,007) (16,007) Income (loss) before income tax 153,846 Income tax (expense) benefit (6,908) (6,908) Net income (loss) 146,938 Net income (loss) attributable to non-controlling interest 15,076 15,076 Net income (loss) attributable to common shareholders $ 131,862 Key Ratios Attritional loss ratio - current year 52.6 % 50.8 % 51.8 % Attritional loss ratio - prior year development (4.3) % 4.0 % (0.4) % Catastrophe loss ratio - current year 2.2 % 5.4 % 3.7 % Catastrophe loss ratio - prior year development 0.2 % (1.3) % (0.5) % Loss and loss adjustment expense ratio 50.7 % 58.9 % 54.6 % Acquisition cost ratio 26.1 % 19.8 % 23.2 % Other underwriting expense ratio 16.3 % 8.1 % 12.4 % Combined ratio 93.1 % 86.8 % 90.2 %
Schedule of Revenue from External Customers by Geographic Areas	The following table presents gross premiums written by the geographical location of the Company's subsidiaries: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands) 2024 2023 2024 2023 International Lloyd's of London $ 192,380 $ 189,155 $ 590,339 $ 507,326 Ireland 99,650 96,272 283,776 271,002 U.S. 33,495 21,713 83,866 53,721 Total International 325,525 307,140 957,981 832,049 Bermuda 227,876 166,983 920,664 685,198 Total $ 553,401 $ 474,123 $ 1,878,645 $ 1,517,247

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	9 Months Ended
	Sep. 30, 2024
Debt Disclosure [Abstract]
Schedule of Long-Term Debt Instruments	The following table presents the gross outstanding loan balance, loan fair value and unamortized loan issuance costs: ($ in thousands) September 30, December 31, Outstanding loan balance $ 150,000 $ 150,000 Loan fair value 150,623 150,981 Unamortized loan issuance costs $ 84 $ 170
Schedule of Credit Facilities	The Company’s credit facilities and associated securities pledged, were as follows: ($ in thousands) September 30, Available letter of credit and revolving loan facilities - commitments $ 995,000 Available letter of credit and revolving loan facilities - in use 746,786 Security pledged under letter of credit and revolving loan facilities: Pledged interests in TS Hamilton Fund $ 229,376 Pledged interests in fixed income portfolio 258,701 Cash 5,271

Share Capital (Tables)

Share Capital (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Schedule of Share Capital	Hamilton Group’s share capital is comprised as follows: ($ in thousands, except share information) Authorized: Common shares of $0.01 par value each (2024 and 2023: 150,000,000) Issued, outstanding and fully paid: September 30, December 31, Class A common shares (2024: 17,820,078 and 2023: 28,644,807) $ 178 $ 286 Class B common shares (2024: 63,668,995 and 2023: 56,036,067) 637 560 Class C common shares (2024: 19,903,649 and 2023: 25,544,229) 199 255 Total $ 1,014 $ 1,101
Schedule of Activity Related to Common Shares	The following is a summary of the activity related to common shares authorized: Class A Class B Class C Unclassified Total Balance - June 30, 2024 28,644,807 72,837,352 25,044,229 23,473,612 150,000,000 Share class conversions (1,700,000) 6,840,580 (5,140,580) — — Balance - September 30, 2024 26,944,807 79,677,932 19,903,649 23,473,612 150,000,000 Class A Class B Class C Unclassified Total Balance - June 30, 2023 53,993,690 50,480,684 30,525,626 — 135,000,000 Increase in authorized share capital — 15,000,000 — — 15,000,000 Balance - September 30, 2023 53,993,690 65,480,684 30,525,626 — 150,000,000 Class A Class B Class C Unclassified Total Balance - December 31, 2023 28,644,807 72,337,352 25,544,229 23,473,612 150,000,000 Share class conversions (1,700,000) 7,340,580 (5,640,580) — — Balance - September 30, 2024 26,944,807 79,677,932 19,903,649 23,473,612 150,000,000 Class A Class B Class C Unclassified Total Balance - December 31, 2022 53,993,690 50,480,684 30,525,626 — 135,000,000 Increase in authorized share capital — 15,000,000 — — 15,000,000 Balance - September 30, 2023 53,993,690 65,480,684 30,525,626 — 150,000,000 The following is a summary of the activity related to common shares issued and outstanding: Class A Class B Class C Total Balance - June 30, 2024 19,520,078 57,358,464 25,044,229 101,922,771 Share class conversions (1,700,000) 6,840,580 (5,140,580) — Share repurchases — (530,049) — (530,049) Balance - September 30, 2024 17,820,078 63,668,995 19,903,649 101,392,722 Class A Class B Class C Total Balance - June 30, 2023 30,520,078 42,638,190 30,525,626 103,683,894 Director share awards granted — 20,112 — 20,112 Balance - September 30, 2023 30,520,078 42,658,302 30,525,626 103,704,006 Class A Class B Class C Total Balance - December 31, 2023 28,644,807 56,036,067 25,544,229 110,225,103 Share class conversions (1,700,000) 7,340,580 (5,640,580) — Vesting of awards — 761,261 — 761,261 Exercise of warrants — 245,779 — 245,779 Director share awards granted — 20,383 — 20,383 Share repurchases (9,124,729) (735,075) — (9,859,804) Balance - September 30, 2024 17,820,078 63,668,995 19,903,649 101,392,722 Class A Class B Class C Total Balance - December 31, 2022 30,520,078 42,042,155 30,525,626 103,087,859 Vesting of awards — 735,013 — 735,013 Director share awards granted — 44,892 — 44,892 Share repurchases — (163,758) — (163,758) Balance - September 30, 2023 30,520,078 42,658,302 30,525,626 103,704,006

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2024
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Income (Loss) per Common Share	The following table sets forth the computation of basic and diluted income (loss) per common share, respectively: Three Months Ended Nine Months Ended September 30, September 30, ($ in thousands, except per share information) 2024 2023 2024 2023 Numerator: Net income (loss) attributable to common shareholders $ 78,250 $ 43,583 $ 366,509 $ 131,862 Denominator: Weighted average common shares outstanding - basic 101,934 103,704 106,240 103,711 Effect of dilutive securities 4,425 1,720 3,986 1,260 Weighted average common shares outstanding - diluted 106,359 105,424 110,226 104,971 Basic income (loss) per share attributable to $ 0.77 $ 0.42 $ 3.45 $ 1.27 Diluted income (loss) per share attributable to $ 0.74 $ 0.41 $ 3.33 $ 1.26

Organization (Details)

Organization (Details) - Two Sigma Hamilton Fund, LLC - Hamilton Re - USD ($) $ in Billions	Jul. 01, 2023	Jun. 30, 2023
Schedule of Equity Method Investments [Line Items]
Commitment for investment in Two Sigma Funds	$ 1.8
Investment in Two Sigma Funds, as a percentage of net tangible assets	60%	95%

Investments - Schedule of Fixed

Investments - Schedule of Fixed Maturity and Short-Term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 2,812,412	$ 2,294,936
Gross Unrealized Gains	43,175	17,667
Gross Unrealized Losses	(27,456)	(52,457)
Investments, at fair value	2,828,131	2,260,146
Total fixed maturities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	2,306,168	1,867,499
Gross Unrealized Gains	41,466	16,226
Gross Unrealized Losses	(27,450)	(52,457)
Investments, at fair value	2,320,184	1,831,268
U.S. government treasuries
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	761,334	717,134
Gross Unrealized Gains	9,273	5,137
Gross Unrealized Losses	(5,679)	(14,021)
Investments, at fair value	764,928	708,250
U.S. states, territories and municipalities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	13,528	4,656
Gross Unrealized Gains	114	0
Gross Unrealized Losses	(175)	(286)
Investments, at fair value	13,467	4,370
Non-U.S. sovereign governments and supranationals
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	74,679	55,662
Gross Unrealized Gains	3,029	2,175
Gross Unrealized Losses	(532)	(1,591)
Investments, at fair value	77,176	56,246
Corporate
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,118,605	877,493
Gross Unrealized Gains	24,677	8,443
Gross Unrealized Losses	(9,485)	(22,060)
Investments, at fair value	1,133,797	863,876
Residential mortgage-backed securities - Agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	258,788	180,661
Gross Unrealized Gains	3,069	435
Gross Unrealized Losses	(10,343)	(12,583)
Investments, at fair value	251,514	168,513
Residential mortgage-backed securities - Non-agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	5,790	5,639
Gross Unrealized Gains	109	16
Gross Unrealized Losses	(540)	(671)
Investments, at fair value	5,359	4,984
Commercial mortgage-backed securities - Non-agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	33,189	11,473
Gross Unrealized Gains	535	0
Gross Unrealized Losses	(615)	(1,050)
Investments, at fair value	33,109	10,423
Other asset-backed securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	40,255	14,781
Gross Unrealized Gains	660	20
Gross Unrealized Losses	(81)	(195)
Investments, at fair value	40,834	14,606
Short-term investments
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	506,244	427,437
Gross Unrealized Gains	1,709	1,441
Gross Unrealized Losses	(6)	0
Investments, at fair value	$ 507,947	$ 428,878

Investments - Schedule of Contr

Investments - Schedule of Contractual Maturities of Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Amortized Cost
Amortized Cost	$ 2,812,412	$ 2,294,936
Fair Value
Fair Value	2,828,131	2,260,146
Total fixed maturities
Amortized Cost
Amortized Cost	2,306,168	1,867,499
Fair Value
Fair Value	2,320,184	$ 1,831,268
Fixed Maturities, Excluding Mortgage-backed and Asset-backed Securities
Amortized Cost
Due less than one year	149,305
Due after one through five years	1,590,516
Due after five through ten years	224,518
Due after ten years	3,807
Fair Value
Due less than one year	148,136
Due after one through five years	1,607,936
Due after five through ten years	229,859
Due after ten years	3,437
Mortgage-backed securities
Amortized Cost
Mortgage/Asset-backed	297,767
Fair Value
Mortgage/Asset-backed	289,982
Asset-backed securities
Amortized Cost
Mortgage/Asset-backed	40,255
Fair Value
Mortgage/Asset-backed	$ 40,834

Investments - Schedule of Inves

Investments - Schedule of Investments in Two Sigma Funds (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Marketable Securities [Line Items]
Cost	$ 829,606	$ 770,191
Investments in Two Sigma Funds, at fair value	932,787	851,470
Two Sigma Funds
Marketable Securities [Line Items]
Net Unrealized Gains (Losses)	103,181	81,279
Investments in Two Sigma Funds, at fair value	932,787	851,470
Two Sigma Futures Portfolio, LLC (FTV)
Marketable Securities [Line Items]
Cost	352,138	433,911
Net Unrealized Gains (Losses)	7,017	(38,105)
Investments in Two Sigma Funds, at fair value	359,155	395,806
Two Sigma Spectrum Portfolio, LLC (STV)
Marketable Securities [Line Items]
Cost	337,247	193,299
Net Unrealized Gains (Losses)	55,581	88,228
Investments in Two Sigma Funds, at fair value	392,828	281,527
Two Sigma Equity Spectrum Portfolio, LLC (ESTV)
Marketable Securities [Line Items]
Cost	140,221	142,981
Net Unrealized Gains (Losses)	40,583	31,156
Investments in Two Sigma Funds, at fair value	$ 180,804	$ 174,137

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended	9 Months Ended
	Jul. 01, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Net Investment Income [Line Items]
Management fees		$ 12,207	$ 10,958		$ 36,640	$ 35,806
Restricted cash and cash equivalents		93,883			93,883		$ 106,351
Cash, cash equivalents and restricted cash		1,051,255	903,527		1,051,255	903,527	900,860	$ 1,207,203
Cash and cash equivalents		957,372			957,372		794,509
Capital Requirements | Asset Pledged as Collateral
Net Investment Income [Line Items]
Investments, fair value		250,300			250,300		232,200
Restricted cash and cash equivalents		2,700			2,700		7,200
Trust Accounts | Asset Pledged as Collateral
Net Investment Income [Line Items]
Investments, fair value		89,100			89,100		54,100
Restricted cash and cash equivalents		1,600			1,600		1,500
Underwriting Obligations | Asset Pledged as Collateral
Net Investment Income [Line Items]
Investments, fair value		32,500			32,500		37,200
Restricted cash and cash equivalents		89,600			89,600		97,400
Escrow Funds | Asset Pledged as Collateral
Net Investment Income [Line Items]
Restricted cash and cash equivalents		0			0		300
TS Hamilton Fund
Net Investment Income [Line Items]
Management fee percentage	2.50%			3%
Management fees		11,800	10,400		35,000	34,400
Incentive allocation	30%
Incentive allocation, reduction (as a percent)	50%
Incentive allocation, cumulative net profits (as a percent)	200%
Incentive allocation, excess profits (as a percent)	25%			20%
Incentive allocation, net profits (as a percent)	10%			15%
Incentive allocation expense (income)		(17,200)	$ 9,100		172,200	$ 15,100
Cash and cash equivalents		$ 560,757			$ 560,757		$ 479,255
TS Hamilton Fund | Hamilton Re
Net Investment Income [Line Items]
Initial term		3 years			3 years
Capital account withdrawal, monthly liquidity, number of calendar days prior to month end		15 days			15 days
Capital account withdrawal, daily liquidity, number of business day's written notice		1 day			1 day
Two Sigma Futures Portfolio, LLC (FTV)
Net Investment Income [Line Items]
Percentage of ownership in funds		18.50%			18.50%
Two Sigma Spectrum Portfolio, LLC (STV)
Net Investment Income [Line Items]
Percentage of ownership in funds		17.90%			17.90%
Two Sigma Equity Spectrum Portfolio, LLC (ESTV)
Net Investment Income [Line Items]
Percentage of ownership in funds		9.80%			9.80%
Two Sigma Hamilton Fund, LLC | Hamilton Re
Net Investment Income [Line Items]
Commitment for investment in Two Sigma Funds	$ 1,800,000
Investment in Two Sigma Funds, as a percentage of net tangible assets	60%			95%

Investments - Schedule of Certa

Investments - Schedule of Certain Investments (Details) - USD ($) shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Net Investment Income [Line Items]
Investments in Two Sigma Funds, at fair value	$ 932,787	$ 851,470
TS Hamilton Fund
Net Investment Income [Line Items]
Investments in Two Sigma Funds, at fair value	$ 932,787	$ 851,470
State Street Treasury Obligations Money Market Fund | TS Hamilton Fund | Long
Net Investment Income [Line Items]
Principal / Shares	185,175
Investments in Two Sigma Funds, at fair value	$ 185,175
State Street Treasury Obligations Money Market Fund | Members' Equity | Investment Concentration Risk | TS Hamilton Fund | Long
Net Investment Income [Line Items]
% of Members' Equity	9.90%
U.S. Treasury Securities, 0.0000% - 4.2500%, due 10/29/2024 - 8/15/2044 | TS Hamilton Fund | Long
Net Investment Income [Line Items]
Principal / Shares	2,049,275
Investments in Two Sigma Funds, at fair value	$ 2,073,372
U.S. Treasury Securities, 0.0000% - 4.2500%, due 10/29/2024 - 8/15/2044 | Members' Equity | Investment Concentration Risk | TS Hamilton Fund | Long
Net Investment Income [Line Items]
% of Members' Equity	110.30%
State Street Institutional Treasury Plus Money Market Fund | TS Hamilton Fund | Long
Net Investment Income [Line Items]
Principal / Shares	98,599
Investments in Two Sigma Funds, at fair value	$ 98,599
State Street Institutional Treasury Plus Money Market Fund | Members' Equity | Investment Concentration Risk | TS Hamilton Fund | Long
Net Investment Income [Line Items]
% of Members' Equity	5.30%
U.S. Treasury Securities, 3.5000% - 4.2500%, due 9/30/2026 - 8/15/2054 | TS Hamilton Fund | Short
Net Investment Income [Line Items]
Principal / Shares	852,058
Investments in Two Sigma Funds, at fair value	$ 850,202
U.S. Treasury Securities, 3.5000% - 4.2500%, due 9/30/2026 - 8/15/2054 | Members' Equity | Investment Concentration Risk | TS Hamilton Fund | Short
Net Investment Income [Line Items]
% of Members' Equity	45.20%

Investments - Schedule of Reali

Investments - Schedule of Realized and Unrealized Gains (Losses) on Investments and Net Investment Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net realized and unrealized gains (losses) on investments:
Net realized gains (losses) on investments	$ 93,711	$ 42,403	$ 382,646	$ 32,363
Change in net unrealized gains (losses) on investments	(45,483)	4,940	72,205	69,518
Net realized and unrealized gains (losses) on investments	48,228	47,343	454,851	101,881
Net investment income (loss):
Interest and other	29,875	19,292	81,182	54,265
Management fees	(12,207)	(10,958)	(36,640)	(35,806)
Other expenses	(338)	(265)	(875)	(740)
Net investment income (loss)	17,330	8,069	43,667	17,719
Total net realized and unrealized gains (losses) on investments and net investment income (loss)	65,558	55,412	498,518	119,600
Total fixed maturities
Net investment income (loss):
Interest and other	22,067	12,208	58,025	31,178
Short-term investments
Net investment income (loss):
Interest and other	10	38	50	287
TS Hamilton Fund
Net realized and unrealized gains (losses) on investments:
Net realized gains (losses) on investments	90,942	50,091	384,228	42,948
Change in net unrealized gains (losses) on investments	(110,386)	17,758	21,901	79,318
Net investment income (loss):
Interest and other	3,108	3,121	9,040	13,033
Cash and cash equivalents
Net investment income (loss):
Interest and other	4,384	4,029	12,594	8,752
Other
Net investment income (loss):
Interest and other	306	(104)	1,473	1,015
Fixed maturities and short-term investments
Net realized and unrealized gains (losses) on investments:
Net realized gains (losses) on investments	2,769	(7,688)	(1,866)	(10,796)
Change in net unrealized gains (losses) on investments	64,903	(12,818)	50,304	(9,800)
Other
Net realized and unrealized gains (losses) on investments:
Net realized gains (losses) on investments	$ 0	$ 0	$ 284	$ 211

Fair Value (Details)

Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	$ 2,828,131	$ 2,260,146
Total fixed maturities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	2,320,184	1,831,268
U.S. government treasuries
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	764,928	708,250
U.S. states, territories and municipalities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	13,467	4,370
Non-U.S. sovereign governments and supranationals
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	77,176	56,246
Corporate
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	1,133,797	863,876
Residential mortgage-backed securities - Agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	251,514	168,513
Residential mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	5,359	4,984
Commercial mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	33,109	10,423
Other asset-backed securities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	40,834	14,606
Short-term investments
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	507,947	428,878
Level 1
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Total fixed maturities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | U.S. government treasuries
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | U.S. states, territories and municipalities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Non-U.S. sovereign governments and supranationals
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Corporate
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Residential mortgage-backed securities - Agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Residential mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Commercial mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Other asset-backed securities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 1 | Short-term investments
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 2
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	2,828,131	2,260,146
Level 2 | Total fixed maturities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	2,320,184	1,831,268
Level 2 | U.S. government treasuries
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	764,928	708,250
Level 2 | U.S. states, territories and municipalities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	13,467	4,370
Level 2 | Non-U.S. sovereign governments and supranationals
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	77,176	56,246
Level 2 | Corporate
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	1,133,797	863,876
Level 2 | Residential mortgage-backed securities - Agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	251,514	168,513
Level 2 | Residential mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	5,359	4,984
Level 2 | Commercial mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	33,109	10,423
Level 2 | Other asset-backed securities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	40,834	14,606
Level 2 | Short-term investments
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	507,947	428,878
Level 3
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Total fixed maturities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | U.S. government treasuries
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | U.S. states, territories and municipalities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Non-U.S. sovereign governments and supranationals
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Corporate
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Residential mortgage-backed securities - Agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Residential mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Commercial mortgage-backed securities - Non-agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Other asset-backed securities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	0	0
Level 3 | Short-term investments
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	$ 0	$ 0

Variable Interest Entities - Sc

Variable Interest Entities - Schedule of Activity in the Non-Controlling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Balance - beginning of period			$ 133
Balance - end of period	$ 60,060		60,060
TS Hamilton Fund
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Balance - beginning of period	77,275	$ 124	133	$ 119
Withdrawals	0	(9,060)	(112,313)	(15,066)
Equity in earnings	(1)	5	33	10
Incentive allocation	(17,214)	9,060	172,207	15,066
Balance - end of period	$ 60,060	$ 129	$ 60,060	$ 129

Variable Interest Entities - _2

Variable Interest Entities - Schedule of Total Assets and Total Liabilities of TS Hamilton Fund (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets
Cash and cash equivalents	$ 957,372	$ 794,509
Short-term investments	2,828,131	2,260,146
Investments in Two Sigma Funds, at fair value	932,787	851,470
Receivables for investments sold	39,079	42,419
Total assets	7,826,547	6,671,355
Liabilities
Accounts payable and accrued expenses	168,658	186,887
Payables for investments purchased	172,905	66,606
Total liabilities	5,452,861	4,623,372
Short-term investments
Assets
Short-term investments	507,947	428,878
TS Hamilton Fund
Assets
Cash and cash equivalents	560,757	479,255
Investments in Two Sigma Funds, at fair value	932,787	851,470
Receivables for investments sold	28,977	41,087
Interest and dividends receivable	1,184	966
Total assets	2,031,652	1,801,656
Liabilities
Accounts payable and accrued expenses	190	191
Withdrawal payable	0	6,480
Payables for investments purchased	151,754	62,440
Total liabilities	151,944	69,111
Total net assets managed by TS Hamilton Fund	1,879,708	1,732,545
TS Hamilton Fund | Short-term investments
Assets
Short-term investments	$ 507,947	$ 428,878

Value Appreciation Pool (Detail

Value Appreciation Pool (Details) - Value Appreciation Pool - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Percent of increase in Company fair market value awarded to employees	10%			10%
VAP expense	$ 1.9	$ 11.2		$ 7.5	$ 15.6
Share compensation expense			$ 4.2
Vesting upon trigger event, First anniversary
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting percentage				50%
Vesting upon trigger event, Second anniversary
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Vesting percentage				50%

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 06, 2020	Dec. 31, 2023	Dec. 31, 2020	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2022
Ceded Credit Risk [Line Items]
Premiums receivable balance, credit provisions		$ 3,000		$ 2,008	$ 2,742	$ 2,008	$ 2,742	$ 3,000	$ 1,962	$ 3,098	$ 2,856
Premiums receivable		658,363		885,744		885,744		658,363
Paid losses recoverable		145,202		146,008		146,008		145,202
Unpaid losses and loss adjustment expenses recoverable		1,161,077		1,190,465	1,157,123	1,190,465	1,157,123	1,161,077			1,177,863
Reinsurance recoverable, provisions		687		833	691	833	691	687	$ 755	$ 820	$ 777
Reinsurance premiums ceded				75,505	90,557	410,802	400,475
Related Party
Ceded Credit Risk [Line Items]
Reinsurance premiums ceded				0	0	14,600	7,200
Risk transfer capacity		200,000	$ 150,000
Reinsurance Contract [Axis]: Loss Portfolio Transfer Agreement
Ceded Credit Risk [Line Items]
Unpaid losses and loss adjustment expenses recoverable		$ 49,800		44,200		44,200		$ 49,800
Reinsurance premiums ceded	$ 72,100
Amortization of the deferred gain				$ (600)	$ (900)	$ 1,300	$ 2,500
Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						100%		100%
Reinsurer One | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						24%		27%
Reinsurer Two | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						21%		20%
Reinsurer Three | Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable						13%		12%

Reinsurance - Schedule of Rollf

Reinsurance - Schedule of Rollforward of Provision of Company's Premiums Receivable (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule of Accounts, Notes, Loans and Financing Receivable [Rollforward]
Beginning balance	$ 1,962	$ 3,098	$ 3,000	$ 2,856
Increase (decrease) in allowance	46	(356)	(992)	(114)
Ending balance	$ 2,008	$ 2,742	$ 2,008	$ 2,742

Reinsurance - Schedule of Rol_2

Reinsurance - Schedule of Rollforward of Provision of Company's Reinsurance Recoverable (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule of Accounts, Notes, Loans and Financing Receivable [Rollforward]
Beginning balance	$ 755	$ 820	$ 687	$ 777
Increase (decrease) in allowance	78	(129)	146	(86)
Ending balance	$ 833	$ 691	$ 833	$ 691

Reinsurance - Schedule of Paid

Reinsurance - Schedule of Paid and Unpaid Losses and Loss Adjustment Expenses Recoverable (Details) - Reinsurance Recoverable for Paid and Unpaid Claims and Claims Adjustments - Reinsurer Concentration Risk	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable	100%	100%
A- or better
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable	74.90%	71%
Below A-
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable	0.20%	0.50%
Collateralized
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable	24.90%	28.50%

Reserve for Losses and Loss A_3

Reserve for Losses and Loss Adjustment Expenses - Schedule of Reconciliation of Unpaid Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross unpaid losses and loss adjustment expenses, beginning of period			$ 3,030,037	$ 2,856,275
Reinsurance recoverable on unpaid losses			1,161,077	1,177,863
Net unpaid losses and loss adjustment expenses, beginning of period			1,868,960	1,678,412
Net losses and loss adjustment expenses incurred in respect of losses occurring in:
Current year			726,602	528,457
Prior years			(6,124)	(8,903)
Total incurred	$ 273,632	$ 191,577	720,478	519,554
Net losses and loss adjustment expenses paid in respect of losses occurring in:
Current year			24,850	28,521
Prior years			344,992	397,407
Total paid			369,842	425,928
Foreign currency revaluation and other			24,739	19,661
Net unpaid losses and loss adjustment expenses, end of period	2,244,335	1,791,699	2,244,335	1,791,699
Reinsurance recoverable on unpaid losses	1,190,465	1,157,123	1,190,465	1,157,123
Gross unpaid losses and loss adjustment expenses, end of period	$ 3,434,800	$ 2,948,822	$ 3,434,800	$ 2,948,822

Reserve for Losses and Loss A_4

Reserve for Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)			$ (6,124)	$ (8,903)
Acquisition costs	$ 102,201	$ 78,537	283,059	220,532
Reserve for losses and loss adjustment expenses	3,434,800	2,948,822	3,434,800	2,948,822	$ 3,030,037	$ 2,856,275
Hurricane Helene
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expenses	33,900		33,900		0
Baltimore Bridge
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expenses	37,900		37,900		0
Ukrainian Conflict
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expenses	63,700		63,700		64,900
Covid-19
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expenses	15,600		15,600		$ 14,100
Specialty Contracts
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)			9,500	(20,300)
Casualty Lines
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)			13,200	8,800
Property Contracts
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)			(26,100)	6,600
Casualty Lines of Business | Reinsurance Contract [Axis]: Loss Portfolio Transfer Agreement
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)			(2,700)	(4,000)
Amortization of the associated deferred gain			(1,300)	(2,500)
Net unfavorable (favorable) development in the underlying reserves	$ (1,400)	$ (1,500)	(1,400)	(1,500)
Attritional Losses
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)			7,100	(4,000)
Catastrophe Losses
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)			$ (13,200)	$ (4,900)

Segment Reporting - Schedule of

Segment Reporting - Schedule of Segment Reporting Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Gross premiums written	$ 553,401	$ 474,123	$ 1,878,645	$ 1,517,247
Net premiums written	477,896	383,566	1,467,843	1,116,772
Net premiums earned	448,795	337,036	1,252,862	952,398
Third party fee income	4,464	2,301	17,934	7,753
Losses and loss adjustment expenses	273,632	191,577	720,478	519,554
Acquisition costs	102,201	78,537	283,059	220,532
Other underwriting expenses	48,332	44,357	140,339	126,242
Underwriting income (loss)	29,094	24,866	126,920	93,823
Net realized and unrealized gains (losses) on investments	48,228	47,343	454,851	101,881
Net investment income (loss)	17,330	8,069	43,667	17,719
Other income (loss), excluding third party fee income		85		85
Net foreign exchange gains (losses)	(5,973)	1,432	(9,883)	(3,953)
Corporate expenses	(14,060)	(18,678)	(41,825)	(31,833)
Amortization of intangible assets	(5,204)	(2,794)	(11,773)	(7,869)
Interest expense	(5,351)	(5,288)	(17,090)	(16,007)
Income (loss) before income tax	64,064	55,035	544,867	153,846
Income tax expense (benefit)	(3,029)	(2,387)	(6,118)	(6,908)
Net income (loss)	61,035	52,648	538,749	146,938
Net income (loss) attributable to non-controlling interest	(17,215)	9,065	172,240	15,076
Net income (loss) and other comprehensive income (loss) attributable to common shareholders	$ 78,250	$ 43,583	$ 366,509	$ 131,862
Attritional loss ratio - current year	53.20%	54.80%	53.90%	51.80%
Attritional loss ratio - prior year development	(0.70%)	(0.10%)	0.60%	(0.40%)
Catastrophe loss ratio - current year	11.50%	3.90%	4.10%	3.70%
Catastrophe loss ratio - prior year development	(3.00%)	(1.80%)	(1.10%)	(0.50%)
Loss and loss adjustment expense ratio	61%	56.80%	57.50%	54.60%
Acquisition cost ratio	22.80%	23.30%	22.60%	23.20%
Other underwriting expense ratio	9.80%	12.50%	9.80%	12.40%
Combined ratio	93.60%	92.60%	89.90%	90.20%
Operating Segments | International
Segment Reporting Information [Line Items]
Gross premiums written	$ 325,525	$ 307,140	$ 957,981	$ 832,049
Net premiums written	268,106	234,621	687,444	553,687
Net premiums earned	225,244	178,632	637,700	504,784
Third party fee income	4,170	2,115	11,557	7,417
Losses and loss adjustment expenses	130,135	97,820	359,181	255,787
Acquisition costs	59,713	47,236	160,589	131,688
Other underwriting expenses	34,143	31,634	99,317	89,635
Underwriting income (loss)	$ 5,423	$ 4,057	$ 30,170	$ 35,091
Attritional loss ratio - current year	55.30%	54.60%	54.60%	52.60%
Attritional loss ratio - prior year development	(1.50%)	(5.30%)	0.30%	(4.30%)
Catastrophe loss ratio - current year	6.40%	5.10%	2.20%	2.20%
Catastrophe loss ratio - prior year development	(2.40%)	0.40%	(0.80%)	0.20%
Loss and loss adjustment expense ratio	57.80%	54.80%	56.30%	50.70%
Acquisition cost ratio	26.50%	26.40%	25.20%	26.10%
Other underwriting expense ratio	13.30%	16.50%	13.80%	16.30%
Combined ratio	97.60%	97.70%	95.30%	93.10%
Operating Segments | Bermuda
Segment Reporting Information [Line Items]
Gross premiums written	$ 227,876	$ 166,983	$ 920,664	$ 685,198
Net premiums written	209,790	148,945	780,399	563,085
Net premiums earned	223,551	158,404	615,162	447,614
Third party fee income	294	186	6,377	336
Losses and loss adjustment expenses	143,497	93,757	361,297	263,767
Acquisition costs	42,488	31,301	122,470	88,844
Other underwriting expenses	14,189	12,723	41,022	36,607
Underwriting income (loss)	$ 23,671	$ 20,809	$ 96,750	$ 58,732
Attritional loss ratio - current year	51%	55.10%	53.10%	50.80%
Attritional loss ratio - prior year development	0%	5.70%	0.80%	4%
Catastrophe loss ratio - current year	16.70%	2.60%	6.10%	5.40%
Catastrophe loss ratio - prior year development	(3.50%)	(4.20%)	(1.30%)	(1.30%)
Loss and loss adjustment expense ratio	64.20%	59.20%	58.70%	58.90%
Acquisition cost ratio	19%	19.80%	19.90%	19.80%
Other underwriting expense ratio	6.20%	7.90%	5.60%	8.10%
Combined ratio	89.40%	86.90%	84.20%	86.80%
Corporate
Segment Reporting Information [Line Items]
Gross premiums written	$ 0	$ 0	$ 0	$ 0
Net premiums written	0	0	0	0
Net premiums earned	0	0	0	0
Third party fee income	0	0	0	0
Losses and loss adjustment expenses	0	0	0	0
Acquisition costs	0	0	0	0
Other underwriting expenses	0	0	0	0
Underwriting income (loss)	0	0	0	0
Net realized and unrealized gains (losses) on investments	48,228	47,343	454,851	101,881
Net investment income (loss)	17,330	8,069	43,667	17,719
Other income (loss), excluding third party fee income		85		85
Net foreign exchange gains (losses)	(5,973)	1,432	(9,883)	(3,953)
Corporate expenses	(14,060)	(18,678)	(41,825)	(31,833)
Amortization of intangible assets	(5,204)	(2,794)	(11,773)	(7,869)
Interest expense	(5,351)	(5,288)	(17,090)	(16,007)
Income tax expense (benefit)	(3,029)	(2,387)	(6,118)	(6,908)
Net income (loss) attributable to non-controlling interest	$ (17,215)	$ 9,065	$ 172,240	$ 15,076

Segment Reporting - Schedule _2

Segment Reporting - Schedule of Gross Premiums Written by Geographical Location of Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	$ 553,401	$ 474,123	$ 1,878,645	$ 1,517,247
Total International
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	325,525	307,140	957,981	832,049
Lloyd's of London
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	192,380	189,155	590,339	507,326
Ireland
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	99,650	96,272	283,776	271,002
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	33,495	21,713	83,866	53,721
Bermuda
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	$ 227,876	$ 166,983	$ 920,664	$ 685,198

Debt and Credit Facilities - Na

Debt and Credit Facilities - Narrative (Details) - USD ($)						3 Months Ended		9 Months Ended
	Oct. 28, 2024	Oct. 25, 2024	Aug. 12, 2024	Apr. 30, 2024	Jun. 23, 2022	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Aug. 08, 2023
Line of Credit Facility [Line Items]
Line of credit facility, outstanding						$ 746,786,000		$ 746,786,000
Interest expense						5,351,000	$ 5,288,000	17,090,000	$ 16,007,000
Unsecured Debt | Facility
Line of Credit Facility [Line Items]
Face amount					$ 150,000,000
Increase in interest rate in event of default					2%
Amortization of debt issuance costs						100,000	$ 100,000	100,000	$ 100,000
Line of Credit | Uncommitted Secured Letter Of Credit Facility | Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity										$ 200,000,000
Line of Credit | Unsecured Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity					$ 415,000,000
Line of credit facility, outstanding						$ 0		$ 0
Unused commitment fee percentage				0.175%	0.225%
Line of Credit | Unsecured Facility | Letter of Credit
Line of Credit Facility [Line Items]
Stated interest rate				1.375%	1.50%
Line of Credit | Unsecured Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity					$ 150,000,000
Basis spread on variable rate				1.625%	1.85%
Line of Credit | Bank of Montreal, Letter of Credit Facility | Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity			$ 50,000,000
Unused commitment fee percentage			0.15%
Commitment fee percentage			0.40%
Line of Credit | UBS Letter of Credit Facility | Letter of Credit | Subsequent Event
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 100,000,000
Commitment fee percentage		1.40%
Line of Credit | Unsecured Facility, Lloyd's | Letter of Credit | Subsequent Event
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 230,000,000
Commitment fee percentage	1.625%
Term of debt agreement	1 year

Debt and Credit Facilities - Sc

Debt and Credit Facilities - Schedule of Company Compliance (Details) - Facility - Unsecured Debt - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Line of Credit Facility [Line Items]
Outstanding loan balance	$ 150,000	$ 150,000
Fair value of debt	150,623	150,981
Unamortized issuance costs	$ 84	$ 170

Debt and Credit Facilities - _2

Debt and Credit Facilities - Schedule of Credit Facilities (Details) $ in Thousands	Sep. 30, 2024 USD ($)
Line of Credit Facility [Line Items]
Available letter of credit and revolving loan facilities - commitments	$ 995,000
Available letter of credit and revolving loan facilities - in use	746,786
TS Hamilton Fund
Line of Credit Facility [Line Items]
Security pledged under letter of credit and revolving loan facilities:	229,376
Fixed Income Portfolio
Line of Credit Facility [Line Items]
Security pledged under letter of credit and revolving loan facilities:	258,701
Cash
Line of Credit Facility [Line Items]
Security pledged under letter of credit and revolving loan facilities:	$ 5,271

Share Capital - Schedule of Sha

Share Capital - Schedule of Share Capital (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock authorized (in shares)	150,000,000	150,000,000	150,000,000	150,000,000	135,000,000	135,000,000
Common stock issued (in shares)	101,392,722	101,922,771	110,225,103	103,704,006	103,683,894	103,087,859
Common stock outstanding (in shares)	101,392,722	101,922,771	110,225,103	103,704,006	103,683,894	103,087,859
Common shares	$ 1,014		$ 1,101
Common Class A
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock authorized (in shares)	26,944,807	28,644,807	28,644,807	53,993,690	53,993,690	53,993,690
Common stock issued (in shares)	17,820,078	19,520,078	28,644,807	30,520,078	30,520,078	30,520,078
Common stock outstanding (in shares)	17,820,078	19,520,078	28,644,807	30,520,078	30,520,078	30,520,078
Common shares	$ 178		$ 286
Common Class B
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock authorized (in shares)	79,677,932	72,837,352	72,337,352	65,480,684	50,480,684	50,480,684
Common stock issued (in shares)	63,668,995	57,358,464	56,036,067	42,658,302	42,638,190	42,042,155
Common stock outstanding (in shares)	63,668,995	57,358,464	56,036,067	42,658,302	42,638,190	42,042,155
Common shares	$ 637		$ 560
Common Class C
Class of Stock [Line Items]
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock authorized (in shares)	19,903,649	25,044,229	25,544,229	30,525,626	30,525,626	30,525,626
Common stock issued (in shares)	19,903,649	25,044,229	25,544,229	30,525,626	30,525,626	30,525,626
Common stock outstanding (in shares)	19,903,649	25,044,229	25,544,229	30,525,626	30,525,626	30,525,626
Common shares	$ 199		$ 255

Share Capital - Schedule of Com

Share Capital - Schedule of Common Stock Authorized (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	150,000,000	135,000,000	150,000,000	135,000,000
Share class conversions (in shares)	0		0
Increase in authorized share capital (in shares)		15,000,000		15,000,000
Common shares - end of period (in shares)	150,000,000	150,000,000	150,000,000	150,000,000
Common stock authorized (in shares)	150,000,000	150,000,000	150,000,000	150,000,000
Common Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	28,644,807	53,993,690	28,644,807	53,993,690
Share class conversions (in shares)	(1,700,000)		(1,700,000)
Increase in authorized share capital (in shares)		0		0
Common shares - end of period (in shares)	26,944,807	53,993,690	26,944,807	53,993,690
Common stock authorized (in shares)	26,944,807	53,993,690	26,944,807	53,993,690
Common Class B
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	72,837,352	50,480,684	72,337,352	50,480,684
Share class conversions (in shares)	6,840,580		7,340,580
Increase in authorized share capital (in shares)		15,000,000		15,000,000
Common shares - end of period (in shares)	79,677,932	65,480,684	79,677,932	65,480,684
Common stock authorized (in shares)	79,677,932	65,480,684	79,677,932	65,480,684
Common Class C
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	25,044,229	30,525,626	25,544,229	30,525,626
Share class conversions (in shares)	(5,140,580)		(5,640,580)
Increase in authorized share capital (in shares)		0		0
Common shares - end of period (in shares)	19,903,649	30,525,626	19,903,649	30,525,626
Common stock authorized (in shares)	19,903,649	30,525,626	19,903,649	30,525,626
Unclassified Common Class
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	23,473,612	0	23,473,612	0
Share class conversions (in shares)	0		0
Increase in authorized share capital (in shares)		0		0
Common shares - end of period (in shares)	23,473,612	0	23,473,612	0
Common stock authorized (in shares)	23,473,612	0	23,473,612	0

Share Capital - Schedule of C_2

Share Capital - Schedule of Common Stock Issued and Outstanding (Details) - shares			3 Months Ended		9 Months Ended
	Sep. 13, 2024	May 08, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)			101,922,771	103,683,894	110,225,103	103,087,859
Common shares outstanding - beginning of period (in shares)			101,922,771	103,683,894	110,225,103	103,087,859
Vesting of awards (in shares)					761,261	735,013
Share class conversions (in shares)			0		0
Exercise of awards (in shares)					245,779
Director share awards granted (in shares)				20,112	20,383	44,892
Share repurchases (in shares)			(530,049)		(9,859,804)	(163,758)
Common shares issued - end of period (in shares)			101,392,722	103,704,006	101,392,722	103,704,006
Common shares outstanding - end of period (in shares)			101,392,722	103,704,006	101,392,722	103,704,006
Common Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)			19,520,078	30,520,078	28,644,807	30,520,078
Common shares outstanding - beginning of period (in shares)			19,520,078	30,520,078	28,644,807	30,520,078
Vesting of awards (in shares)					0	0
Share class conversions (in shares)			(1,700,000)		(1,700,000)
Exercise of awards (in shares)					0
Director share awards granted (in shares)				0	0	0
Share repurchases (in shares)		(9,100,000)	0		(9,124,729)	0
Common shares issued - end of period (in shares)			17,820,078	30,520,078	17,820,078	30,520,078
Common shares outstanding - end of period (in shares)			17,820,078	30,520,078	17,820,078	30,520,078
Common Class B
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)			57,358,464	42,638,190	56,036,067	42,042,155
Common shares outstanding - beginning of period (in shares)			57,358,464	42,638,190	56,036,067	42,042,155
Vesting of awards (in shares)					761,261	735,013
Share class conversions (in shares)			6,840,580		7,340,580
Exercise of awards (in shares)					245,779
Director share awards granted (in shares)				20,112	20,383	44,892
Share repurchases (in shares)			(530,049)		(735,075)	(163,758)
Common shares issued - end of period (in shares)			63,668,995	42,658,302	63,668,995	42,658,302
Common shares outstanding - end of period (in shares)			63,668,995	42,658,302	63,668,995	42,658,302
Common Class C
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)			25,044,229	30,525,626	25,544,229	30,525,626
Common shares outstanding - beginning of period (in shares)			25,044,229	30,525,626	25,544,229	30,525,626
Vesting of awards (in shares)					0	0
Share class conversions (in shares)	1,700,000		(5,140,580)		(5,640,580)
Exercise of awards (in shares)					0
Director share awards granted (in shares)				0	0	0
Share repurchases (in shares)			0		0	0
Common shares issued - end of period (in shares)			19,903,649	30,525,626	19,903,649	30,525,626
Common shares outstanding - end of period (in shares)			19,903,649	30,525,626	19,903,649	30,525,626

Share Capital - Narrative (Deta

Share Capital - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended	9 Months Ended
	Sep. 13, 2024	May 08, 2024	Sep. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Aug. 07, 2024
Class of Stock [Line Items]
Share repurchases (in shares)			530,049	9,859,804	163,758
Share repurchase authorization						$ 150
Remaining share repurchase authorization			$ 140	$ 140
Percent of combined voting power, Class A and Class B			9.50%	9.50%
Share class conversions (in shares)			0	0
Common Class A
Class of Stock [Line Items]
Share repurchases (in shares)		9,100,000	0	9,124,729	0
Shares acquired (in dollars per share)		$ 12
Share repurchases		$ 109.5
Share class conversions (in shares)			(1,700,000)	(1,700,000)
Common Class B
Class of Stock [Line Items]
Share repurchases (in shares)			530,049	735,075	163,758
Shares acquired (in dollars per share)			$ 18.87
Share repurchases			$ 10
Percent of combined voting power, Class A and Class B			14.92%	14.92%
Share class conversions (in shares)			6,840,580	7,340,580
Common Class C
Class of Stock [Line Items]
Share repurchases (in shares)			0	0	0
Share class conversions (in shares)	1,700,000		(5,140,580)	(5,640,580)

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Numerator:
Net income (loss) attributable to common shareholders	$ 78,250	$ 43,583	$ 366,509	$ 131,862
Denominator:
Weighted average common shares outstanding - basic (in shares)	101,934,000	103,704,000	106,240,000	103,711,000
Effect of dilutive securities (in shares)	4,425,000	1,720,000	3,986,000	1,260,000
Weighted average common shares outstanding - diluted (in shares)	106,359,000	105,424,000	110,226,000	104,971,000
Basic income (loss) per share attributable to common shareholders (in dollars per share)	$ 0.77	$ 0.42	$ 3.45	$ 1.27
Diluted income (loss) per share attributable to common shareholders (in dollars per share)	$ 0.74	$ 0.41	$ 3.33	$ 1.26
Anti-dilutive shares excluded from the calculation of diluted income (loss) per share (in shares)	0	0	0	0

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) - Subsequent Event - Hurricane Milton $ in Millions	Oct. 31, 2024 USD ($)
Minimum
Subsequent Event [Line Items]
Estimated loss from hurricane	$ 30
Maximum
Subsequent Event [Line Items]
Estimated loss from hurricane	$ 70