Hamilton Insurance (HG) 10-Q 9 May 24 2024 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2024	May 08, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 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		56,813,977
Entity Central Index Key	0001593275
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1

Unaudited Condensed Consolidate

Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets
Investments, at fair value	$ 2,229,198	$ 2,260,146
Investments in Two Sigma Funds, at fair value (cost 2024: $753,967; 2023: $770,191)	953,659	851,470
Total investments	3,182,857	3,111,616
Cash and cash equivalents	1,085,038	794,509
Restricted cash and cash equivalents	95,565	106,351
Premiums receivable	856,111	658,363
Paid losses recoverable	169,469	145,202
Deferred acquisition costs	190,883	156,895
Unpaid losses and loss adjustment expenses recoverable	1,167,504	1,161,077
Receivables for investments sold	17,777	42,419
Prepaid reinsurance	285,984	194,306
Intangible assets	92,651	90,996
Other assets	205,186	209,621
Total assets	7,349,025	6,671,355
Liabilities, non-controlling interest, and shareholders’ equity
Reserve for losses and loss adjustment expenses	3,148,782	3,030,037
Unearned premiums	1,132,477	911,222
Reinsurance balances payable	367,123	272,310
Payables for investments purchased	55,071	66,606
Term loan, net of issuance costs	149,859	149,830
Accounts payable and accrued expenses	155,684	186,887
Payables to related parties	75,797	6,480
Total liabilities	5,084,793	4,623,372
Non-controlling interest – TS Hamilton Fund	54,727	133
Shareholders’ equity
Common shares:	1,109	1,101
Additional paid-in capital	1,255,055	1,249,817
Accumulated other comprehensive loss	(4,441)	(4,441)
Retained earnings	957,782	801,373
Total shareholders’ equity	2,209,505	2,047,850
Total liabilities, non-controlling interest, and shareholders’ equity	7,349,025	6,671,355
Total fixed maturities
Assets
Investments, at fair value	1,877,130	1,831,268
Short-term investments
Assets
Investments, at fair value	352,068	428,878
Common Class A
Shareholders’ equity
Common shares:	286	286
Common Class B
Shareholders’ equity
Common shares:	568	560
Common Class C
Shareholders’ equity
Common shares:	$ 255	$ 255

Unaudited Condensed Consolida_2

Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Investments, amortized cost	$ 2,277,364	$ 2,294,936
Investments in two sigma funds, cost	$ 753,967	$ 770,191
Common stock authorized (in shares)	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)	111,003,013	110,225,103	103,730,442	103,087,859
Common stock outstanding (in shares)	111,003,013	110,225,103	103,730,442	103,087,859
Total fixed maturities
Investments, amortized cost	$ 1,926,329	$ 1,867,499
Short-term investments
Investments, amortized cost	$ 351,035	$ 427,437
Common Class A
Common stock authorized (in shares)	28,644,807	28,644,807	53,993,690	53,993,690
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued (in shares)	28,644,807	28,644,807	30,520,078	30,520,078
Common stock outstanding (in shares)	28,644,807	28,644,807	30,520,078	30,520,078
Common Class B
Common stock authorized (in shares)	72,337,352	72,337,352	50,480,684	50,480,684
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued (in shares)	56,813,977	56,036,067	42,684,738	42,042,155
Common stock outstanding (in shares)	56,813,977	56,036,067	42,684,738	42,042,155
Common Class C
Common stock authorized (in shares)	25,544,229	25,544,229	30,525,626	30,525,626
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued (in shares)	25,544,229	25,544,229	30,525,626	30,525,626
Common stock outstanding (in shares)	25,544,229	25,544,229	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
	Mar. 31, 2024	Mar. 31, 2023
Revenues
Gross premiums written	$ 721,941	$ 538,164
Reinsurance premiums ceded	(207,061)	(189,666)
Net premiums written	514,880	348,498
Net change in unearned premiums	(129,577)	(64,596)
Net premiums earned	385,303	283,902
Net realized and unrealized gains (losses) on investments	255,371	35,133
Net investment income (loss)	12,618	2,359
Total net realized and unrealized gains (losses) on investments and net investment income (loss)	267,989	37,492
Other income (loss)	7,478	3,033
Net foreign exchange gains (losses)	(2,125)	(2,046)
Total revenues	658,645	322,381
Expenses
Losses and loss adjustment expenses	232,352	148,561
Acquisition costs	84,554	65,140
General and administrative expenses	54,855	45,806
Amortization of intangible assets	3,252	2,770
Interest expense	5,708	5,529
Total expenses	380,721	267,806
Income (loss) before income tax	277,924	54,575
Income tax expense (benefit)	592	1,573
Net income (loss)	277,332	53,002
Net income (loss) attributable to non-controlling interest	120,158	1,510
Net income (loss) and other comprehensive income (loss) attributable to common shareholders	$ 157,174	$ 51,492
Per share data
Basic income (loss) per share attributable to common shareholders (in dollars per share)	$ 1.42	$ 0.50
Diluted income (loss) per share attributable to common shareholders (in dollars per share)	$ 1.38	$ 0.49

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		$ 1,030	$ 1,120,242	$ (4,441)	$ 547,352
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares		7	(7)
Repurchases of common shares		0	(1,274)		(334)
Share compensation expense			2,373
Net income (loss)	$ 53,002				53,002
Net income attributable to non-controlling interest	(1,510)				(1,510)
Balance, end of period at Mar. 31, 2023	1,716,440	1,037	1,121,334	(4,441)	598,510
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		10	387
Repurchases of common shares		(2)	(2,442)		(765)
Share compensation expense			7,293
Net income (loss)	277,332				277,332
Net income attributable to non-controlling interest	(120,158)				(120,158)
Balance, end of period at Mar. 31, 2024	$ 2,209,505	$ 1,109	$ 1,255,055	$ (4,441)	$ 957,782

Unaudited Condensed Consolida_5

Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net income (loss)	$ 277,332	$ 53,002
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	3,625	3,085
Share compensation expense	7,293	2,373
Net realized (gains) losses on investments	(149,445)	37,651
Change in net unrealized (gains) losses on investments	(105,926)	(72,784)
Other items	2,367	(650)
Change in:
Premiums receivable	(197,748)	(137,052)
Paid losses recoverable	(24,267)	18,564
Deferred acquisition costs	(33,988)	(20,947)
Prepaid reinsurance	(91,678)	(87,414)
Unpaid losses and loss adjustment expenses recoverable	(6,427)	(14,420)
Other assets	4,135	(6,536)
Reserve for losses and loss adjustment expenses	118,745	35,237
Unearned premiums	221,255	153,145
Reinsurance balances payable	94,813	68,966
Accounts payable and accrued expenses and other	38,114	(20,134)
Net cash provided by (used in) operating activities	158,200	12,086
Investing activities
Proceeds from redemptions from Two Sigma Funds	837,829	733,302
Contributions to Two Sigma Funds	(678,366)	(636,737)
Purchases of fixed maturity investments	(447,062)	(257,903)
Proceeds from sales, redemptions and maturity of fixed maturity investments	387,133	158,237
Purchases of short-term investments	(350,125)	(387,165)
Proceeds from sales of short-term investments	436,591	291,323
Change in receivables for investments sold	24,642	(33,247)
Change in payables for investments purchased	(11,535)	5,794
Other	(4,980)	(5,733)
Net cash provided by (used in) investing activities	194,127	(132,129)
Financing activities
Issuance of common shares	10	7
Repurchases of common shares	(3,209)	(1,608)
Contribution of additional paid-in capital	387	(7)
Withdrawal of non-controlling interest	(65,564)	(1,509)
Net cash provided by (used in) financing activities	(68,376)	(3,117)
Effect of exchange rate changes on cash and cash equivalents and restricted cash and cash equivalents	(4,208)	772
Net increase (decrease) in cash and cash equivalents and restricted cash and cash equivalents	279,743	(122,388)
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	$ 1,180,603	$ 1,084,815

Organization

Organization	3 Months Ended
	Mar. 31, 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. The Company's net proceeds from the IPO were $80.6 million, after deducting underwriting discounts and specific incremental expenses directly attributable to the IPO. 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 capital and profits allocated to Hamilton Re US are subject to applicable 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 is 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 6, Reinsurance , for further details.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 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	3 Months Ended
	Mar. 31, 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 at March 31, 2024 and December 31, 2023 are as follows: 2024 ($ in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturities: U.S. government treasuries $ 636,151 $ 782 $ (15,682) $ 621,251 U.S. states, territories and municipalities 4,481 — (253) 4,228 Non-U.S. sovereign governments and supranationals 62,211 977 (1,199) 61,989 Corporate 918,909 4,290 (21,816) 901,383 Residential mortgage-backed securities - Agency 232,441 340 (15,000) 217,781 Residential mortgage-backed securities - Non-agency 6,124 9 (711) 5,422 Commercial mortgage-backed securities - Non-agency 33,321 85 (936) 32,470 Other asset-backed securities 32,691 56 (141) 32,606 Total fixed maturities 1,926,329 6,539 (55,738) 1,877,130 Short-term investments 351,035 1,034 (1) 352,068 Total $ 2,277,364 $ 7,573 $ (55,739) $ 2,229,198 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 at March 31, 2024. 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. 2024 ($ in thousands) Amortized Cost Fair Value Due less than one year $ 137,552 $ 134,603 Due after one through five years 1,264,516 1,236,870 Due after five through ten years 216,276 214,483 Due after ten years 3,408 2,895 Mortgage-backed 271,886 255,673 Asset-backed 32,691 32,606 Total $ 1,926,329 $ 1,877,130 Investments in Two Sigma Funds The Company’s investments in Two Sigma Funds at March 31, 2024 and December 31, 2023 are as follows: 2024 2023 ($ in thousands) Cost Net Unrealized Gains (Losses) Fair Value Cost Net Unrealized Gains (Losses) Fair Value Two Sigma Futures Portfolio, LLC (FTV) $ 337,916 $ 59,294 $ 397,210 $ 433,911 $ (38,105) $ 395,806 Two Sigma Spectrum Portfolio, LLC (STV) 246,490 91,849 338,339 193,299 88,228 281,527 Two Sigma Equity Spectrum Portfolio, LLC (ESTV) 169,561 48,549 218,110 142,981 31,156 174,137 Total $ 753,967 $ 199,692 $ 953,659 $ 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 March 31, 2024, the Company owns a 17.7%, 18.7% and 10.2% 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 at March 31, 2024: 2024 ($ in thousands) Principal / Shares (1) Fair Value (1) % of Members' Equity U.S. Treasury Securities, 0.0000%- 4.5000%, due 4/2/2024 - 2/15/2054 996,048 $ 987,600 51.5 % State Street Treasury Obligations Money Market Fund 172,946 $ 172,946 9.0 % U.S. Treasury Securities, 4.2500%- 4.5000%, due 3/15/2027 - 2/15/2054 (41,401) $ (41,033) (2.1) % (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 March 31, 2024 and 2023 was $11.4 million and $11.9 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 March 31, 2024 and 2023 was $120.1 million and $1.5 million, respectively. Hamilton Re has a commitment with TS Hamilton Fund to maintain an amount up to the lesser of (i) $1.8 billion or (ii) 60% of Hamilton Insurance Group’s net tangible assets in TS Hamilton Fund, such lesser amount, the "Minimum Commitment Amount", for a three-year period (the "Initial Term") and for rolling three-year periods thereafter (each such three-year period the "Commitment Period"), subject to certain circumstances and the liquidity options described below, with the Commitment Period ending on June 30, 2026. The Commitment Period consists of a 3-year rolling term that automatically renews on an annual basis unless Hamilton Re or the Managing Member provide advance notice of non-renewal. The TS Hamilton Fund generally has two liquidity options, subject to Hamilton Re’s minimum investment commitment, which are as follows: • Monthly liquidity - Subject to certain conditions, Hamilton Re may request a whole or partial withdrawal of its capital account, no later than fifteen days prior to the end of a calendar month, effective as of the last day of such calendar month. • Daily liquidity - Subject to certain limited circumstances, including the need to meet obligations pursuant to Hamilton Re’s underwriting operations, Hamilton Re may request a withdrawal of all or a portion of its capital account upon at least one At its discretion, the Managing Member may permit or require Hamilton Re to withdraw all or any portion of its respective capital account at other times, or waive or reduce certain notice periods, or allow a notice to be revoked. The Managing Member may withdraw all or any portion of its capital account at any time. Total Net Realized and Unrealized Gains (Losses) on Investments and Net Investment Income (Loss) The components of total net realized and unrealized gains (losses) on investments and net investment income (loss) for the three months ended March 31, 2024 and 2023 are as follows: ($ in thousands) 2024 2023 Net realized and unrealized gains (losses) on investments: Net realized gains (losses) on investments $ 149,445 $ (37,651) Change in net unrealized gains (losses) on investments 105,926 72,784 Net realized and unrealized gains (losses) on investments 255,371 35,133 Net investment income (loss): Fixed maturities 16,950 8,155 Short-term investments (1) 153 TS Hamilton Fund 3,015 3,888 Cash and cash equivalents 4,115 2,309 Other 752 423 Interest and other 24,831 14,928 Management fees (11,950) (12,333) Other expenses (263) (236) Net investment income (loss) 12,618 2,359 Total net realized and unrealized gains (losses) on investments and net investment income (loss) $ 267,989 $ 37,492 Net Realized Gains (Losses) on Investments The components of net realized gains (losses) on investments for the three months ended March 31, 2024 and 2023 are as follows: ($ in thousands) 2024 2023 Fixed maturities and short-term investments $ (2,942) $ (5,681) TS Hamilton Fund 152,387 (31,970) Net realized gains (losses) on investments $ 149,445 $ (37,651) Net Unrealized Gains (Losses) on Investments The components of net unrealized gains (losses) on investments for the three months ended March 31, 2024 and 2023 are as follows: ($ in thousands) 2024 2023 Fixed maturities and short-term investments $ (12,991) $ 22,557 TS Hamilton Fund 118,917 50,227 Net unrealized gains (losses) on investments $ 105,926 $ 72,784 Pledged Assets At March 31, 2024 and December 31, 2023, pledged investments at fair value were comprised of $237.0 million and $232.2 million, respectively, securing a portion of the capital requirements for business written at Lloyd's, $54.1 million and $54.1 million, respectively, held in trust accounts for the benefit of U.S. state regulatory authorities and $36.7 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 9, Debt and Credit Facilities . At March 31, 2024 and December 31, 2023, restricted cash and cash equivalents balances were comprised of $92.3 million and $97.4 million, respectively, securing other underwriting obligations, $1.6 million and $7.2 million, respectively, securing a portion of the capital requirements for business written at Lloyd's, $1.4 million and $1.5 million, respectively, in trust accounts for the benefit of regulatory authorities, and $0.3 million and $0.3 million, respectively, of escrow funds. Total cash and cash equivalents and restricted cash and cash equivalents of $1.2 billion presented in the statement of cash flows was comprised of cash and cash equivalents of $1.1 billion and restricted cash and cash equivalents of $95.6 million on the balance sheet at March 31, 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	3 Months Ended
	Mar. 31, 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 at March 31, 2024 and December 31, 2023: 2024 ($ in thousands) Level 1 Level 2 Level 3 Total Fixed maturities: U.S. government treasuries $ — $ 621,251 $ — $ 621,251 U.S. states, territories and municipalities — 4,228 — 4,228 Non-U.S. sovereign governments and supranationals — 61,989 — 61,989 Corporate — 901,383 — 901,383 Residential mortgage-backed securities - Agency — 217,781 — 217,781 Residential mortgage-backed securities - Non-agency — 5,422 — 5,422 Commercial mortgage-backed securities - Non-agency — 32,470 — 32,470 Other asset-backed securities — 32,606 — 32,606 Total fixed maturities — 1,877,130 — 1,877,130 Short-term investments — 352,068 — 352,068 Total $ — $ 2,229,198 $ — $ 2,229,198 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	3 Months Ended
	Mar. 31, 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 for the three months ended March 31, 2024 and 2023 was as follows: ($ in thousands) 2024 2023 Balance - beginning of period $ 133 $ 119 Withdrawals (65,564) (1,509) Equity in earnings 21 1 Incentive allocation 120,137 1,509 Balance - end of period $ 54,727 $ 120 The following table presents the total assets and total liabilities of TS Hamilton Fund at March 31, 2024 and December 31, 2023. 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) 2024 2023 Assets Cash and cash equivalents $ 706,969 $ 479,255 Short-term investments 348,155 428,878 Investments in Two Sigma Funds, at fair value 953,659 851,470 Receivables for investments sold 13,868 41,087 Interest and dividends receivable 1,024 966 Total assets 2,023,675 1,801,656 Liabilities Accounts payable and accrued expenses 178 191 Withdrawal payable 75,797 6,480 Payable for investments purchased 28,132 62,440 Total liabilities 104,107 69,111 Total net assets managed by TS Hamilton Fund $ 1,919,568 $ 1,732,545

Reinsurance

Reinsurance	3 Months Ended
	Mar. 31, 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 March 31, 2024, the Company’s premiums receivable balance, net of credit provisions of $2.2 million, was $856.1 million. At December 31, 2023, the Company’s premiums receivable balance, net of credit provisions of $3.0 million, was $658.4 million. The following table provides a roll forward of the provision for current expected credit losses of the Company's premiums receivable for the three months ended March 31, 2024 and 2023: ($ in thousands) 2024 2023 Beginning balance $ 3,000 $ 2,856 Increase (decrease) in allowance (847) 280 Ending balance $ 2,153 $ 3,136 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 March 31, 2024, the Company’s paid and unpaid reinsurance recoverable balances net of credit provisions were $169.5 million and $1.2 billion, respectively, with a total corresponding provision for current expected credit losses of $0.7 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 $0.7 million. The following table provides a roll forward of the provision for current expected credit losses of the Company's reinsurance recoverable for the three months ended March 31, 2024 and 2023: ($ in thousands) 2024 2023 Beginning balance $ 687 $ 777 Provision for (release of) allowance 22 15 Ending balance $ 709 $ 792 At March 31, 2024 and December 31, 2023, 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 2024 2023 Collateralized 25.2 % 28.5 % A- or better 74.3 % 71.0 % Below A- 0.5 % 0.5 % Total 100.0 % 100.0 % At March 31, 2024 and December 31, 2023, the three largest balances by reinsurer accounted for 25%, 22% and 12%, 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 March 31, 2024 and December 31, 2023, the balance of reinsurance recoverable on unpaid losses due under this LPT was $47.3 million and $49.8 million, respectively. Amortization of the deferred gain was income of $0.9 million and $0.2 million during the three months ended March 31, 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 $14.6 million during the three months ended March 31, 2024.

Reserve for Losses and Loss Adj

Reserve for Losses and Loss Adjustment Expenses	3 Months Ended
	Mar. 31, 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 three months ended March 31, 2024 and 2023: ($ 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 220,295 144,556 Prior years 12,057 4,005 Total incurred 232,352 148,561 Net losses and loss adjustment expenses paid in respect of losses occurring in: Current year 3,336 7,936 Prior years 113,015 129,702 Total paid 116,351 137,638 Foreign currency revaluation and other (3,683) 9,894 Net unpaid losses and loss adjustment expenses, end of period 1,981,278 1,699,229 Reinsurance recoverable on unpaid losses 1,167,504 1,192,283 Gross unpaid losses and loss adjustment expenses, end of period $ 3,148,782 $ 2,891,512 Net unfavorable prior year development of $12.1 million for the three months ended March 31, 2024 was primarily driven by attritional losses. See below for further details: • Net unfavorable development of $11.4 million on specialty contracts, primarily driven by two specific large claims; and • Net unfavorable development of $4.0 million on casualty contracts, due to higher than expected claims development across certain classes; partially offset by • Net favorable development of $2.5 million on property contracts, driven by overall lower than expected claims development across various classes; and • In addition, casualty business protected by the LPT discussed in Note 6, Reinsurance , benefited from $0.9 million in amortization of the associated deferred gain, partially offset by unfavorable development in the underlying reserves of $0.1 million, for a total net positive earnings impact of $0.8 million. Net unfavorable prior year development of $4.0 million for the three months ended March 31, 2023 was comprised of $2.2 million and $1.8 million of unfavorable prior year development on catastrophe and attritional losses, respectively. See below for further details: • Net unfavorable development of $12.1 million on property contracts, primarily driven by development of losses that occurred in 2022, including Winterstom Elliot; offset by • Net favorable development of $5.4 million on specialty contracts, driven by lower than expected claims development across various classes; • Net favorable development of $1.0 million on casualty lines of business, primarily related to lower than expected loss experience; and • In addition, casualty business protected by the LPT discussed in Note 6, Reinsurance , recorded favorable gross development and amortization of the associated deferred gain, resulting in a net positive earnings impact of $1.8 million. Reinsurance recoverable on unpaid losses related to the LPT discussed in Note 6, Reinsurance , was recognized for each of the three months ended March 31, 2024 and 2023 in the reconciliation of beginning and ending gross and net loss and LAE reserves presented above. The Company amortized acquisition costs of $84.6 million and $65.1 million for the three months ended March 31, 2024 and 2023, respectively. Baltimore Bridge The estimate of net reserves for losses and loss adjustment expenses related to the Francis Scott Key Baltimore Bridge collapse on March 26, 2024 is subject to significant uncertainty. As at March 31, 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 also remain subject to significant uncertainty. As at March 31, 2024 and December 31, 2023, our recorded reserves totaled $64.4 million and $64.9 million, respectively. Covid-19 Our Covid-19 losses also remain subject to significant uncertainty. As at March 31, 2024 and December 31, 2023, our recorded reserves relating to Covid-19 totaled $15.8 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 March 31, 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	3 Months Ended
	Mar. 31, 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 March 31, 2024 International Bermuda Corporate Total Gross premiums written $ 320,841 $ 401,100 $ — $ 721,941 Net premiums written $ 185,033 $ 329,847 $ — $ 514,880 Net premiums earned $ 196,814 $ 188,489 $ — $ 385,303 Third party fee income 3,586 3,892 — 7,478 Losses and loss adjustment expenses 116,162 116,190 — 232,352 Acquisition costs 47,720 36,834 — 84,554 Other underwriting expenses 31,203 12,150 — 43,353 Underwriting income (loss) $ 5,315 $ 27,207 $ — $ 32,522 Net realized and unrealized gains (losses) on investments 255,371 255,371 Net investment income (loss) 12,618 12,618 Net foreign exchange gains (losses) (2,125) (2,125) Corporate expenses (11,502) (11,502) Amortization of intangible assets (3,252) (3,252) Interest expense (5,708) (5,708) Income (loss) before income tax 277,924 Income tax (expense) benefit (592) (592) Net income (loss) 277,332 Net income (loss) attributable to non-controlling interest 120,158 120,158 Net income (loss) attributable to common shareholders $ 157,174 Key Ratios Attritional loss ratio - current year 56.0 % 58.4 % 57.2 % Attritional loss ratio - prior year development 2.9 % 3.2 % 3.1 % Catastrophe loss ratio - current year 0.0 % 0.0 % 0.0 % Catastrophe loss ratio - prior year development 0.1 % 0.0 % 0.0 % Loss and loss adjustment expense ratio 59.0 % 61.6 % 60.3 % Acquisition cost ratio 24.2 % 19.5 % 21.9 % Other underwriting expense ratio 14.0 % 4.4 % 9.3 % Combined ratio 97.2 % 85.5 % 91.5 % ($ in thousands) Three Months Ended March 31, 2023 International Bermuda Corporate Total Gross premiums written $ 247,114 $ 291,050 $ — $ 538,164 Net premiums written $ 122,019 $ 226,479 $ — $ 348,498 Net premiums earned $ 149,515 $ 134,387 $ — $ 283,902 Third party fee income 2,902 102 — 3,004 Losses and loss adjustment expenses 70,393 78,168 — 148,561 Acquisition costs 37,193 27,947 — 65,140 Other underwriting expenses 28,461 10,681 — 39,142 Underwriting income (loss) $ 16,370 $ 17,693 $ — $ 34,063 Net realized and unrealized gains (losses) on investments 35,133 35,133 Net investment income (loss) 2,359 2,359 Other income (loss), excluding third party fee income 29 29 Net foreign exchange gains (losses) (2,046) (2,046) Corporate expenses (6,664) (6,664) Amortization of intangible assets (2,770) (2,770) Interest expense (5,529) (5,529) Income (loss) before income tax 54,575 Income tax (expense) benefit (1,573) (1,573) Net income (loss) 53,002 Net income (loss) attributable to non-controlling interest 1,510 1,510 Net income (loss) attributable to common shareholders $ 51,492 Key Ratios Attritional loss ratio - current year 49.9 % 48.1 % 49.1 % Attritional loss ratio - prior year development (4.2) % 6.1 % 0.6 % Catastrophe loss ratio - current year 0.0 % 3.9 % 1.8 % Catastrophe loss ratio - prior year development 1.4 % 0.1 % 0.8 % Loss and loss adjustment expense ratio 47.1 % 58.2 % 52.3 % Acquisition cost ratio 24.9 % 20.8 % 22.9 % Other underwriting expense ratio 17.1 % 7.9 % 12.7 % Combined ratio 89.1 % 86.9 % 87.9 % The following table presents gross premiums written by the geographical location of the Company's subsidiaries for the three months ended March 31, 2024 and 2023: ($ in thousands) 2024 2023 International Lloyd's of London $ 198,581 $ 148,709 Ireland 99,073 83,764 U.S. 23,187 14,641 Total International 320,841 247,114 Bermuda 401,100 291,050 Total $ 721,941 $ 538,164

Debt and Credit Facilities

Debt and Credit Facilities	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Debt and Credit Facilities	Debt and Credit Facilities Debt On June 23, 2022, Hamilton Group renewed its unsecured $150 million term loan credit arrangement, as amended from time to time (the "Facility"), with various lenders as arranged by Wells Fargo Securities, LLC. All or a portion of the loan issued under the renegotiated Facility bears interest at either (a) the Base Rate plus the Applicable Margin or (b) the Adjusted Term Secured Overnight Financing Rate ("SOFR") plus the Applicable Margin, at Hamilton Group's discretion. In the event of default, an additional 2% interest in excess of (a) or (b) will be levied, not to exceed the highest rate permissible under applicable law, and certain types of loans may not be available for borrowing by Hamilton Group under the Facility. The Facility matures on June 23, 2025, unless accelerated pursuant to the terms of the Facility, and it contains usual and customary representations, warranties, conditions and covenants for bank loan facilities of this type. The Facility also contains certain financial covenants which cap the ratio of consolidated debt to capital and require that Hamilton Group maintain a certain minimum consolidated net worth. The net worth requirement is recalculated effective as of the end of each fiscal quarter. As of March 31, 2024, the Company was in compliance with all covenants . As at ($ in thousands) March 31, December 31, Outstanding loan balance $ 150,000 $ 150,000 Loan fair value 151,000 151,000 Unamortized loan issuance costs $ 141 $ 170 Debt issuance costs are amortized over the period during which the Facility is outstanding, as an offset to investment income. The Company amortized debt issuance costs of less than $0.1 million in each of the three months ended March 31, 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 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 March 31, 2024, there were no loan amounts outstanding under this facility. Letters of credit issued under the facility bear interest at a rate of 150 basis points, while revolving loans if issued are subject to a fee of SOFR plus a margin of 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 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 11, 2023, 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, 2024. 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. On October 26, 2023, 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 26, 2024. The facility bears a fee of 140 basis points on the total available capacity. In addition, on October 27, 2023, 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 was increased to $230 million for an additional one year term that expires on October 27, 2024. The facility bears a fee of 162.5 basis points on the borrowed amount. The Company’s obligations under its credit facilities require Hamilton Group, Hamilton Re and the other parties thereto to comply with various financial and reporting covenants. All applicable entities were in compliance with all such covenants at March 31, 2024. Certain of the Company's credit facilities are secured by pledged interests in the TS Hamilton Fund, the Company's fixed income security portfolio, or cash. The Company’s credit facilities at March 31, 2024, and associated securities pledged, were as follows: ($ in thousands) 2024 Available letter of credit and revolving loan facilities - commitments $ 995,000 Available letter of credit and revolving loan facilities - in use 745,958 Security pledged under letter of credit and revolving loan facilities: Pledged interests in TS Hamilton Fund $ 237,461 Pledged interests in fixed income portfolio 251,588 Cash 2,339 The Company has recognized interest expense related to the above debt and credit facilities of $5.7 million and $5.5 million for the three months ended March 31, 2024 and 2023, respectively.

Share Capital

Share Capital	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Share Capital	Share Capital Authorized and Issued Hamilton Group’s share capital at March 31, 2024 and December 31, 2023, is comprised as follows: ($ in thousands) Authorized: Common shares of $0.01 par value each (2024 and 2023: 150,000,000) Issued, outstanding and fully paid: 2024 2023 Class A common shares (2024 and 2023: 28,644,807) $ 286 $ 286 Class B common shares (2024: 56,813,977 and 2023: 56,036,067) 568 560 Class C common shares (2024 and 2023: 25,544,229) 255 255 Total $ 1,109 $ 1,101 The following is a summary of the activity related to common shares authorized for the three months ended March 31, 2024 and 2023: 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 Balance - March 31, 2024 28,644,807 72,337,352 25,544,229 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 Balance - March 31, 2023 53,993,690 50,480,684 30,525,626 — 135,000,000 The following is a summary of the activity related to common shares issued and outstanding for the three months ended March 31, 2024 and 2023: Class A Class B Class C Total Balance - December 31, 2023 28,644,807 56,036,067 25,544,229 110,225,103 Vesting of awards — 761,261 — 761,261 Exercise of warrants — 201,292 — 201,292 Director share awards granted — 20,383 — 20,383 Share repurchases — (205,026) — (205,026) Balance - March 31, 2024 28,644,807 56,813,977 25,544,229 111,003,013 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 — 24,780 — 24,780 Share repurchases — (117,210) — (117,210) Balance - March 31, 2023 30,520,078 42,684,738 30,525,626 103,730,442 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.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 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 for the three months ended March 31, 2024 and 2023, respectively: ($ in thousands, except per share information) 2024 2023 Numerator: Net income (loss) attributable to common shareholders $ 157,174 $ 51,492 Denominator: Weighted average common shares outstanding - basic 110,921 103,732 Effect of dilutive securities 3,325 893 Weighted average common shares outstanding - diluted 114,246 104,625 Basic income (loss) per share attributable to common shareholders $ 1.42 $ 0.50 Diluted income (loss) per share attributable to common shareholders $ 1.38 $ 0.49

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On May 8, 2024, the Company entered into an agreement to repurchase 9,124,729 Class A common shares at $12.00 per share. The total purchase price for those shares is $109.5 million. The Company expects to close the repurchase transaction on May 10, 2024 subject to customary closing conditions. The common shares purchased by the Company will be cancelled and the Company will have 101,878,284 shares issued and outstanding following the repurchase transaction.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 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)	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Fixed Maturity and Short-Term Investments	The Company’s fixed maturity and short-term investments at March 31, 2024 and December 31, 2023 are as follows: 2024 ($ in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Fixed maturities: U.S. government treasuries $ 636,151 $ 782 $ (15,682) $ 621,251 U.S. states, territories and municipalities 4,481 — (253) 4,228 Non-U.S. sovereign governments and supranationals 62,211 977 (1,199) 61,989 Corporate 918,909 4,290 (21,816) 901,383 Residential mortgage-backed securities - Agency 232,441 340 (15,000) 217,781 Residential mortgage-backed securities - Non-agency 6,124 9 (711) 5,422 Commercial mortgage-backed securities - Non-agency 33,321 85 (936) 32,470 Other asset-backed securities 32,691 56 (141) 32,606 Total fixed maturities 1,926,329 6,539 (55,738) 1,877,130 Short-term investments 351,035 1,034 (1) 352,068 Total $ 2,277,364 $ 7,573 $ (55,739) $ 2,229,198 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 at March 31, 2024. 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. 2024 ($ in thousands) Amortized Cost Fair Value Due less than one year $ 137,552 $ 134,603 Due after one through five years 1,264,516 1,236,870 Due after five through ten years 216,276 214,483 Due after ten years 3,408 2,895 Mortgage-backed 271,886 255,673 Asset-backed 32,691 32,606 Total $ 1,926,329 $ 1,877,130
Schedule of Investments in Two Sigma Funds	The Company’s investments in Two Sigma Funds at March 31, 2024 and December 31, 2023 are as follows: 2024 2023 ($ in thousands) Cost Net Unrealized Gains (Losses) Fair Value Cost Net Unrealized Gains (Losses) Fair Value Two Sigma Futures Portfolio, LLC (FTV) $ 337,916 $ 59,294 $ 397,210 $ 433,911 $ (38,105) $ 395,806 Two Sigma Spectrum Portfolio, LLC (STV) 246,490 91,849 338,339 193,299 88,228 281,527 Two Sigma Equity Spectrum Portfolio, LLC (ESTV) 169,561 48,549 218,110 142,981 31,156 174,137 Total $ 753,967 $ 199,692 $ 953,659 $ 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 at March 31, 2024: 2024 ($ in thousands) Principal / Shares (1) Fair Value (1) % of Members' Equity U.S. Treasury Securities, 0.0000%- 4.5000%, due 4/2/2024 - 2/15/2054 996,048 $ 987,600 51.5 % State Street Treasury Obligations Money Market Fund 172,946 $ 172,946 9.0 % U.S. Treasury Securities, 4.2500%- 4.5000%, due 3/15/2027 - 2/15/2054 (41,401) $ (41,033) (2.1) % (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) for the three months ended March 31, 2024 and 2023 are as follows: ($ in thousands) 2024 2023 Net realized and unrealized gains (losses) on investments: Net realized gains (losses) on investments $ 149,445 $ (37,651) Change in net unrealized gains (losses) on investments 105,926 72,784 Net realized and unrealized gains (losses) on investments 255,371 35,133 Net investment income (loss): Fixed maturities 16,950 8,155 Short-term investments (1) 153 TS Hamilton Fund 3,015 3,888 Cash and cash equivalents 4,115 2,309 Other 752 423 Interest and other 24,831 14,928 Management fees (11,950) (12,333) Other expenses (263) (236) Net investment income (loss) 12,618 2,359 Total net realized and unrealized gains (losses) on investments and net investment income (loss) $ 267,989 $ 37,492
Schedule of Realized Gain (Loss) on Investments	The components of net realized gains (losses) on investments for the three months ended March 31, 2024 and 2023 are as follows: ($ in thousands) 2024 2023 Fixed maturities and short-term investments $ (2,942) $ (5,681) TS Hamilton Fund 152,387 (31,970) Net realized gains (losses) on investments $ 149,445 $ (37,651)
Schedule of Unrealized Gain (Loss) on Investments	The components of net unrealized gains (losses) on investments for the three months ended March 31, 2024 and 2023 are as follows: ($ in thousands) 2024 2023 Fixed maturities and short-term investments $ (12,991) $ 22,557 TS Hamilton Fund 118,917 50,227 Net unrealized gains (losses) on investments $ 105,926 $ 72,784

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 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 at March 31, 2024 and December 31, 2023: 2024 ($ in thousands) Level 1 Level 2 Level 3 Total Fixed maturities: U.S. government treasuries $ — $ 621,251 $ — $ 621,251 U.S. states, territories and municipalities — 4,228 — 4,228 Non-U.S. sovereign governments and supranationals — 61,989 — 61,989 Corporate — 901,383 — 901,383 Residential mortgage-backed securities - Agency — 217,781 — 217,781 Residential mortgage-backed securities - Non-agency — 5,422 — 5,422 Commercial mortgage-backed securities - Non-agency — 32,470 — 32,470 Other asset-backed securities — 32,606 — 32,606 Total fixed maturities — 1,877,130 — 1,877,130 Short-term investments — 352,068 — 352,068 Total $ — $ 2,229,198 $ — $ 2,229,198 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)	3 Months Ended
	Mar. 31, 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 for the three months ended March 31, 2024 and 2023 was as follows: ($ in thousands) 2024 2023 Balance - beginning of period $ 133 $ 119 Withdrawals (65,564) (1,509) Equity in earnings 21 1 Incentive allocation 120,137 1,509 Balance - end of period $ 54,727 $ 120 The following table presents the total assets and total liabilities of TS Hamilton Fund at March 31, 2024 and December 31, 2023. 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) 2024 2023 Assets Cash and cash equivalents $ 706,969 $ 479,255 Short-term investments 348,155 428,878 Investments in Two Sigma Funds, at fair value 953,659 851,470 Receivables for investments sold 13,868 41,087 Interest and dividends receivable 1,024 966 Total assets 2,023,675 1,801,656 Liabilities Accounts payable and accrued expenses 178 191 Withdrawal payable 75,797 6,480 Payable for investments purchased 28,132 62,440 Total liabilities 104,107 69,111 Total net assets managed by TS Hamilton Fund $ 1,919,568 $ 1,732,545

Reinsurance (Tables)

Reinsurance (Tables)	3 Months Ended
	Mar. 31, 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 for the three months ended March 31, 2024 and 2023: ($ in thousands) 2024 2023 Beginning balance $ 3,000 $ 2,856 Increase (decrease) in allowance (847) 280 Ending balance $ 2,153 $ 3,136
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 for the three months ended March 31, 2024 and 2023: ($ in thousands) 2024 2023 Beginning balance $ 687 $ 777 Provision for (release of) allowance 22 15 Ending balance $ 709 $ 792
Schedule of Paid and Unpaid Losses and Loss Adjustment Expenses Recoverable	At March 31, 2024 and December 31, 2023, 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 2024 2023 Collateralized 25.2 % 28.5 % A- or better 74.3 % 71.0 % Below A- 0.5 % 0.5 % Total 100.0 % 100.0 %

Reserve for Losses and Loss A_2

Reserve for Losses and Loss Adjustment Expenses (Tables)	3 Months Ended
	Mar. 31, 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 three months ended March 31, 2024 and 2023: ($ 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 220,295 144,556 Prior years 12,057 4,005 Total incurred 232,352 148,561 Net losses and loss adjustment expenses paid in respect of losses occurring in: Current year 3,336 7,936 Prior years 113,015 129,702 Total paid 116,351 137,638 Foreign currency revaluation and other (3,683) 9,894 Net unpaid losses and loss adjustment expenses, end of period 1,981,278 1,699,229 Reinsurance recoverable on unpaid losses 1,167,504 1,192,283 Gross unpaid losses and loss adjustment expenses, end of period $ 3,148,782 $ 2,891,512

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2024
Segment Reporting [Abstract]
Schedule of Segment Reporting Information	($ in thousands) Three Months Ended March 31, 2024 International Bermuda Corporate Total Gross premiums written $ 320,841 $ 401,100 $ — $ 721,941 Net premiums written $ 185,033 $ 329,847 $ — $ 514,880 Net premiums earned $ 196,814 $ 188,489 $ — $ 385,303 Third party fee income 3,586 3,892 — 7,478 Losses and loss adjustment expenses 116,162 116,190 — 232,352 Acquisition costs 47,720 36,834 — 84,554 Other underwriting expenses 31,203 12,150 — 43,353 Underwriting income (loss) $ 5,315 $ 27,207 $ — $ 32,522 Net realized and unrealized gains (losses) on investments 255,371 255,371 Net investment income (loss) 12,618 12,618 Net foreign exchange gains (losses) (2,125) (2,125) Corporate expenses (11,502) (11,502) Amortization of intangible assets (3,252) (3,252) Interest expense (5,708) (5,708) Income (loss) before income tax 277,924 Income tax (expense) benefit (592) (592) Net income (loss) 277,332 Net income (loss) attributable to non-controlling interest 120,158 120,158 Net income (loss) attributable to common shareholders $ 157,174 Key Ratios Attritional loss ratio - current year 56.0 % 58.4 % 57.2 % Attritional loss ratio - prior year development 2.9 % 3.2 % 3.1 % Catastrophe loss ratio - current year 0.0 % 0.0 % 0.0 % Catastrophe loss ratio - prior year development 0.1 % 0.0 % 0.0 % Loss and loss adjustment expense ratio 59.0 % 61.6 % 60.3 % Acquisition cost ratio 24.2 % 19.5 % 21.9 % Other underwriting expense ratio 14.0 % 4.4 % 9.3 % Combined ratio 97.2 % 85.5 % 91.5 % ($ in thousands) Three Months Ended March 31, 2023 International Bermuda Corporate Total Gross premiums written $ 247,114 $ 291,050 $ — $ 538,164 Net premiums written $ 122,019 $ 226,479 $ — $ 348,498 Net premiums earned $ 149,515 $ 134,387 $ — $ 283,902 Third party fee income 2,902 102 — 3,004 Losses and loss adjustment expenses 70,393 78,168 — 148,561 Acquisition costs 37,193 27,947 — 65,140 Other underwriting expenses 28,461 10,681 — 39,142 Underwriting income (loss) $ 16,370 $ 17,693 $ — $ 34,063 Net realized and unrealized gains (losses) on investments 35,133 35,133 Net investment income (loss) 2,359 2,359 Other income (loss), excluding third party fee income 29 29 Net foreign exchange gains (losses) (2,046) (2,046) Corporate expenses (6,664) (6,664) Amortization of intangible assets (2,770) (2,770) Interest expense (5,529) (5,529) Income (loss) before income tax 54,575 Income tax (expense) benefit (1,573) (1,573) Net income (loss) 53,002 Net income (loss) attributable to non-controlling interest 1,510 1,510 Net income (loss) attributable to common shareholders $ 51,492 Key Ratios Attritional loss ratio - current year 49.9 % 48.1 % 49.1 % Attritional loss ratio - prior year development (4.2) % 6.1 % 0.6 % Catastrophe loss ratio - current year 0.0 % 3.9 % 1.8 % Catastrophe loss ratio - prior year development 1.4 % 0.1 % 0.8 % Loss and loss adjustment expense ratio 47.1 % 58.2 % 52.3 % Acquisition cost ratio 24.9 % 20.8 % 22.9 % Other underwriting expense ratio 17.1 % 7.9 % 12.7 % Combined ratio 89.1 % 86.9 % 87.9 %
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 for the three months ended March 31, 2024 and 2023: ($ in thousands) 2024 2023 International Lloyd's of London $ 198,581 $ 148,709 Ireland 99,073 83,764 U.S. 23,187 14,641 Total International 320,841 247,114 Bermuda 401,100 291,050 Total $ 721,941 $ 538,164

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Schedule of Long-Term Debt Instruments	As at ($ in thousands) March 31, December 31, Outstanding loan balance $ 150,000 $ 150,000 Loan fair value 151,000 151,000 Unamortized loan issuance costs $ 141 $ 170
Schedule of Credit Facilities	The Company’s credit facilities at March 31, 2024, and associated securities pledged, were as follows: ($ in thousands) 2024 Available letter of credit and revolving loan facilities - commitments $ 995,000 Available letter of credit and revolving loan facilities - in use 745,958 Security pledged under letter of credit and revolving loan facilities: Pledged interests in TS Hamilton Fund $ 237,461 Pledged interests in fixed income portfolio 251,588 Cash 2,339

Share Capital (Tables)

Share Capital (Tables)	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Schedule of Share Capital	Hamilton Group’s share capital at March 31, 2024 and December 31, 2023, is comprised as follows: ($ in thousands) Authorized: Common shares of $0.01 par value each (2024 and 2023: 150,000,000) Issued, outstanding and fully paid: 2024 2023 Class A common shares (2024 and 2023: 28,644,807) $ 286 $ 286 Class B common shares (2024: 56,813,977 and 2023: 56,036,067) 568 560 Class C common shares (2024 and 2023: 25,544,229) 255 255 Total $ 1,109 $ 1,101
Schedule of Activity Related to Common Shares	The following is a summary of the activity related to common shares authorized for the three months ended March 31, 2024 and 2023: 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 Balance - March 31, 2024 28,644,807 72,337,352 25,544,229 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 Balance - March 31, 2023 53,993,690 50,480,684 30,525,626 — 135,000,000 The following is a summary of the activity related to common shares issued and outstanding for the three months ended March 31, 2024 and 2023: Class A Class B Class C Total Balance - December 31, 2023 28,644,807 56,036,067 25,544,229 110,225,103 Vesting of awards — 761,261 — 761,261 Exercise of warrants — 201,292 — 201,292 Director share awards granted — 20,383 — 20,383 Share repurchases — (205,026) — (205,026) Balance - March 31, 2024 28,644,807 56,813,977 25,544,229 111,003,013 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 — 24,780 — 24,780 Share repurchases — (117,210) — (117,210) Balance - March 31, 2023 30,520,078 42,684,738 30,525,626 103,730,442

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 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 for the three months ended March 31, 2024 and 2023, respectively: ($ in thousands, except per share information) 2024 2023 Numerator: Net income (loss) attributable to common shareholders $ 157,174 $ 51,492 Denominator: Weighted average common shares outstanding - basic 110,921 103,732 Effect of dilutive securities 3,325 893 Weighted average common shares outstanding - diluted 114,246 104,625 Basic income (loss) per share attributable to common shareholders $ 1.42 $ 0.50 Diluted income (loss) per share attributable to common shareholders $ 1.38 $ 0.49

Organization (Details)

Organization (Details) - USD ($) $ in Millions	Nov. 14, 2023	Jul. 01, 2023	Jun. 30, 2023
Schedule of Equity Method Investments [Line Items]
Proceeds from the IPO	$ 80.6
Two Sigma Hamilton Fund, LLC | Hamilton Re
Schedule of Equity Method Investments [Line Items]
Commitment for investment in Two Sigma Funds		$ 1,800
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	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 2,277,364	$ 2,294,936
Gross Unrealized Gains	7,573	17,667
Gross Unrealized Losses	(55,739)	(52,457)
Investments, at fair value	2,229,198	2,260,146
U.S. government treasuries
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	636,151	717,134
Gross Unrealized Gains	782	5,137
Gross Unrealized Losses	(15,682)	(14,021)
Investments, at fair value	621,251	708,250
U.S. states, territories and municipalities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	4,481	4,656
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(253)	(286)
Investments, at fair value	4,228	4,370
Non-U.S. sovereign governments and supranationals
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	62,211	55,662
Gross Unrealized Gains	977	2,175
Gross Unrealized Losses	(1,199)	(1,591)
Investments, at fair value	61,989	56,246
Corporate
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	918,909	877,493
Gross Unrealized Gains	4,290	8,443
Gross Unrealized Losses	(21,816)	(22,060)
Investments, at fair value	901,383	863,876
Residential mortgage-backed securities - Agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	232,441	180,661
Gross Unrealized Gains	340	435
Gross Unrealized Losses	(15,000)	(12,583)
Investments, at fair value	217,781	168,513
Residential mortgage-backed securities - Non-agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	6,124	5,639
Gross Unrealized Gains	9	16
Gross Unrealized Losses	(711)	(671)
Investments, at fair value	5,422	4,984
Commercial mortgage-backed securities - Non-agency
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	33,321	11,473
Gross Unrealized Gains	85	0
Gross Unrealized Losses	(936)	(1,050)
Investments, at fair value	32,470	10,423
Other asset-backed securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	32,691	14,781
Gross Unrealized Gains	56	20
Gross Unrealized Losses	(141)	(195)
Investments, at fair value	32,606	14,606
Total fixed maturities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,926,329	1,867,499
Gross Unrealized Gains	6,539	16,226
Gross Unrealized Losses	(55,738)	(52,457)
Investments, at fair value	1,877,130	1,831,268
Short-term investments
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	351,035	427,437
Gross Unrealized Gains	1,034	1,441
Gross Unrealized Losses	(1)	0
Investments, at fair value	$ 352,068	$ 428,878

Investments - Schedule of Contr

Investments - Schedule of Contractual Maturities of Fixed Maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Amortized Cost
Amortized Cost	$ 2,277,364	$ 2,294,936
Fair Value
Fair Value	2,229,198	2,260,146
Total fixed maturities
Amortized Cost
Amortized Cost	1,926,329	1,867,499
Fair Value
Fair Value	1,877,130	$ 1,831,268
Fixed Maturities, Excluding Mortgage-backed and Asset-backed Securities
Amortized Cost
Due less than one year	137,552
Due after one through five years	1,264,516
Due after five through ten years	216,276
Due after ten years	3,408
Fair Value
Due less than one year	134,603
Due after one through five years	1,236,870
Due after five through ten years	214,483
Due after ten years	2,895
Mortgage-backed
Amortized Cost
Mortgage/Asset-backed	271,886
Fair Value
Mortgage/Asset-backed	255,673
Asset-backed
Amortized Cost
Mortgage/Asset-backed	32,691
Fair Value
Mortgage/Asset-backed	$ 32,606

Investments - Schedule of Inves

Investments - Schedule of Investments in Two Sigma Funds (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Marketable Securities [Line Items]
Cost	$ 753,967	$ 770,191
Investments in Two Sigma Funds, at fair value	953,659	851,470
Two Sigma Funds
Marketable Securities [Line Items]
Net Unrealized Gains (Losses)	199,692	81,279
Investments in Two Sigma Funds, at fair value	953,659	851,470
Two Sigma Futures Portfolio, LLC (FTV)
Marketable Securities [Line Items]
Cost	337,916	433,911
Net Unrealized Gains (Losses)	59,294	(38,105)
Investments in Two Sigma Funds, at fair value	397,210	395,806
Two Sigma Spectrum Portfolio, LLC (STV)
Marketable Securities [Line Items]
Cost	246,490	193,299
Net Unrealized Gains (Losses)	91,849	88,228
Investments in Two Sigma Funds, at fair value	338,339	281,527
Two Sigma Equity Spectrum Portfolio, LLC (ESTV)
Marketable Securities [Line Items]
Cost	169,561	142,981
Net Unrealized Gains (Losses)	48,549	31,156
Investments in Two Sigma Funds, at fair value	$ 218,110	$ 174,137

Investments - Narrative (Detail

Investments - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 01, 2023	Mar. 31, 2024	Mar. 31, 2023	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Net Investment Income [Line Items]
Management fees		$ 11,950	$ 12,333
Restricted cash and cash equivalents		95,565			$ 106,351
Cash, cash equivalents and restricted cash		1,180,603	1,084,815		900,860	$ 1,207,203
Cash and cash equivalents		1,085,038			794,509
Capital Requirements | Asset Pledged as Collateral
Net Investment Income [Line Items]
Investments, fair value		237,000			232,200
Restricted cash and cash equivalents		1,600			7,200
Trust Accounts | Asset Pledged as Collateral
Net Investment Income [Line Items]
Investments, fair value		54,100			54,100
Restricted cash and cash equivalents		1,400			1,500
Underwriting Obligations | Asset Pledged as Collateral
Net Investment Income [Line Items]
Investments, fair value		36,700			37,200
Restricted cash and cash equivalents		92,300			97,400
Escrow Funds | Asset Pledged as Collateral
Net Investment Income [Line Items]
Restricted cash and cash equivalents		300			300
TS Hamilton Fund
Net Investment Income [Line Items]
Management fee percentage	2.50%			3%
Management fees		11,400	11,900
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		120,100	$ 1,500
Cash and cash equivalents		$ 706,969			$ 479,255
TS Hamilton Fund | Hamilton Re
Net Investment Income [Line Items]
Initial term		3 years
Capital account withdrawal, monthly liquidity, number of calendar days prior to month end		15 days
Capital account withdrawal, daily liquidity, number of business day's written notice		1 day
Two Sigma Futures Portfolio, LLC (FTV)
Net Investment Income [Line Items]
Percentage of ownership in funds		17.70%
Two Sigma Spectrum Portfolio, LLC (STV)
Net Investment Income [Line Items]
Percentage of ownership in funds		18.70%
Two Sigma Equity Spectrum Portfolio, LLC (ESTV)
Net Investment Income [Line Items]
Percentage of ownership in funds		10.20%
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	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Net Investment Income [Line Items]
Investments in Two Sigma Funds, at fair value	$ 953,659	$ 851,470
TS Hamilton Fund
Net Investment Income [Line Items]
Investments in Two Sigma Funds, at fair value	$ 953,659	$ 851,470
US Treasury Securities, Maturing 2024-2054 | TS Hamilton Fund | Long
Net Investment Income [Line Items]
Principal / Shares	996,048
Investments in Two Sigma Funds, at fair value	$ 987,600
US Treasury Securities, Maturing 2024-2054 | Members' Equity | Investment Concentration Risk | TS Hamilton Fund | Long
Net Investment Income [Line Items]
% of Members' Equity	51.50%
State Street Treasury Obligations Money Market Fund | TS Hamilton Fund | Long
Net Investment Income [Line Items]
Principal / Shares	172,946
Investments in Two Sigma Funds, at fair value	$ 172,946
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%
US Treasury Securities, Maturing 2027-2054 | TS Hamilton Fund | Short
Net Investment Income [Line Items]
Principal / Shares	41,401
Investments in Two Sigma Funds, at fair value	$ 41,033
US Treasury Securities, Maturing 2027-2054 | Members' Equity | Investment Concentration Risk | TS Hamilton Fund | Short
Net Investment Income [Line Items]
% of Members' Equity	2.10%

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
	Mar. 31, 2024	Mar. 31, 2023
Net realized and unrealized gains (losses) on investments:
Net realized gains (losses) on investments	$ 149,445	$ (37,651)
Change in net unrealized gains (losses) on investments	105,926	72,784
Net realized and unrealized gains (losses) on investments	255,371	35,133
Net investment income (loss):
Interest and other	24,831	14,928
Management fees	(11,950)	(12,333)
Other expenses	(263)	(236)
Net investment income (loss)	12,618	2,359
Total net realized and unrealized gains (losses) on investments and net investment income (loss)	267,989	37,492
Total fixed maturities
Net investment income (loss):
Interest and other	16,950	8,155
Short-term investments
Net investment income (loss):
Interest and other	(1)
Interest and other		153
TS Hamilton Fund
Net realized and unrealized gains (losses) on investments:
Net realized gains (losses) on investments	152,387	(31,970)
Change in net unrealized gains (losses) on investments	118,917	50,227
Net investment income (loss):
Interest and other	3,015	3,888
Cash and cash equivalents
Net investment income (loss):
Interest and other	4,115	2,309
Other
Net investment income (loss):
Interest and other	752	423
Fixed maturities and short-term investments
Net realized and unrealized gains (losses) on investments:
Net realized gains (losses) on investments	(2,942)	(5,681)
Change in net unrealized gains (losses) on investments	$ (12,991)	$ 22,557

Fair Value (Details)

Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	$ 2,229,198	$ 2,260,146
U.S. government treasuries
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	621,251	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	4,228	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	61,989	56,246
Corporate
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	901,383	863,876
Residential mortgage-backed securities - Agency
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	217,781	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	5,422	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	32,470	10,423
Other asset-backed securities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	32,606	14,606
Total fixed maturities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	1,877,130	1,831,268
Short-term investments
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	352,068	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 | 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 | Total fixed maturities
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	2,229,198	2,260,146
Level 2 | U.S. government treasuries
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	621,251	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	4,228	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	61,989	56,246
Level 2 | Corporate
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	901,383	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	217,781	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	5,422	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	32,470	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	32,606	14,606
Level 2 | Total fixed maturities
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	1,877,130	1,831,268
Level 2 | Short-term investments
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Investments, at fair value	352,068	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 | 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 | Total fixed maturities
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
	Mar. 31, 2024	Mar. 31, 2023
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Balance - beginning of period	$ 133
Balance - end of period	54,727
TS Hamilton Fund
Equity, Attributable to Noncontrolling Interest [Roll Forward]
Balance - beginning of period	133	$ 119
Withdrawals	(65,564)	(1,509)
Equity in earnings	21	1
Incentive allocation	120,137	1,509
Balance - end of period	$ 54,727	$ 120

Variable Interest Entities - _2

Variable Interest Entities - Schedule of Total Assets and Total Liabilities of TS Hamilton Fund (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets
Cash and cash equivalents	$ 1,085,038	$ 794,509
Short-term investments	2,229,198	2,260,146
Investments in Two Sigma Funds, at fair value	953,659	851,470
Receivables for investments sold	17,777	42,419
Total assets	7,349,025	6,671,355
Liabilities
Accounts payable and accrued expenses	155,684	186,887
Payables for investments purchased	55,071	66,606
Total liabilities	5,084,793	4,623,372
Short-term investments
Assets
Short-term investments	352,068	428,878
TS Hamilton Fund
Assets
Cash and cash equivalents	706,969	479,255
Investments in Two Sigma Funds, at fair value	953,659	851,470
Receivables for investments sold	13,868	41,087
Interest and dividends receivable	1,024	966
Total assets	2,023,675	1,801,656
Liabilities
Accounts payable and accrued expenses	178	191
Withdrawal payable	75,797	6,480
Payables for investments purchased	28,132	62,440
Total liabilities	104,107	69,111
Total net assets managed by TS Hamilton Fund	1,919,568	1,732,545
TS Hamilton Fund | Short-term investments
Assets
Short-term investments	$ 348,155	$ 428,878

Reinsurance - Narrative (Detail

Reinsurance - Narrative (Details) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended		12 Months Ended
	Feb. 06, 2020	Dec. 31, 2023	Dec. 31, 2020	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Ceded Credit Risk [Line Items]
Premiums receivable balance, credit provisions		$ 3,000		$ 2,153	$ 3,136	$ 3,000	$ 2,856
Premiums receivable		658,363		856,111		658,363
Paid losses recoverable		145,202		169,469		145,202
Unpaid losses and loss adjustment expenses recoverable		1,161,077		1,167,504	1,192,283	1,161,077	1,177,863
Reinsurance recoverable, provisions		687		709	792	687	$ 777
Reinsurance premiums ceded				207,061	189,666
Related Party
Ceded Credit Risk [Line Items]
Reinsurance premiums ceded				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		47,300		$ 49,800
Reinsurance premiums ceded	$ 72,100
Amortization of the deferred gain				$ 900	$ 200
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				25%		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				22%		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				12%		12%

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	3 Months Ended	12 Months Ended
	Mar. 31, 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	74.30%	71%
Below A-
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable	0.50%	0.50%
Collateralized
Ceded Credit Risk [Line Items]
% of total paid and unpaid losses and loss adjustment expenses recoverable	25.20%	28.50%

Reinsurance - Schedule of Rollf

Reinsurance - Schedule of Rollforward of Provision of Company's Premiums Receivable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Schedule of Accounts, Notes, Loans and Financing Receivable [Rollforward]
Beginning balance	$ 3,000	$ 2,856
Increase (decrease) in allowance	(847)	280
Ending balance	$ 2,153	$ 3,136

Reinsurance - Schedule of Rol_2

Reinsurance - Schedule of Rollforward of Provision of Company's Reinsurance Recoverable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Schedule of Accounts, Notes, Loans and Financing Receivable [Rollforward]
Beginning balance	$ 687	$ 777
Provision for (release of) allowance	22	15
Ending balance	$ 709	$ 792

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
	Mar. 31, 2024	Mar. 31, 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	220,295	144,556
Prior years	12,057	4,005
Total incurred	232,352	148,561
Net losses and loss adjustment expenses paid in respect of losses occurring in:
Current year	3,336	7,936
Prior years	113,015	129,702
Total paid	116,351	137,638
Foreign currency revaluation and other	(3,683)	9,894
Net unpaid losses and loss adjustment expenses, end of period	1,981,278	1,699,229
Reinsurance recoverable on unpaid losses	1,167,504	1,192,283
Gross unpaid losses and loss adjustment expenses, end of period	$ 3,148,782	$ 2,891,512

Reserve for Losses and Loss A_4

Reserve for Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)	$ 12,057	$ 4,005
Acquisition costs	84,554	65,140
Reserve for losses and loss adjustment expenses	3,148,782	2,891,512	$ 3,030,037	$ 2,856,275
Baltimore Bridge
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expenses	37,900		0
Ukrainian Conflict
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expenses	64,400		64,900
Covid-19
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expenses	15,800		$ 14,100
Specialty Contracts
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)	11,400	(5,400)
Casualty Lines
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)	4,000	(1,000)
Property Contracts
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)	(2,500)	12,100
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)	(800)	(1,800)
Amortization of the associated deferred gain	900
Net reserves for losses and loss adjustment expenses	$ (100)
Attritional Losses
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)		1,800
Catastrophe Losses
Liability for Claims and Claims Adjustment Expense [Line Items]
Net prior year development, unfavorable (favorable)		$ 2,200

Segment Reporting - Schedule of

Segment Reporting - Schedule of Segment Reporting Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) segment	Mar. 31, 2023 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2
Gross premiums written	$ 721,941	$ 538,164
Net premiums written	514,880	348,498
Net premiums earned	385,303	283,902
Third party fee income	7,478	3,004
Losses and loss adjustment expenses	232,352	148,561
Acquisition costs	84,554	65,140
Other underwriting expenses	43,353	39,142
Underwriting income (loss)	32,522	34,063
Net realized and unrealized gains (losses) on investments	255,371	35,133
Net investment income (loss)	12,618	2,359
Other income (loss), excluding third party fee income		29
Net foreign exchange gains (losses)	(2,125)	(2,046)
Corporate expenses	(11,502)	(6,664)
Amortization of intangible assets	(3,252)	(2,770)
Interest expense	(5,708)	(5,529)
Income (loss) before income tax	277,924	54,575
Income tax expense (benefit)	(592)	(1,573)
Net income (loss)	277,332	53,002
Net income (loss) attributable to non-controlling interest	120,158	1,510
Net income (loss) and other comprehensive income (loss) attributable to common shareholders	$ 157,174	$ 51,492
Attritional loss ratio - current year	57.20%	49.10%
Attritional loss ratio - prior year development	3.10%	0.60%
Catastrophe loss ratio - current year	0%	1.80%
Catastrophe loss ratio - prior year development	0%	0.80%
Loss and loss adjustment expense ratio	60.30%	52.30%
Acquisition cost ratio	21.90%	22.90%
Other underwriting expense ratio	9.30%	12.70%
Combined ratio	91.50%	87.90%
Operating Segments | International
Segment Reporting Information [Line Items]
Gross premiums written	$ 320,841	$ 247,114
Net premiums written	185,033	122,019
Net premiums earned	196,814	149,515
Third party fee income	3,586	2,902
Losses and loss adjustment expenses	116,162	70,393
Acquisition costs	47,720	37,193
Other underwriting expenses	31,203	28,461
Underwriting income (loss)	$ 5,315	$ 16,370
Attritional loss ratio - current year	56%	49.90%
Attritional loss ratio - prior year development	2.90%	(4.20%)
Catastrophe loss ratio - current year	0%	0%
Catastrophe loss ratio - prior year development	0.10%	1.40%
Loss and loss adjustment expense ratio	59%	47.10%
Acquisition cost ratio	24.20%	24.90%
Other underwriting expense ratio	14%	17.10%
Combined ratio	97.20%	89.10%
Operating Segments | Bermuda
Segment Reporting Information [Line Items]
Gross premiums written	$ 401,100	$ 291,050
Net premiums written	329,847	226,479
Net premiums earned	188,489	134,387
Third party fee income	3,892	102
Losses and loss adjustment expenses	116,190	78,168
Acquisition costs	36,834	27,947
Other underwriting expenses	12,150	10,681
Underwriting income (loss)	$ 27,207	$ 17,693
Attritional loss ratio - current year	58.40%	48.10%
Attritional loss ratio - prior year development	3.20%	6.10%
Catastrophe loss ratio - current year	0%	3.90%
Catastrophe loss ratio - prior year development	0%	0.10%
Loss and loss adjustment expense ratio	61.60%	58.20%
Acquisition cost ratio	19.50%	20.80%
Other underwriting expense ratio	4.40%	7.90%
Combined ratio	85.50%	86.90%
Corporate
Segment Reporting Information [Line Items]
Gross premiums written	$ 0	$ 0
Net premiums written	0	0
Net premiums earned	0	0
Third party fee income	0	0
Losses and loss adjustment expenses	0	0
Acquisition costs	0	0
Other underwriting expenses	0	0
Underwriting income (loss)	0	0
Net realized and unrealized gains (losses) on investments	255,371	35,133
Net investment income (loss)	12,618	2,359
Other income (loss), excluding third party fee income		29
Net foreign exchange gains (losses)	(2,125)	(2,046)
Corporate expenses	(11,502)	(6,664)
Amortization of intangible assets	(3,252)	(2,770)
Interest expense	(5,708)	(5,529)
Income tax expense (benefit)	(592)	(1,573)
Net income (loss) attributable to non-controlling interest	$ 120,158	$ 1,510

Segment Reporting - Schedule _2

Segment Reporting - Schedule of Gross Premiums Written by Geographical Location of Subsidiaries (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	$ 721,941	$ 538,164
Lloyd's of London
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	198,581	148,709
Ireland
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	99,073	83,764
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	23,187	14,641
Total International
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	320,841	247,114
Bermuda
Revenues from External Customers and Long-Lived Assets [Line Items]
Gross premiums written	$ 401,100	$ 291,050

Debt and Credit Facilities - Na

Debt and Credit Facilities - Narrative (Details) - USD ($)					3 Months Ended
	Oct. 27, 2023	Oct. 26, 2023	Aug. 11, 2023	Jun. 23, 2022	Mar. 31, 2024	Mar. 31, 2023	Aug. 08, 2023
Line of Credit Facility [Line Items]
Line of credit facility, outstanding					$ 745,958,000
Interest expense					5,708,000	$ 5,529,000
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
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
Unused commitment fee percentage				0.225%
Line of Credit | Unsecured Facility | Letter of Credit
Line of Credit Facility [Line Items]
Stated interest rate				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
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
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
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
Secured Overnight Financing Rate (SOFR) | Line of Credit | Unsecured Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate				1.85%

Debt and Credit Facilities - Sc

Debt and Credit Facilities - Schedule of Credit Facilities (Details) $ in Thousands	Mar. 31, 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	745,958
TS Hamilton Fund
Line of Credit Facility [Line Items]
Security pledged under letter of credit and revolving loan facilities:	237,461
Fixed Income Portfolio
Line of Credit Facility [Line Items]
Security pledged under letter of credit and revolving loan facilities:	251,588
Cash
Line of Credit Facility [Line Items]
Security pledged under letter of credit and revolving loan facilities:	$ 2,339

Debt and Credit Facilities - _2

Debt and Credit Facilities - Schedule of Company Compliance (Details) - Facility - Unsecured Debt - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Line of Credit Facility [Line Items]
Outstanding loan balance	$ 150,000	$ 150,000
Fair value of debt	151,000	151,000
Unamortized issuance costs	$ 141	$ 170

Share Capital - Schedule of Sha

Share Capital - Schedule of Share Capital (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 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	135,000,000	135,000,000
Common stock issued (in shares)	111,003,013	110,225,103	103,730,442	103,087,859
Common stock outstanding (in shares)	111,003,013	110,225,103	103,730,442	103,087,859
Common shares	$ 1,109	$ 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)	28,644,807	28,644,807	53,993,690	53,993,690
Common stock issued (in shares)	28,644,807	28,644,807	30,520,078	30,520,078
Common stock outstanding (in shares)	28,644,807	28,644,807	30,520,078	30,520,078
Common shares	$ 286	$ 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)	72,337,352	72,337,352	50,480,684	50,480,684
Common stock issued (in shares)	56,813,977	56,036,067	42,684,738	42,042,155
Common stock outstanding (in shares)	56,813,977	56,036,067	42,684,738	42,042,155
Common shares	$ 568	$ 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)	25,544,229	25,544,229	30,525,626	30,525,626
Common stock issued (in shares)	25,544,229	25,544,229	30,525,626	30,525,626
Common stock outstanding (in shares)	25,544,229	25,544,229	30,525,626	30,525,626
Common shares	$ 255	$ 255

Share Capital - Schedule of Com

Share Capital - Schedule of Common Stock Authorized (Details) - shares	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	150,000,000	135,000,000	135,000,000
Common shares - end of period (in shares)	150,000,000	150,000,000	135,000,000
Common Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	28,644,807	53,993,690	53,993,690
Common shares - end of period (in shares)	28,644,807	28,644,807	53,993,690
Common Class B
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	72,337,352	50,480,684	50,480,684
Common shares - end of period (in shares)	72,337,352	72,337,352	50,480,684
Common Class C
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	25,544,229	30,525,626	30,525,626
Common shares - end of period (in shares)	25,544,229	25,544,229	30,525,626
Unclassified Common Class
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares - beginning of period (in shares)	23,473,612	0	0
Common shares - end of period (in shares)	23,473,612	23,473,612	0

Share Capital - Schedule of C_2

Share Capital - Schedule of Common Stock Issued and Outstanding (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)	110,225,103	103,087,859
Common shares outstanding - beginning of period (in shares)	110,225,103	103,087,859
Vesting of awards (in shares)	761,261	735,013
Exercise of awards (in shares)	201,292
Director share awards granted (in shares)	20,383	24,780
Share repurchases (in shares)	(205,026)	(117,210)
Common shares issued - end of period (in shares)	111,003,013	103,730,442
Common shares outstanding - end of period (in shares)	111,003,013	103,730,442
Common Class A
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)	28,644,807	30,520,078
Common shares outstanding - beginning of period (in shares)	28,644,807	30,520,078
Vesting of awards (in shares)	0	0
Exercise of awards (in shares)	0
Director share awards granted (in shares)	0	0
Share repurchases (in shares)	0	0
Common shares issued - end of period (in shares)	28,644,807	30,520,078
Common shares outstanding - end of period (in shares)	28,644,807	30,520,078
Common Class B
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)	56,036,067	42,042,155
Common shares outstanding - beginning of period (in shares)	56,036,067	42,042,155
Vesting of awards (in shares)	761,261	735,013
Exercise of awards (in shares)	201,292
Director share awards granted (in shares)	20,383	24,780
Share repurchases (in shares)	(205,026)	(117,210)
Common shares issued - end of period (in shares)	56,813,977	42,684,738
Common shares outstanding - end of period (in shares)	56,813,977	42,684,738
Common Class C
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares issued - beginning of period (in shares)	25,544,229	30,525,626
Common shares outstanding - beginning of period (in shares)	25,544,229	30,525,626
Vesting of awards (in shares)	0	0
Exercise of awards (in shares)	0
Director share awards granted (in shares)	0	0
Share repurchases (in shares)	0	0
Common shares issued - end of period (in shares)	25,544,229	30,525,626
Common shares outstanding - end of period (in shares)	25,544,229	30,525,626

Share Capital - Narrative (Deta

Share Capital - Narrative (Details)	Mar. 31, 2024
Class of Stock [Line Items]
Percent of combined voting power, Class A and Class B	9.50%
Common Class B
Class of Stock [Line Items]
Percent of combined voting power, Class A and Class B	14.92%

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net income (loss) attributable to common shareholders	$ 157,174	$ 51,492
Denominator:
Weighted average common shares outstanding - basic (in shares)	110,921,000	103,732,000
Effect of dilutive securities (in shares)	3,325,000	893,000
Weighted average common shares outstanding - diluted (in shares)	114,246,000	104,625,000
Basic income (loss) per share attributable to common shareholders (in dollars per share)	$ 1.42	$ 0.50
Diluted income (loss) per share attributable to common shareholders (in dollars per share)	$ 1.38	$ 0.49
Anti-dilutive shares excluded from the calculation of diluted income (loss) per share (in shares)	0	0

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	May 10, 2024	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Share repurchases (in shares)		205,026	117,210
Common stock issued (in shares)		111,003,013	103,730,442	110,225,103	103,087,859
Common stock outstanding (in shares)		111,003,013	103,730,442	110,225,103	103,087,859
Common Class A
Subsequent Event [Line Items]
Share repurchases (in shares)		0	0
Common stock issued (in shares)		28,644,807	30,520,078	28,644,807	30,520,078
Common stock outstanding (in shares)		28,644,807	30,520,078	28,644,807	30,520,078
Subsequent Event | Forecast
Subsequent Event [Line Items]
Common stock issued (in shares)	101,878,284
Common stock outstanding (in shares)	101,878,284
Subsequent Event | Common Class A | Forecast
Subsequent Event [Line Items]
Share repurchases (in shares)	9,124,729
Shares acquired (in dollars per share)	$ 12
Share repurchases	$ 109.5