Argo Group International (ARGO-PA) 10-Q 14 Nov 24 2024 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2024	Nov. 14, 2024
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	1-15259
Entity Registrant Name	ARGO GROUP INTERNATIONAL HOLDINGS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	98-0214719
Entity Address, Address Line One	501 7th Avenue 7th Floor
Entity Address, City or Town	New York
Entity Address, Postal Zip Code	10018
Entity Address, State or Province	NY
City Area Code	210
Local Phone Number	321-8400
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		13
Entity Central Index Key	0001091748
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false
Guarantee of Argo Group U.S., Inc. 6.500% Senior Notes due 2042
Document Information [Line Items]
Title of 12(b) Security	6.500% Senior Notes due 2042 issued by Argo Group US, Inc. and The Guarantee With Respects Thereto
Trading Symbol	ARGD
Security Exchange Name	NYSE
Depositary Shares
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, Each Representing a 1/1000th Interest in 7.00% Resettable Fixed Rate Preferred Stock, Series A, Par Value $1.00 Per Share
Trading Symbol	ARGOPrA
Security Exchange Name	NYSE

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Investments:
Fixed maturities available-for-sale, at fair value (cost: $2,283.6 and $2,521.5, respectively; allowance for expected credit losses: $1.0 and $0.2, respectively)	$ 2,368.2	$ 2,585.4
Equity securities, at fair value (cost: $56.7 and $11.7, respectively)	85.3	10.7
Other investments (cost: $425.9 and $311.0, respectively)	430.3	311
Short-term investments, at fair value (cost: $656.7 and $429.0, respectively)	657.1	429.5
Total investments	3,976	3,481.2
Cash, restricted cash and cash equivalents	558	791.6
Accrued investment income	19.8	20.4
Premiums receivable	191.7	230.7
Reinsurance recoverables	3,130.7	2,959.3
Other intangible assets, net of accumulated amortization	149.5	180.6
Current income taxes receivable, net	22.6	53.1
Deferred tax asset, net	65.9	39.1
Deferred acquisition costs, net	51.7	7.2
Ceded unearned premiums	384.8	356
Operating lease right-of-use assets	49.3	51.2
Other assets	171	189.1
Value of business acquired, net of accumulated amortization	45.6	143.6
Total assets	8,816.6	8,503.1
Liabilities and Stockholders' Equity
Reserves for losses and loss adjustment expenses	5,792.9	5,544.5
Unearned premiums	839.4	916.6
Accrued underwriting expenses and other liabilities	109	73.9
Ceded reinsurance payable, net	211.8	192.7
Funds held	44.5	57.3
Senior unsecured fixed rate notes	128.7	128
Junior subordinated debentures	242.7	241.2
Operating lease liabilities	50.5	51.4
Total liabilities	7,419.5	7,205.6
Commitments and contingencies (Note 12)
Stockholders' equity:
Series A Preferred stock and additional paid-in capital ($1.00 par; 10,000 and 30,000,000 shares authorized, respectively; 6,000 shares issued; liquidation preference $25,000)	137.1	137.1
Common stock ($0.01 and $1.00 par, respectively; 1,000 and 2,000,000,000 shares authorized, respectively; 13 and 1,056,638,730 shares issued, respectively)	0	1,056.6
Additional paid-in capital	1,292.4	51.1
Retained earnings (Accumulated deficit)	(101)	0.9
Accumulated other comprehensive income, net of taxes	68.6	51.8
Total stockholders' equity	1,397.1	1,297.5
Total liabilities and stockholders' equity	8,816.6	8,503.1
Mortgage Loans
Investments:
Loans	234.9	144.6
Private Loans
Investments:
Loans	$ 200.2	$ 0

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fixed maturities available-for-sale, at cost	$ 2,283.6	$ 2,521.5
Fixed maturities, allowance for expected credit losses	1	0.2
Loans, at cost	234.9	144.8
Equity securities, cost	56.7	11.7
Other investments, cost	425.9	311
Short-term investments, cost	$ 656.7	$ 429
Preferred shares par value (in dollars per share)	$ 1	$ 1
Preferred shares, shares authorized (in shares)	10,000	30,000,000
Preferred shares, shares issued (in shares)	6,000	6,000
Liquidation preference (in dollars per share)	$ 25,000	$ 25,000
Common shares, par value (in dollars per share)	$ 0.01	$ 1
Common shares, shares authorized (in shares)	1,000	2,000,000,000
Common shares, shares issued (in shares)	13	1,056,638,730
Mortgage Loans
Loans, at cost	$ 234.9	$ 144.8
Loans, Allowance for credit loss	0.7	0.2
Private Loans
Loans, at cost	200.7	0
Loans, Allowance for credit loss	$ 0.5	$ 0

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Premiums and other revenue:
Net earned premiums	$ 234.3	$ 342.7	$ 837.9	$ 1,062.5
Net investment income	62.3	40.4	187.1	102.9
Net investment and other gains (losses):
Net realized investment and other (losses) gains	0.8	7.4	5.8	(21)
Change in fair value recognized	0	(10.1)	26.4	2.1
Change in allowance for credit losses on fixed maturity securities	(1)	(2)	(1.4)	(2.1)
Total net investment and other gains (losses)	(0.2)	(4.7)	30.8	(21)
Total revenue	296.4	378.4	1,055.8	1,144.4
Expenses:
Losses and loss adjustment expenses	346.8	280.9	793.5	806.9
Underwriting, acquisition and general expenses	110.9	116.1	344.8	364
Non-operating expenses (income)	(0.2)	5.1	12.7	23.5
Interest expense	9.4	8.7	29.2	25.4
Fee and other expense (income), net	0	0.2	(0.1)	(0.3)
Foreign currency exchange (gains) losses	(3.8)	(3.3)	(3.1)	0.1
Total expenses	463.1	407.7	1,177	1,219.6
Income (loss) before income taxes	(166.7)	(29.3)	(121.2)	(75.2)
Income tax provision (benefit)	(34.4)	17.6	(27.2)	3.3
Net income (loss)	(132.3)	(46.9)	(94)	(78.5)
Dividends on Series A Preferred stock	2.6	2.6	7.9	7.9
Net income (loss) attributable to common stockholders	(134.9)	(49.5)	(101.9)	(86.4)
Net income (loss) attributable to common stockholders	$ (134.9)	$ (49.5)	$ (101.9)	$ (86.4)
Net income (loss) attributable to common stockholders per share of common stock:
Basic (in dollars per share)		$ (1.41)		$ (2.46)
Diluted (in dollars per share)		(1.41)		(2.46)
Dividend declared per common share (in dollars per share)		$ 0		$ 0
Weighted average common stock:
Basic (in shares)		35,197,824		35,158,416
Diluted (in shares)		35,197,824		35,158,416

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (132.3)	$ (46.9)	$ (94)	$ (78.5)
Foreign currency translation:
Foreign currency translation adjustments	0.4	0.5	0.3	1
Defined benefit pension plans:
Net gain arising during the period	0	0	0	1
Fixed maturity securities:
Unrealized gains (losses) arising during the period	50.9	(20.7)	25.7	(0.7)
Reclassification adjustment for losses (gains) included in net income (loss)	1.6	1.5	(4.8)	27.4
Other comprehensive income (loss) before tax	52.9	(18.7)	21.2	28.7
Defined benefit pension plans:
Net gain arising during the period	0	0	0	0.2
Fixed maturity securities:
Unrealized gains (losses) arising during the period	10.9	(3.3)	5.4	(0.3)
Reclassification adjustment for losses (gains) included in net income	0.3	(0.4)	(1)	5
Income tax provision (benefit) related to other comprehensive income (loss)	11.2	(3.7)	4.4	4.9
Other comprehensive income (loss), net of tax	41.7	(15)	16.8	23.8
Comprehensive income (loss)	$ (90.6)	$ (61.9)	$ (77.2)	$ (54.7)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Millions		Total	Preferred Stock and Additional Paid-in Capital	Common Stock	Additional Paid-In Capital	Treasury Shares	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2022		$ 1,232.9	$ 144	$ 46.4	$ 1,395.4	$ (455.1)	$ 407.3	$ (305.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(78.5)					(78.5)
Other comprehensive (loss) income - change in fair value of fixed maturities, net of taxes		22						22
Other comprehensive income, net of tax		1.8						1.8
Activity under stock incentive plans		0.5		0.1	0.4
Retirement of common stock (tax payments on equity compensation)		(0.9)			(0.9)
Employee stock purchase plan		1.2			1.2
Dividends on preferred stock and Series A Preferred stock		(7.9)					(7.9)
Cash dividend declared - common stock		0.2					0.2
Ending Balance at Sep. 30, 2023		1,171.3	144	46.5	1,396.1	(455.1)	321.1	(281.3)
Beginning Balance at Jun. 30, 2023		1,234.8	144	46.5	1,395.1	(455.1)	370.6	(266.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(46.9)					(46.9)
Other comprehensive (loss) income - change in fair value of fixed maturities, net of taxes		(15.5)						(15.5)
Other comprehensive income, net of tax		0.5						0.5
Activity under stock incentive plans		0.7			0.7
Retirement of common stock (tax payments on equity compensation)		(0.1)			(0.1)
Employee stock purchase plan		0.4			0.4
Dividends on preferred stock and Series A Preferred stock		(2.6)					(2.6)
Ending Balance at Sep. 30, 2023		1,171.3	144	46.5	1,396.1	(455.1)	321.1	(281.3)
Beginning Balance at Dec. 31, 2023		1,297.5	137.1	1,056.6	51.1	0	0.9	51.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(94)					(94)
Other comprehensive (loss) income - change in fair value of fixed maturities, net of taxes		16.5						16.5
Other comprehensive income, net of tax		0.3						0.3
Purchase accounting adjustments	[1]	(15.3)			(15.3)
Changes in common stock due to merger with AGIH Merger Sub, Inc.	[2]	0		(1,256.6)	1,256.6
Dividends on preferred stock and Series A Preferred stock		(7.9)					(7.9)
Issuance of common stock		200		200
Ending Balance at Sep. 30, 2024		1,397.1	137.1	0	1,292.4	0	(101)	68.6
Beginning Balance at Jun. 30, 2024		1,505.6	137.1	1,256.6	51.1	0	33.9	26.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		(132.3)					(132.3)
Other comprehensive (loss) income - change in fair value of fixed maturities, net of taxes		41.3						41.3
Other comprehensive income, net of tax		0.4						0.4
Purchase accounting adjustments	[3]	(15.3)			(15.3)
Changes in common stock due to merger with AGIH Merger Sub, Inc.	[4]	0		(1,256.6)	1,256.6
Dividends on preferred stock and Series A Preferred stock		(2.6)					(2.6)
Ending Balance at Sep. 30, 2024		$ 1,397.1	$ 137.1	$ 0	$ 1,292.4	$ 0	$ (101)	$ 68.6
[1] (2) Refer to the Merger with AGIH Merger Sub, Inc. in Note 1, “Business and Significant Accounting Policies” for additional information. (1) Impact of measurement period adjustment on bargain purchase in connection with the Merger. R efer to Note 1, “Business and Significant Accounting Policies” for additional information. (1) Impact of measurement period adjustment on bargain purchase in connection with the Merger. R efer to Note 1, “Business and Significant Accounting Policies” for additional information. (2) Refer to the Merger with AGIH Merger Sub, Inc. in Note 1, “Business and Significant Accounting Policies” for additional information.

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Parenthetical) - $ / shares	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Statement of Stockholders' Equity [Abstract]
Dividend declared per common share (in dollars per share)	$ 0	$ 0

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows provided by (used in) operating activities:
Net income (loss)	$ (94)	$ (78.5)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Amortization and depreciation	138.3	11.3
Share-based payments expense	0	0.3
Deferred income tax expense (benefit), net	(26.5)	4.7
Net investment and other (gains) losses	(30.8)	21
Undistributed earnings from alternative investment portfolio	(16.9)	(9.3)
Foreign currency exchange (gains) losses	(3.1)	0.1
Change in:
Accrued investment income	0.6	(1.6)
Receivables	(132.4)	743.4
Deferred acquisition costs	(44.5)	(10.7)
Ceded unearned premiums	(28.8)	(19.5)
Reserves for losses and loss adjustment expenses	232.1	(223.8)
Unearned premiums	(77.2)	(10.6)
Ceded reinsurance payable and funds held	6.3	(55.8)
Income taxes	30.5	(1.7)
Accrued underwriting expenses and other liabilities	33.4	(46.6)
Other, net	(70.6)	(51.2)
Cash (used in) provided by operating activities	(83.6)	271.5
Cash flows provided by (used in) investing activities:
Sales of fixed maturity investments	110.3	21.4
Maturities and mandatory calls of fixed maturity investments	398.4	119.5
Sales of equity securities	2.8	45.7
Sales of other investments	68.9	21.5
Purchases of fixed maturity investments	(224)	(11.9)
Purchases of equity securities	(48.6)	(0.3)
Purchases of other investments	(171.3)	(16.6)
Change in short-term investments	(200.3)	(566.4)
Settlements of foreign currency exchange forward contracts	0.8	4.5
Proceeds from business divestitures, net of cash transferred	0	62.9
Purchases of fixed assets, net	0	(2.4)
Cash used in investing activities	(342.1)	(322.1)
Cash flows provided by (used in) financing activities:
Debt borrowings	100	0
Repayment of debt	(100)	0
Issuance of common stock	200	0
Activity under stock incentive plans	0	1.2
Payment of cash dividends to preferred stockholders	(7.9)	(7.9)
Payment of cash dividends to common stockholders	0	0.2
Cash provided by (used in) financing activities	192.1	(6.5)
Effect of exchange rate changes on cash	0	0.3
Net change in cash and restricted cash including balances classified as held-for-sale	(233.6)	(56.8)
Net change in cash balances classified as held-for-sale	0	70.8
Cash, restricted cash, and cash equivalents, beginning of period	791.6	50.2
Cash, restricted cash, and cash equivalents, end of period	558	64.2
Mortgage Loans
Cash flows provided by (used in) investing activities:
Proceeds from loans	19.9	0
Purchase of loans	(108.3)	0
Private Loans
Cash flows provided by (used in) investing activities:
Proceeds from loans	15.3	0
Purchase of loans	$ (206)	$ 0

Business and Significant Accoun

Business and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Significant Accounting Policies	Business and Significant Accounting Policies The accompanying Condensed Consolidated Financial Statements of Argo Group International Holdings, Inc. and its subsidiaries (“Argo Group,” “we,” “us,” “our” or the “Company”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Argo Group is an underwriter of specialty insurance products in the property and casualty market. On November 16, 2023, we merged with Brookfield Wealth Solutions Ltd. (formerly known as Brookfield Reinsurance Ltd.), which resulted in a change to the Company’s ownership (the “Merger”). Brookfield Wealth Solutions Ltd. elected to push-down its purchase accounting, which resulted in the Company reflecting the fair market value of our assets and liabilities as of November 16, 2023, in accordance with Accounting Standards Codification (“ASC”) 805, Business Combinations. The application of push-down accounting created a new basis of accounting for all of our assets and liabilities. As such, the Company’s financial position, results of operations, and cash flows subsequent to the acquisition are not comparable with those prior to November 16, 2023, and therefore have been separated to indicate pre-acquisition and post-acquisition periods. The pre-acquisition period through November 15, 2023 is referred to as the Predecessor. The post-acquisition period, November 16, 2023 and forward, includes the impact of push-down accounting and is referred to as the Successor. The preparation of interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The major estimates reflected in our Condensed Consolidated Financial Statements include, but are not limited to, reserves for losses and loss adjustment expenses; reinsurance recoverables, including the reinsurance recoverables allowance for expected credit losses; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of intangibles, including those identified as part of purchase accounting related to the Merger, and our deferred tax asset valuation allowance. Actual results could materially differ from those estimates. Certain financial information that is normally included in annual Condensed Consolidated Financial Statements, including certain financial statement footnotes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the Condensed Consolidated Financial Statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2023 filed with the Securities and Exchange Commission ("SEC") (the “2023 Form 10-K”). The interim financial information as of, and for the three and nine months ended, September 30, 2024 and 2023 is unaudited. However, in the opinion of management, the interim information includes all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the results presented for the interim periods. The operating results for the interim periods are not necessarily indicative of the results to be expected for the full year. All material intercompany amounts have been eliminated in consolidation. Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation. Merger with AGIH Merger Sub, Inc. On September 25, 2024, the Company and AGIH Merger Sub, Inc., a Delaware corporation and wholly-owned subsidiary of the Company (“Merger Sub”), entered into an Agreement and Plan of Merger, pursuant to which, among other things, Merger Sub merged with and into the Company, with the Company continuing as the surviving corporation (the “Merger with AGIH Merger Sub, Inc.”). The purpose of the Merger with AGIH Merger Sub, Inc., was to reduce the Company’s annual franchise taxes in the State of Delaware by reducing the number of authorized shares of the Company’s common stock and preferred stock. In connection with the consummation of the Merger with AGIH Merger Sub, Inc., the number of authorized shares of the Company’s common stock decreased from 2,000,000,000 to 1,000, each share of the Company’s common stock, par value $1.00 per share, of the Company was converted into and became one hundred millionth (1/100,000,000) of a validly issued, fully paid, and non-assessable share of common stock, par value $0.01 per share, of the Company, and the number of authorized shares of the Company’s preferred stock decreased from 30,000,000 to 10,000. The merger constituted a common-control transaction as defined under current accounting standards as there was no change in control over the net assets of the Company. Therefore, these resulting financial statements reflect the financial position and results of operations as if the merger had occurred on January 1, 2024. Purchase Accounting Measurement Period Adjustment The Merger resulted in a $48.9 million bargain purchase, which is uncommon, since the value of the net assets acquired exceeded the purchase consideration. The values of certain assets and liabilities are considered preliminary in nature and are subject to adjustment during the measurement period as additional information is obtained. As the valuations are finalized, any changes to the preliminary valuation of assets acquired or liabilities assumed may result in retrospective adjustments to the provisional amounts recognized at the acquisition date to reflect new information obtained about facts and circumstances that existed as of the acquisition date that, if known, would have affected the measurement of the amounts recognized as of that date. During the three months ended September 30, 2024, the Company reduced its bargain purchase amount by $15.3 million to $33.6 million, resulting in a reduction to Additional paid-in capital . The adjustment related to the Company’s valuation of loss reserves for its U.S. Operations. Commutation of Riverstone Holdings Limited Reinsurance Agreement On June 2, 2024, the Company entered into a commutation with Riverstone Holdings Limited (part of the RiverStone International group) on its legacy assumed business from our former Malta operations, ArgoGlobal Holdings (Malta) Ltd., which was sold in 2022. This transaction had no material impact on our net income. The final consideration of $86.7 million was paid to Riverstone Holdings Limited on July 1, 2024. Sale of Argo Underwriting Agency Limited On September 8, 2022, Argo International Holdings Limited (the “Seller”), a wholly-owned subsidiary of the Company, and Ohio Farmers Insurance Company (the “Buyer”), part of the Westfield group of insurance companies, entered into a sale and purchase agreement (the “Transaction”) under which the Seller agreed to sell, and the Buyer agreed to purchase, the entire issued share capital of Argo Underwriting Agency Limited (“AUA”), for which the financial results are reported in our International segment. On February 2, 2023, the Seller completed the sale of the entire issued share capital of AUA. The Company received total consideration of $161.3 million, which included cash proceeds of $130.7 million as base consideration and an additional $30.6 million which was placed in escrow by the Buyer related to certain reinsurance-related recoverables. The funds in escrow may be released to the Seller over a period of two years following the closing. At the end of the two-year escrow period, any remaining balance of the escrow will be returned to the Buyer. Since the sale of AUA, $13.1 million of the consideration placed in escrow was released to the Company. As a result of the sale, we realized a loss of $20.3 million in the first quarter of 2023, which is included as a component of Net realized investment and other gains (losses) in our Condensed Consolidated Statements of Income (Loss). This loss is due to the realization of unrealized investment losses, which were previously a component of accumulated other comprehensive income.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	9 Months Ended
	Sep. 30, 2024
Accounting Policies [Abstract]
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements The Company evaluated recently issued accounting pronouncements and determined none are material to our results of operations or financial position reported herein.

Investments

Investments	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Investments	Investments As a result of the push-down accounting due to the Merger, the amortized cost of our investments is based on the fair value as of November 16, 2023. Fixed Maturities The amortized cost, gross unrealized gains, gross unrealized losses, allowance for credit losses, and fair value of fixed maturity investments were as follows: September 30, 2024 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 259.8 $ 5.2 $ 0.1 $ — $ 264.9 Foreign Governments 7.1 0.3 — — 7.4 Obligations of states and political subdivisions 82.2 3.0 — — 85.2 Corporate bonds 1,206.7 39.9 0.9 1.0 1,244.7 Commercial mortgage-backed securities 275.1 16.9 0.3 — 291.7 Residential mortgage-backed securities 204.9 13.7 — — 218.6 Asset-backed securities 104.9 3.5 — — 108.4 Collateralized loan obligations 142.9 4.4 — — 147.3 Total fixed maturities $ 2,283.6 $ 86.9 $ 1.3 $ 1.0 $ 2,368.2 December 31, 2023 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 357.7 $ 4.5 $ — $ — $ 362.2 Foreign Governments 27.9 2.6 — 0.2 30.3 Obligations of states and political subdivisions 92.4 2.0 — — 94.4 Corporate bonds 1,185.0 28.9 0.8 — 1,213.1 Commercial mortgage-backed securities 270.9 10.1 0.5 — 280.5 Residential mortgage-backed securities 235.2 13.6 — — 248.8 Asset-backed securities 140.4 1.7 0.1 — 142.0 Collateralized loan obligations 212.0 2.1 — — 214.1 Total fixed maturities $ 2,521.5 $ 65.5 $ 1.4 $ 0.2 $ 2,585.4 Contractual Maturity The amortized cost and fair values of fixed maturity investments as of September 30, 2024, by contractual maturity, were as follows: (in millions) Amortized Fair Due in one year or less $ 304.5 $ 306.4 Due after one year through five years 1,039.3 1,067.4 Due after five years through ten years 191.9 206.8 Due after ten years 20.1 21.6 Structured securities 727.8 766.0 Total $ 2,283.6 $ 2,368.2 The actual maturities may differ from the contractual maturities because debtors may have the right to call or prepay obligations. Other Investments Details regarding the carrying value and unfunded investment commitments of Other investments as of September 30, 2024 and December 31, 2023 were as follows: September 30, 2024 December 31, 2023 (in millions) Carrying Unfunded Carrying Unfunded Investment type Hedge funds $ 28.7 $ — $ 56.2 $ — Private equity 258.4 82.2 250.3 93.4 Real estate equity investments 101.0 — — — Other 42.2 30.4 4.5 — Total other investments $ 430.3 $ 112.6 $ 311.0 $ 93.4 The following describes each investment type: • Hedge funds: Hedge funds, carried at net asset value (“NAV”) as a practical expedient of fair value, include funds that primarily buy and sell stocks, including short sales, multi-strategy credit, relative value credit and distressed credit. • Private equity: Private equity includes limited partnership investments accounted for in accordance with the equity method of accounting and whose strategies include: buyout funds, real asset/infrastructure funds, credit special situations funds, mezzanine lending funds and direct investments and strategic non-controlling minority investments in private companies. • Real estate equity investments: Includes equity interests with underlying real estate investments accounted for in accordance with the equity method of accounting. • Other: Other primarily includes equity investments accounted for in accordance with the equity method of accounting and investments for which the Company has elected the fair value option of accounting. Unrealized Losses and Other-than-temporary Impairments An aging of unrealized losses on our investments in fixed maturities is presented below: September 30, 2024 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 17.9 $ 0.1 $ — $ — $ 17.9 $ 0.1 Corporate bonds 17.6 0.9 — — 17.6 0.9 Commercial mortgage-backed securities 19.2 0.3 — — 19.2 0.3 Total fixed maturities $ 54.7 $ 1.3 $ — $ — $ 54.7 $ 1.3 December 31, 2023 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities Foreign Governments $ 0.1 $ — $ — $ — $ 0.1 $ — Obligations of states and political subdivisions 0.5 — — — 0.5 — Corporate bonds 38.7 0.8 — — 38.7 0.8 Commercial mortgage-backed securities 32.2 0.5 — — 32.2 0.5 Residential mortgage-backed securities 2.9 — — — 2.9 — Asset-backed securities 11.4 0.1 — — 11.4 0.1 Collateralized loan obligations 21.4 — — — 21.4 — Total fixed maturities $ 107.2 $ 1.4 $ — $ — $ 107.2 $ 1.4 The Company holds a total of 1,152 fixed maturity securities, of which 51 were in an unrealized loss position for less than one year and none were in an unrealized loss position for a period of one year or greater as of September 30, 2024. The unrealized losses as of September 30, 2024 are primarily driven by interest rate movements. Allowance for Credit Losses For fixed maturities with a decline in fair value below the amortized cost due to credit-related factors, an allowance is established for the difference between the estimated recoverable value and amortized cost with a corresponding charge to Net investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss). The allowance is limited to the difference between amortized cost and fair value. The estimated recoverable value is the present value of cash flows expected to be collected, as determined by management. The difference between fair value and amortized cost that is not associated with credit-related factors is recognized in the Condensed Consolidated Statements of Comprehensive Income (Loss). Accrued interest is excluded from the measurement of the allowance for credit losses. When determining if a credit loss has been incurred, we may consider the historical performance of the security, available market information and security specific considerations such as the priority payment of the security. In addition, inputs used in our analysis include, but are not limited to, credit ratings and downgrades, delinquency rates, missed scheduled interest or principal payments, purchase yields, underlying asset performance, collateral types, modeled default rates, modeled severity rates, call/prepayment rates, expected cash flows, industry concentrations, and potential or filed bankruptcies or restructurings. In cooperation with our investment managers, we evaluate for credit losses each quarter utilizing a bottom up review approach. At the security level, a determination is made as to whether a decline in fair value below the amortized cost basis is due to credit-related or noncredit-related factors. If we determine that all or a portion of a fixed maturity is uncollectible, the uncollectible amortized cost is written off with a corresponding reduction to the allowance for credit losses. If we collect cash flows that were previously written off, the recovery is recognized in Net investment and other gains (losses) . We also consider whether we intend to sell an available-for-sale security or if it is more likely than not that we will be required to sell the security before recovery of its amortized cost. In these instances, a decline in fair value is recognized in Net investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss) based on the fair value of the security at the time of assessment, resulting in a new cost basis for the security. The following table presents a roll-forward of the changes in allowance for credit losses on available-for-sale fixed maturities by industry category for the three and nine months ended September 30, 2024 and 2023, respectively: Successor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, June 30, 2024 $ — $ — $ 0.5 $ — $ 0.5 Securities for which allowance was not previously recorded — — 0.2 — 0.2 Additional net increases (decreases) in existing allowance — — 0.3 — 0.3 Ending balance, September 30, 2024 $ — $ — $ 1.0 $ — $ 1.0 Predecessor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, June 30, 2023 $ 1.0 $ — $ 1.4 $ 0.1 $ 2.5 Securities for which allowance was not previously recorded — 0.5 1.4 — 1.9 Securities sold during the period — — (0.1) — (0.1) Additional net increases (decreases) in existing allowance 0.1 — — — 0.1 Ending balance, September 30, 2023 $ 1.1 $ 0.5 $ 2.7 $ 0.1 $ 4.4 Successor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2024 $ 0.2 $ — $ — $ — $ 0.2 Securities for which allowance was not previously recorded — — 0.6 — 0.6 Securities sold during the period — — (0.1) — (0.1) Additional net increases (decreases) in existing allowance (0.2) — 0.5 — 0.3 Ending balance, September 30, 2024 $ — $ — $ 1.0 $ — $ 1.0 Predecessor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2023 $ 0.7 $ 0.4 $ 1.6 $ 0.1 $ 2.8 Securities for which allowance was not previously recorded 0.1 0.5 2.1 — 2.7 Securities sold during the period — — (0.5) — (0.5) Additional net increases (decreases) in existing allowance 0.3 (0.4) (0.5) — (0.6) Ending balance, September 30, 2023 $ 1.1 $ 0.5 $ 2.7 $ 0.1 $ 4.4 For mortgage loans an allowance for credit losses is established at the time of origination or purchase, as necessary, and is updated each reporting period. Changes in the allowance for credit losses are recorded in Net investment and other gains (losses) . This allowance reflects the risk of loss, even when that risk is remote, that is expected over the remaining contractual life of the loan. The allowance for credit losses considers available relevant information about the collectability of cash flows, including information about past events, current conditions, and reasonable and supportable forecasts of future economic conditions. Mortgage Loans Mortgage loan investments are composed of participation interests in a portfolio of commercial and residential mortgage loans. Loan collateral is diversified with regard to property type and geography. The following table presents loans by property type: September 30, 2024 (in millions) Cost Composition Loan Count Residential $ 11.6 4.9 % 1 Apartments 69.5 29.6 % 9 Hotel 12.5 5.3 % 1 Industrial 95.6 40.7 % 3 Office 26.0 11.1 % 1 Retail 19.7 8.4 % 2 Total $ 234.9 100.0 % 17 December 31, 2023 (in millions) Cost Composition Loan Count Apartments $ 76.1 52.6 % 16 Hotel 22.4 15.4 % 4 Industrial 26.0 18.0 % 4 Retail 20.3 14.0 % 4 Total $ 144.8 100.0 % 28 The following table presents our loans by Debt Service Coverage Ratio (“DSCR”): September 30, 2024 (in millions) Cost Loan Count Less than 1.00 $ 10.4 1 1.00 to 1.50 29.5 5 Greater than 1.5 to 2.0 133.5 6 Greater than 2.0 to 3.0 23.8 2 Greater than 3.0 to 4.0 26.1 2 Total $ 223.3 16 DSCR does not include residential mortgage loans. December 31, 2023 (in millions) Cost Loan Count Less than 1.00 $ 36.2 8 1.00 to 1.50 29.4 6 Greater than 1.5 to 2.0 30.9 6 Greater than 2.0 to 3.0 36.0 6 Greater than 3.0 to 4.0 12.3 2 Total $ 144.8 28 The following table presents loans by Loan To Value (“LTV”): September 30, 2024 (in millions) Cost Loan Count Greater than 50.0% to 55.0% $ 83.3 3 Greater than 55.0% to 60.0% 11.8 2 Greater than 60.0% to 70.0% 52.0 3 Greater than 70.0% 87.8 9 Total $ 234.9 17 December 31, 2023 (in millions) Cost Loan Count Equal to or less than 50.0% $ 12.3 2 Greater than 50.0% to 55.0% 9.1 2 Greater than 55.0% to 60.0% 18.9 4 Greater than 60.0% to 70.0% 37.3 6 Greater than 70.0% 67.2 14 Total $ 144.8 28 The following table presents loans by maturity: September 30, 2024 (in millions) Cost Loan Count One Year or Less $ 34.9 3 Greater than One Year and Less than Three 128.1 5 Greater than Three Years and Less than Five Years 19.0 4 Greater than Five Years and Less than Seven Years — — Greater than Seven Years and Less than Ten Years 52.9 5 Total $ 234.9 17 December 31, 2023 (in millions) Cost Loan Count One Year or Less $ 19.7 4 Greater than One Year and Less than Three 34.9 6 Greater than Three Years and Less than Five Years 32.4 6 Greater than Five Years and Less than Seven Years 17.2 4 Greater than Seven Years and Less than Ten Years 40.6 8 Total $ 144.8 28 Investment and Other Gains and Losses The following table presents our gross realized investment gains and losses: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Realized gains on fixed maturities and other: Fixed maturities $ 0.8 $ — $ 8.3 $ 0.6 Other investments, including short-term investments 0.5 2.9 4.2 13.1 Total realized gains on fixed maturities and other 1.3 2.9 12.5 13.7 Realized losses on fixed maturities and other: Fixed maturities (0.6) (1.4) (1.2) (25.1) Other investments, including short-term investments — (4.1) (5.0) (10.9) Total realized losses on fixed maturities and other (0.6) (5.5) (6.2) (36.0) Other net losses recognized on fixed maturities and other: Credit losses on fixed maturities (0.9) (2.0) (1.4) (5.0) Other (0.9) (3.2) (3.2) (6.7) Total other net losses recognized on fixed maturities and other (1.8) (5.2) (4.6) (11.7) Equity securities: Net realized gains (losses) on equity securities 0.5 9.2 — 6.9 Change in unrealized gains (losses) on equity securities held at the end of the period 0.4 (6.1) 29.1 6.1 Net gains (losses) on equity securities 0.9 3.1 29.1 13.0 Net investment and other gains (losses) before income taxes (0.2) (4.7) 30.8 (21.0) Income tax (benefit) provision (0.1) (0.5) 6.5 (5.8) Net investment and other gains (losses), net of income taxes $ (0.1) $ (4.2) $ 24.3 $ (15.2) The cost of securities sold is based on the specific identification method. Changes in unrealized gains (losses) related to fixed maturity investments are summarized as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Change in unrealized gains (losses) Fixed maturities $ 52.0 $ (19.5) $ 21.0 $ 26.9 Other and short-term investments 0.5 0.3 (0.1) (0.2) Net unrealized investment gains (losses) before income taxes 52.5 (19.2) 20.9 26.7 Income tax provision (benefit) 11.2 (3.7) 4.4 4.7 Net unrealized investment gains (losses), net of income taxes $ 41.3 $ (15.5) $ 16.5 $ 22.0 Foreign Currency Exchange Forward Contracts We entered into foreign currency exchange forward contracts primarily to manage currency exposure from our non-USD insurance operations. The currency forward contracts were carried at fair value in our Condensed Consolidated Balance Sheets in Other liabilities and Other assets at September 30, 2024 and December 31, 2023, respectively. The net realized gains and (losses) are included in Net realized investment and other gains (losses) in our Condensed Consolidated Statements of Income (Loss). The fair value of our foreign currency exchange forward contracts as of September 30, 2024 and December 31, 2023 was as follows: As of September 30, 2024 December 31, 2023 (in millions) Notional Amount Fair Value Notional Amount Fair Value Operational currency Open contracts in a gain position $ — $ — $ 75.4 $ 1.8 Open contracts in a loss position — — 43.3 (0.3) Net open contracts for operational currency $ — $ 1.5 Asset manager investment exposure Open contracts in a loss position $ 78.3 (1.7) $ 45.8 $ (0.2) Net open contracts for asset manager investment exposure (1.7) (0.2) Total $ (1.7) $ 1.3 The following table presents our gross realized investment gains and losses on our foreign currency exchange forward contracts: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Realized gains Operational currency exposure $ — $ 0.7 $ 2.8 $ 9.6 Asset manager investment exposure — 1.6 0.2 1.5 Gross realized investment gains — 2.3 3.0 11.1 Realized losses Operational currency exposure — (3.8) (3.6) (10.6) Asset manager investment exposure (1.7) — (1.7) — Gross realized investment losses (1.7) (3.8) (5.3) (10.6) Net realized investment (losses) gains on foreign currency exchange forward contracts $ (1.7) $ (1.5) $ (2.3) $ 0.5 Regulatory Deposits, Pledged Securities and Letters of Credit We are required to maintain assets on deposit with various regulatory authorities to support our insurance and reinsurance operations. We maintain assets pledged as collateral in support of irrevocable letters of credit issued under the terms of certain reinsurance agreements for loss and loss expense reserves. The following table presents our components of restricted investments: As of (in millions) September 30, 2024 December 31, 2023 Securities and cash on deposit for regulatory and other purposes $ 173.3 $ 153.4 Securities and cash pledged as collateral for letters of credit 40.0 109.2 Total restricted investments $ 213.3 $ 262.6 Fair Value Measurements Fair value is the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability, or in the absence of a principal market, the most advantageous market. Market participants are buyers and sellers in the principal (or most advantageous) market that are independent, knowledgeable, able to transact for the asset or liability and willing to transfer the asset or liability. Valuation techniques consistent with the market approach, income approach and/or cost approach are used to measure fair value. The inputs of these valuation techniques are categorized into three levels. • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that can be accessed at the reporting date. We define actively traded as a security that has traded in the past seven days. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. We receive one quote per instrument for Level 2 inputs. • Level 3 inputs are unobservable inputs. Unobservable inputs reflect our own judgments about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances. Significant increases (decreases) in those inputs in isolation could result in a significantly lower (higher) fair value measurement. To validate the fair value of investments in the Company’s Condensed Consolidated Financial Statements, we receive prices from multiple sources including third-party pricing services and our outside investment managers. Through a comparative analysis, the Company validates the reasonableness of its valuations. These prices are determined using observable market information such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of September 30, 2024 and December 31, 2023. A description of the valuation techniques we use to measure assets at fair value is as follows: Fixed Maturities (Available-for-Sale) Levels 1 and 2: • United States Treasury securities are typically valued using Level 1 inputs. For these securities, we obtain fair value measurements from third-party pricing services using quoted prices (unadjusted) in active markets at the reporting date. • United States Government agencies, non-U.S. Government securities, obligations of states and political subdivisions, credit securities and foreign denominated government and credit securities are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, yield curves, live trading levels, trade execution data, credit information and the security’s terms and conditions, among other things. • Asset and mortgage-backed securities and collateralized loan obligations are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. Fixed Maturities (Available-for-Sale) Level 3: We own term loans and asset-back securities that are valued using unobservable inputs. Equity Securities Level 1: For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Equity Securities Level 3: We own certain equity securities that are reported at fair value using Level 3 inputs. The valuation techniques for these securities include the following: • Fair value measurements for an investment in an equity fund obtained by applying final prices provided by the administrator of the fund, which is based upon certain estimates and assumptions. • Fair value measurements from brokers and independent valuation services, both based upon estimates, assumptions and other unobservable inputs. Short-term Investments: Short-term investments are principally reported at fair value using Level 1 inputs, with the exception of short-term corporate and governmental bonds reported at fair value using Level 2 inputs as described in the fixed maturities section above. Values for the investments categorized as Level 1 are obtained from various financial institutions as of the reporting date. Other investments: Other investments include private securities for which we have elected the fair value option of accounting, and are valued using unobservable Level 3 inputs. Derivative assets: As a result of the Company’s commutation of the assumed reinsurance agreement with Riverstone Holdings Limited, the Company classified the ceded reserves on the Malta business as a derivative in accordance with ASC 815. As the ceded reserves are shorter term in nature, management has concluded that the fair value is equivalent to its carrying value, resulting in no impact to earnings. Derivative liabilities: We enter into foreign currency forward contracts to hedge our investment exposure to foreign currencies. These derivatives are carried at fair value using Level 2 inputs, primarily observable foreign exchange rates at the end of the period. Based on an analysis of the inputs, our financial assets and liabilities measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) September 30, Level 1 (1) Level 2 (2) Level 3 (3) Fixed maturities U.S. Governments $ 264.9 $ 262.7 $ 2.2 $ — Foreign Governments 7.4 — 7.4 — Obligations of states and political subdivisions 85.2 — 85.2 — Corporate bonds 1,244.7 — 1,222.0 22.7 Commercial mortgage-backed securities 291.7 — 291.7 — Residential mortgage-backed securities 218.6 — 218.6 — Asset-backed securities 108.4 — 94.7 13.7 Collateralized loan obligations 147.3 — 147.3 — Total fixed maturities 2,368.2 262.7 2,069.1 36.4 Equity securities 85.3 3.4 — 81.9 Other investments 37.7 — — 37.7 Short-term investments 590.5 590.5 — — Derivatives 21.5 — 21.5 — Total assets $ 3,103.2 $ 856.6 $ 2,090.6 $ 156.0 Derivatives 1.7 — 1.7 — Total liabilities $ 1.7 $ — $ 1.7 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, Level 1 (1) Level 2 (2) Level 3 (3) Fixed maturities U.S. Governments $ 362.2 $ 360.1 $ 2.1 $ — Foreign Governments 30.3 — 30.3 — Obligations of states and political subdivisions 94.4 — 94.4 — Corporate bonds 1,213.1 — 1,180.5 32.6 Commercial mortgage-backed securities 280.5 — 280.5 — Residential mortgage-backed securities 248.8 — 248.8 — Asset-backed securities 142.0 — 124.2 17.8 Collateralized loan obligations 214.1 — 214.1 — Total fixed maturities 2,585.4 360.1 2,174.9 50.4 Equity securities 10.7 4.3 — 6.4 Other investments 0.2 — 0.2 — Short-term investments 429.5 429.0 0.5 — Derivatives 1.3 — 1.3 — Total assets $ 3,027.1 $ 793.4 $ 2,176.9 $ 56.8 (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs The fair value measurements in the tables above do not equal Total investments on our Condensed Consolidated Balance Sheets as they primarily exclude Mortgage loans , Private loans , certain Other investments and Short-term investments . Our mortgage loans and private loans, some of which are classified as short-term investments based on the time to maturity at acquisition, are carried at amortized cost. Certain other investments are accounted for in accordance with the equity-method of accounting, carried at amortized cost or use NAV as a practical expedient. A reconciliation of the beginning and ending balances for the investments categorized as Level 3 are as follows: Fair Value Measurements Using Unobservable Inputs (Level 3) (in millions) Fixed Maturities Equity Other Investments Total Beginning balance, January 1, 2024 $ 50.4 $ 6.4 $ — $ 56.8 Transfers into Level 3 0.7 — — 0.7 Transfers out of Level 3 (10.1) — — (10.1) Total gains or losses (realized/unrealized): Included in net income 1.2 28.3 — 29.5 Included in other comprehensive income — — — — Purchases, issuances, sales, and settlements: Purchases 1.9 47.2 49.8 98.9 Sales — — — — Settlements (7.7) — (12.1) (19.8) Ending balance, September 30, 2024 $ 36.4 $ 81.9 $ 37.7 $ 156.0 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at September 30, 2024 $ — $ 29.3 $ — $ 29.3 (in millions) Fixed Maturities Equity Total Beginning balance, January 1, 2023 $ 40.7 $ 15.5 $ 56.2 Transfers into Level 3 5.6 — 5.6 Transfers out of Level 3 (5.6) (7.6) (13.2) Total gains or losses (realized/unrealized): Included in net income (0.1) (0.4) (0.5) Included in other comprehensive loss 0.8 — 0.8 Purchases, issuances, sales, and settlements: Purchases 10.6 — 10.6 Sales (0.5) (1.1) (1.6) Settlements (1.1) — (1.1) Ending balance, December 31, 2023 $ 50.4 $ 6.4 $ 56.8 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2023 $ — $ (0.8) $ (0.8) At September 30, 2024 and December 31, 2023, we did not have any financial assets or financial liabilities measured at fair value on a nonrecurring basis. The Company holds certain investments at cost, less an allowance for expected credit losses, on the Condensed Consolidated Balance Sheets. The fair value of the Company’s investments is estimated using a discounted cash flow analysis. Due to the level of unobservable inputs factored into the estimation of fair value, the valuation would be categorized as Level 3. The cost and estimated fair value of these investments were: As of September 30, 2024 December 31, 2023 (in millions) Cost Fair Value Cost Fair Value Mortgage loans $ 234.9 $ 240.3 $ 144.8 $ 148.8 Private loans 200.7 201.8 — — Total $ 435.6 $ 442.1 $ 144.8 $ 148.8

Allowance for Credit Losses

Allowance for Credit Losses	9 Months Ended
	Sep. 30, 2024
Credit Loss [Abstract]
Allowance for Credit Losses	Allowance for Credit Losses Premiums receivable The following table presents the balances of premiums receivable, net of allowance for estimated uncollectible premiums, including expected lifetime credit losses and the changes in the allowance for the respective periods: (in millions) Premiums Receivable, Net of Allowance for Estimated Uncollectible Premiums Allowance for Estimated Uncollectible Premiums Successor Balance, December 31, 2023 $ 230.7 $ 3.0 Current period change for estimated uncollectible premiums 3.0 Write-offs of uncollectible premiums receivable (1.8) Balance, September 30, 2024 $ 191.7 $ 4.2 Predecessor Balance, December 31, 2022 $ 292.0 $ 4.7 Current period change for estimated uncollectible premiums 5.1 Write-offs of uncollectible premiums receivable (2.4) Balance, September 30, 2023 $ 269.7 $ 7.4 Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, including expected credit losses and changes in the allowance for the respective periods: (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Successor Balance, December 31, 2023 $ 2,959.3 $ — Balance, September 30, 2024 $ 3,130.7 $ — Predecessor Balance, December 31, 2022 $ 3,029.1 $ 4.7 Balance, September 30, 2023 $ 2,889.6 $ 4.7 We primarily utilize A.M. Best credit ratings when determining the allowance and adjust as needed based on our historical experience with the reinsurers. A portion of our reinsurance recoverables are collateralized by letters of credit, funds held or trust agreements.

Reserves for Losses and Loss Ad

Reserves for Losses and Loss Adjustment Expenses	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Reserves for Losses and Loss Adjustment Expenses	Reserves for Losses and Loss Adjustment Expenses The following table provides a reconciliation of reserves for losses and loss adjustment expenses (“LAE”): Successor Predecessor (in millions) Nine Months Ended Nine Months Ended Net reserves - beginning of the year $ 2,747.1 $ 2,213.1 Add: Losses and LAE incurred during current calendar year, net of reinsurance: Current accident year 583.8 680.9 Prior accident years 209.7 126.0 Losses and LAE incurred during calendar year, net of reinsurance 793.5 806.9 Deduct: Losses and LAE payments made during current calendar year, net of reinsurance: Current accident year 53.2 94.9 Prior accident years 552.6 361.6 Losses and LAE payments made during current calendar year, net of reinsurance: 605.8 456.5 Add/(Deduct): Divestitures (1) — 24.4 Retroactive reinsurance (2) — 21.7 Deferred gain on U.S. loss portfolio transfer, net of amortization — (16.8) Purchase accounting adjustment (3) 19.4 — Total net reserve adjustments 19.4 29.3 Foreign exchange adjustments (1.6) 0.9 Net reserves - end of period 2,952.6 2,593.7 Add: Reinsurance recoverables on unpaid losses and LAE, end of period 2,840.3 2,735.0 Gross reserves - end of period $ 5,792.9 $ 5,328.7 (1) For the nine months ended September 30, 2023, the adjustment relates to the year-to-date activity of Syndicate 1200 and on reinsurance contracts with AUA subsidiaries. Refer to the sale of Argo Underwriting Agency Limited in Note 1, “Business and Significant Accounting Policies” for additional information. (2) In connection with the sale of AUA, the Company entered into two retroactive reinsurance agreements with AUA subsidiaries. (3) Impact of measurement period adjustment in connection with the Merger. R efer to Note 1, “Business and Significant Accounting Policies” for additional information. Reserves for losses and LAE represent the estimated indemnity cost and related adjustment expenses necessary to investigate and settle claims. Such estimates are based upon individual case estimates for reported claims, estimates from ceding companies for reinsurance assumed and actuarial estimates for losses that have been incurred but not yet reported to the insurer. Any change in probable ultimate liabilities is reflected in current operating results. The impact from the unfavorable (favorable) development of prior accident years’ loss and LAE reserves on each reporting segment is presented below: Successor Predecessor (in millions) Nine Months Ended Nine Months Ended U.S. Operations $ 125.1 $ 111.7 International Operations 77.3 11.7 Run-off Lines 7.3 2.6 Total unfavorable (favorable) prior-year development $ 209.7 $ 126.0 The following describes the primary factors behind each segment’s net prior accident year loss reserve development for the nine months ended September 30, 2024 and 2023: Nine months ended September 30, 2024: • U.S. Operations: Net unfavorable development primarily related to the recognition of higher-than-expected loss experience across a number of specialty, casualty, and professional lines and by updates to the expectations for future loss experience and development, along with movements on large individual surety claims in specialty lines. • International Operations : Net unfavorable development primarily related to the recognition of higher-than-expected loss experience in Bermuda professional and casualty lines and by updates to the expectations for future loss experience and development. • Run-off Lines: Net unfavorable loss reserve development on prior accident years in other run-off lines. Nine months ended September 30, 2023: • U.S. Operations: Net unfavorable development primarily related to liability and professional lines partially offset by favorable development in specialty lines. The liability lines development was driven by actual losses greater than expected including the impact of large claims with a significant portion of the unfavorable development coming from businesses we have exited. The professional lines development was driven by movements on individual management liability claims. The favorable development in specialty lines was due to a lack of claim activity in surety business. • International Operations : Net unfavorable development primarily related to movements on claims in professional and liability lines in our Bermuda operations partially offset by favorable development in runoff Reinsurance lines. • Run-off Lines: Net unfavorable loss reserve development on prior accident years in other run-off lines. Our reserves represent the best estimate of our ultimate liabilities, based on currently known facts, current law, current technology and reasonable assumptions where facts are not known. Due to the significant uncertainties and related management judgments, there can be no assurance that future favorable or unfavorable loss development, which may be material, will not occur.

Disclosures About Fair Value of

Disclosures About Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Disclosures about Fair Value of Financial Instruments	Disclosures About Fair Value of Financial Instruments Cash. The carrying amount approximates fair value. Investment securities, mortgage loan and private loan investments, and short-term investments. See Note 3, “Investments,” for additional information. Premiums receivable and reinsurance recoverables on paid losses. The carrying value of current receivables and reinsurance recoverables on paid losses approximates fair value due to short-term nature. Debt. At September 30, 2024 and December 31, 2023, the fair value of our debt instruments is determined using both Level 1 and Level 2 inputs, as previously defined in Note 3, “Investments.” We receive fair value prices for similar financial instruments being traded in active markets. These prices are determined using observable market information such as publicly traded quoted prices, and trading prices for similar financial instruments actively being traded in the current market. We have reviewed the processes used by third-party providers for pricing these instruments and have determined that they result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of September 30, 2024 and December 31, 2023. A description of the valuation techniques we use to measure these liabilities at fair value is as follows: Senior Unsecured Fixed Rate Notes Level 1: • Our senior unsecured fixed rate notes are valued using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Junior Subordinated Debentures Level 2: • Our trust preferred debentures and subordinated debentures are typically valued using Level 2 inputs. For these securities, we obtain fair value measurements using quoted prices for similar securities being traded in active markets at the reporting date, as our specific debt instruments are less frequently traded. A summary of our financial instruments whose carrying value did not equal fair value is shown below: September 30, 2024 December 31, 2023 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 161.7 $ 172.7 $ 160.8 $ 165.9 Subordinated debentures 81.0 84.9 80.4 83.3 Total junior subordinated debentures 242.7 257.6 241.2 249.2 Senior unsecured fixed rate notes 128.7 130.4 128.0 132.7 $ 371.4 $ 388.0 $ 369.2 $ 381.9 Based on an analysis of the inputs, our financial instruments measured at fair value for disclosure purposes have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) September 30, 2024 Level 1 (1) Level 2 (2) Level 3 (3) Junior subordinated debentures: Trust preferred debentures $ 172.7 $ — $ 172.7 $ — Subordinated debentures 84.9 — 84.9 — Total junior subordinated debentures 257.6 — 257.6 — Senior unsecured fixed rate notes 130.4 130.4 — — $ 388.0 $ 130.4 $ 257.6 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, 2023 Level 1 (1) Level 2 (2) Level 3 (3) Junior subordinated debentures: Trust preferred debentures $ 165.9 $ — $ 165.9 $ — Subordinated debentures 83.3 — 83.3 — Total junior subordinated debentures 249.2 — 249.2 — Senior unsecured fixed rate notes 132.7 132.7 — — $ 381.9 $ 132.7 $ 249.2 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock As a result of the Merger, the Company’s authorized and outstanding share capital is owned by BNRE Triangle Acquisition Inc., a subsidiary of Brookfield Wealth Solutions Ltd. For the six months ended June 30, 2024, the Company issued a total of 200.0 million shares of its common stock at par value for $200.0 million to BNRE Triangle Acquisition Inc. Preferred Stock Dividend On August 16, 2024, our Board of Directors declared a quarterly cash dividend in the amount of $437.50 per share on our 7.00% Resettable Fixed Rate Preferred Stock, Series A, par value of $1.00 per share, with a liquidation preference of $25,000 per share (the “Series A Preferred Stock”). Holders of depositary shares, each representing a 1/1,000th interest in a share of Series A Preferred Stock (the “Depositary Shares”), received $0.43750 per Depositary Share. On September 16, 2024, we paid $2.6 million to our stockholders of record, as of August 31, 2024, of the Series A Preferred Stock. Merger with AGIH Merger Sub, Inc. On September 25, 2024, the Company and Merger Sub entered into an Agreement and Plan of Merger, pursuant to which, among other things, Merger Sub merged with and into the Company, reducing the number of authorized shares of the Company’s common stock and preferred stock. Additionally, the Merger with AGIH Merger Sub, Inc. reduced the par value of the Company’s common stock. Refer to the Merger with AGIH Merger Sub, Inc. in Note 1, “Business and Significant Accounting Policies” for additional information.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) A summary of changes in accumulated other comprehensive income (loss), net of taxes (where applicable) by component for the nine months ended September 30, 2024 and 2023 is presented below: (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2024 $ 0.1 $ 51.1 $ 0.6 $ 51.8 Other comprehensive income (loss) before reclassifications 0.3 20.3 — 20.6 Amounts reclassified from accumulated other comprehensive income — (3.8) — (3.8) Net current-period other comprehensive income (loss) 0.3 16.5 — 16.8 Balance, September 30, 2024 $ 0.4 $ 67.6 $ 0.6 $ 68.6 (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2023 $ (4.2) $ (293.1) $ (7.8) $ (305.1) Other comprehensive income (loss) before reclassifications 1.0 (0.4) 0.8 1.4 Amounts reclassified from accumulated other comprehensive loss — 22.4 — 22.4 Net current-period other comprehensive income (loss) 1.0 22.0 0.8 23.8 Balance, September 30, 2023 $ (3.2) $ (271.1) $ (7.0) $ (281.3) The amounts reclassified from accumulated other comprehensive income (loss) shown in the above table have been included in the following captions in our Condensed Consolidated Statements of Income (Loss): Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Unrealized gains and losses on securities: Net realized investment and other gains (losses) $ (1.6) $ (1.5) $ 4.8 $ (27.4) Income tax provision (benefit) 0.3 (0.4) (1.0) 5.0 Total, net of taxes $ (1.3) $ (1.9) $ 3.8 $ (22.4) Income tax effects are released from accumulated other comprehensive income (loss) for unrealized gains or losses when the gains or losses are realized and are taxed at the statutory rate based on jurisdiction of the underlying transaction.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2024
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Interest paid and income taxes paid (recovered) were as follows: Successor Predecessor (in millions) Nine Months Ended Nine Months Ended Senior unsecured fixed rate notes $ 7.0 $ 7.0 Junior subordinated debentures 18.6 17.2 Other indebtedness 1.9 0.8 Total interest paid $ 27.5 $ 25.0 Income taxes paid $ 0.1 $ 0.2 Income taxes recovered (31.3) (0.1) Income taxes paid (recovered), net $ (31.2) $ 0.1 Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2024 excludes $3.3 million of noncash activity for a lease which commenced in 2024. The lease is reflected on our Condensed Consolidated Balance Sheets in Operating lease right-of-use assets and Operating lease liabilities.

Underwriting, Acquisition and G

Underwriting, Acquisition and General Expenses	9 Months Ended
	Sep. 30, 2024
Underwriting, Acquisition and Insurance Expenses [Abstract]
Underwriting, Acquisition and General Expenses	Underwriting, Acquisition and General Expenses Underwriting, acquisition and general expenses were as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Commission expense $ 7.6 $ 46.6 $ 65.2 $ 144.5 Other underwriting and insurance expenses 62.6 74.0 195.0 230.2 Amortization of value of business acquired and other intangible assets 43.0 — 129.1 — Total 113.2 120.6 389.3 374.7 Net deferral of policy acquisition costs (2.3) (4.5) (44.5) (10.7) Total underwriting, acquisition and general expenses $ 110.9 $ 116.1 $ 344.8 $ 364.0

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company was incorporated under the laws of Bermuda until November 30, 2023. Under Bermuda law, the Company was not obligated to pay any tax in Bermuda based upon income or capital gains. We previously received an undertaking from the Supervisor of Insurance in Bermuda pursuant to the provisions of the Exempted Undertakings Tax Protection Act, 2011 which exempted us from any Bermuda taxes computed on profits, income or any capital asset, gain or appreciation or any tax in the nature of estate, duty or inheritance tax, at least until the year 2035. As of November 30, 2023, the Company redomiciled from Bermuda to the United States. In connection with redomiciling from Bermuda to the United States, the Company’s predecessor pre-tax loss and tax benefit is reported in Bermuda. Subsequent to redomiciling, the Company’s successor pre-tax income and tax provision is reported in the U.S. Separately, Argo Re has submitted an Internal Revenue Code Section 953(d) election to treat the entity as a U.S. taxpayer. The election is deemed retroactive to the period beginning January 1, 2023. Argo Re pre-tax loss for the predecessor period is reported in Bermuda. The retroactive U.S. tax benefit incurred for the predecessor period is reflected in purchase accounting. Argo Re pre-tax income and tax provision is reported in the United States for the successor period. On February 2, 2023, Argo International Holdings Limited, a wholly-owned U.K. subsidiary of the Company, sold AUA. See Note 1, “Business and Significant Accounting Policies” for additional information related to this transaction. The predecessor period includes activity of AUA until it was sold. Subsequent to the AUA sale, the Company retained one U.K. subsidiary that is subject to the tax laws of that country. Under current law, the subsidiary is taxed at the applicable corporate tax rates and files a separate U.K. income tax return. We have subsidiaries based in the U.S. that are subject to U.S. tax laws. Under current law, these subsidiaries are taxed at the applicable corporate tax rates. Beginning January 1, 2024, our U.S. subsidiaries file a consolidated U.S. federal income tax return with BAMR US Holdings LLC, a subsidiary of Brookfield Wealth Solutions Ltd. We also have operations in Ireland and Italy which are subject to income taxes imposed by the jurisdiction in which they operate. Furthermore, we have an operation in Barbados which is not subject to income tax under the laws of that country. On August 16, 2022, U.S. legislation referred to as the Inflation Reduction Act of 2022 was enacted. This legislation enacted a new Corporate Alternative Minimum Tax (“CAMT”) and Excise Tax on Repurchases of Corporate Stock. The Company has determined as of the period ended September 30, 2024, that it is subject to CAMT. The recognition of applicable CAMT is reported on a consolidated basis with Brookfield Wealth Solutions Ltd. The Company is not subject to Excise Tax on Repurchases of Corporate Stock. Our expected income tax provision computed on pre-tax income (loss) at the weighted average tax rate has been calculated as the sum of the pre-tax income (loss) in each jurisdiction multiplied by that jurisdiction’s applicable statutory tax rate. For the three and nine months ended September 30, 2024 and 2023, pre-tax income (loss) attributable to our operations and the corresponding operations’ effective tax rates were as follows: Successor Predecessor Three Months Ended Three Months Ended (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ — — % $ (9.8) — % United States (163.9) 21.0 % (18.1) (95.5) % United Kingdom (2.1) — % (1.6) (22.5) % Barbados — — % — (1) — % Ireland — — % — (1) — % Italy (0.7) — % 0.2 20.0 % Pre-tax income (loss) $ (166.7) 20.6 % $ (29.3) (60.1) % (1) Pre-tax income (loss) for the respective year was less than $0.1 million. Successor Predecessor Nine Months Ended Nine Months Ended (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ — — % $ (21.1) — % United States (114.1) 23.9 % (31.2) (32.9) % United Kingdom (4.4) — % (23.2) 30.4 % Barbados — — % — (1) — % United Arab Emirates — — % 0.3 — % Ireland — — % (0.1) — % Italy (2.7) (1.4) % 0.1 50.3 % Pre-tax income (loss) $ (121.2) 22.5 % $ (75.2) (4.4) % (1) Pre-tax income (loss) for the respective year was less than $0.1 million. A reconciliation of the difference between the provision (benefit) for income taxes and the expected tax provision (benefit) at the weighted average tax rate is as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Income tax provision (benefit) at expected rate $ (35.1) $ (4.1) $ (25.7) $ (11.0) Tax effect of: Nontaxable investment income — — (0.2) (0.1) Foreign exchange adjustments — — — (2.6) Base Erosion and Anti-Abuse Tax — 20.4 — 16.9 Withholding taxes — — — 0.1 Ireland Capital Loss — — 3.3 — U.S. state tax expense, net of federal income tax effect — — — (1.2) Change in uncertain tax position liability — 0.2 — 1.2 Change in valuation allowance 0.3 — (2.2) 0.1 Impact of change in tax rate related to Finance Act 2021 — — — (0.4) Prior period adjustment (0.3) 0.2 (3.6) 0.1 Other 0.7 0.9 1.2 0.2 Income tax provision (benefit) $ (34.4) $ 17.6 $ (27.2) $ 3.3 Our gross deferred tax assets are supported by taxes paid in previous periods, reversal of taxable temporary differences and recognition of future taxable income. Management regularly evaluates the recoverability of the deferred tax assets and makes any necessary adjustments to them based upon any changes in management’s expectations of future taxable income. Realization of deferred tax assets is dependent upon our generation of future taxable income sufficient to recover tax benefits that cannot be recovered from taxes paid in the carryback period, generally for our U.S. property and casualty insurers two years for net operating losses and for all our U.S. subsidiaries three years for capital losses. If a company determines that any of its deferred tax assets will not result in future tax benefits, a valuation allowance must be established for the portion of these assets that are not expected to be realized. For three and nine months ended September 30, 2024, the net change in valuation allowance for deferred tax assets was an increase of $0.3 million and decrease of $2.2 million, respectively. For the three months ended September 30, 2024, the change in valuation allowance related to the limited net operating loss carryforwards incurred in the United Kingdom. For the nine months ended September 30, 2024, the change in valuation allowance primarily related to the following: $3.3 million decrease related to an Ireland Capital Loss due to dissolution and a $1.1 million increase related to limited net operating loss carryforwards incurred in the United Kingdom. Based upon a review of our available evidence, both positive and negative discussed above, the Company concluded that it is more-likely-than-not that $65.9 million of our deferred tax assets will be realized. For any uncertain tax positions not meeting the “more-likely-than-not” recognition threshold, accounting standards require recognition, measurement and disclosure in the Company’s Condensed Consolidated Financial Statements. No change to the uncertain tax positions were recorded for federal or state income tax liability for the three and nine months ended September 30, 2024. A net decrease of interest in the amount of $1.1 million has been recorded in the line item Interest expense in our Condensed Consolidated Statements of Income (Loss) for the nine months ended September 30, 2024. A net decrease of penalty in the amount of $0.2 million has been recorded in the line item Underwriting, acquisition, and general expenses in our Consolidated Statements of Income (Loss) for the nine months ended September 30, 2024. The Company did not incur interest and penalty for the three months ended September 30, 2024.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Actions Argo Group’s subsidiaries are parties to legal actions incidental to their business. As of September 30, 2024, management believes that the resolution of these matters would not materially affect our financial condition or results of operations. Federal Securities Class Action The Police & Fire Retirement System City of Detroit v. Argo Group International Holdings, Inc., et al., No. 22-cv-8971 (S.D.N.Y.) On October 20, 2022, a securities class action lawsuit was filed in the United States District Court for the Southern District of New York against the Company and certain of its current and former officers, alleging securities fraud violations under sections 10(b) and 20(a) of the Securities Exchange Act of 1934. Plaintiff alleges that from February 13, 2018 through August 9, 2022, the defendants made false and misleading statements concerning the Company’s reserves and underwriting standards. On January 18, 2023, U.S. District Judge Lewis A. Kaplan granted the Police and Fire Retirement System City of Detroit and the Oklahoma Law Enforcement Retirement System’s joint motion for appointment as lead plaintiff. On March 27, 2023, lead plaintiffs filed an amended class action complaint. On May 26, 2023, the defendants moved to dismiss the amended class action complaint. On July 13, 2023, lead plaintiffs filed an opposition to such motion, after which defendants filed a reply on August 14, 2023. Bermuda Appraisal Petitions In April 2023, appraisal petitions were filed in the Supreme Court of Bermuda (the “Court”) relating to the acquisition of the Company by Brookfield Wealth Solutions Ltd. for $30.00 per share (the “Transaction Price”) that closed on November 16, 2023. The petitions were filed by certain stockholders pursuant to Section 106(6) of the Bermuda Companies Act 1981 and are captioned Corbin Erisa Opportunity Fund, Ltd. v. Argo Group International Holdings, Ltd., Corbin Opportunity Fund, L.P. v. Argo Group International Holdings, Ltd., Fourworld Event Opportunities, LP v. Argo Group International Holdings, Ltd., Fourworld Global Opportunities Fund, Ltd. v. Argo Group International Holdings, Ltd., Fourworld Special Opportunities Fund, LLC v. Argo Group International Holdings, Ltd., and FW Deep Value Opportunities Fund I, LLC v. Argo Group International Holdings, Ltd. Section 106(6) permits a stockholder of a Bermuda corporation, such as the Company, to petition the Court for a determination of the fair value of the Company’s shares if they are not satisfied with the Transaction Price. On January 3, 2024, the Company filed a summons to stay the appraisal action pending judgment of the Judicial Committee of the Privy Council in the matter captioned “In re matter of Jardine Strategy Holdings Limited Case No: Civ/2022/14-31.” Hearings were held on July 9, 2024 and July 18, 2024. The Court is considering the stay application and will issue a decision in due course. The Company intends to continue to defend this matter vigorously. Contractual Commitments We have contractual commitments to invest up to $82.2 million related to our limited partnership investments at September 30, 2024, as further disclosed in Note 3, “Investments.” These commitments will be funded as required by the partnership agreements which can be called to be fulfilled at any time. Additionally, the Company has commitments to fund up to $75.9 million related to various other investments, including term and mortgage loans.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Segment Information	Segment Information We are primarily engaged in underwriting property and casualty insurance. We have two ongoing reporting segments: U.S. Operations and International Operations. Additionally, we have Run-off Lines for certain products that we no longer underwrite. We consider many factors, including the nature of each segment’s insurance and reinsurance products, production sources, distribution strategies and the regulatory environment, in determining how to aggregate reporting segments. In evaluating the operating performance of our segments, we focus on core underwriting and investing results before the consideration of realized gains or losses from investments. Net investment and other gains (losses) are reported as a component of the Corporate and Other segment, as decisions regarding the acquisition and disposal of securities reside with the corporate investment function and are not under the control of the individual business segments. Identifiable assets by segment are those assets used in the operation of each segment. Revenue and income (loss) before income taxes for each segment were as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Revenue: Net earned premiums U.S. Operations $ 210.4 $ 314.1 $ 761.9 $ 950.9 International Operations 23.9 28.5 75.8 111.4 Run-off Lines — 0.1 0.2 0.2 Total net earned premiums 234.3 342.7 837.9 1,062.5 Net investment income U.S. Operations 52.3 33.2 158.4 84.7 International Operations 7.6 6.2 22.8 15.8 Run-off Lines 2.4 1.0 5.9 2.4 Total net investment income 62.3 40.4 187.1 102.9 Net investment and other gains (losses) (0.2) (4.7) 30.8 (21.0) Total revenue $ 296.4 $ 378.4 $ 1,055.8 $ 1,144.4 Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Income (loss) before income taxes U.S. Operations $ (100.3) $ (14.0) $ (74.3) $ (23.2) International Operations (67.1) (2.6) (70.1) 9.3 Run-off Lines (5.7) — (5.1) (1.0) Total segment income (loss) before income taxes (173.1) (16.6) (149.5) (14.9) Corporate and Other 2.8 (11.3) (5.6) (39.2) Net investment and other gains (losses) (0.2) (4.7) 30.8 (21.0) Foreign currency exchange gains (losses) 3.8 3.3 3.1 (0.1) Total income (loss) before income taxes $ (166.7) $ (29.3) $ (121.2) $ (75.2) The table below presents net earned premiums by geographic location for the three and nine months ended September 30, 2024 and 2023. For this disclosure, we determine geographic location by the country of domicile of our subsidiaries that underwrite the business and not by the location of insureds or reinsureds from whom the business was generated. Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended United States $ 210.4 $ 314.2 $ 762.1 $ 951.1 United Kingdom — — — 48.3 Bermuda 23.9 28.5 75.8 63.1 Total earned premiums $ 234.3 $ 342.7 $ 837.9 $ 1,062.5 The following table represents identifiable assets: As of (in millions) September 30, 2024 December 31, 2023 U.S. Operations $ 6,788.6 $ 6,279.0 International Operations 1,705.9 1,888.9 Run-off Lines 215.7 221.4 Corporate and Other 106.4 113.8 Total assets $ 8,816.6 $ 8,503.1

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions As part of the Merger, the Company has entered into recurring transactions and agreements with Brookfield Wealth Solutions Ltd., its subsidiaries and affiliates. For the three and nine months ended September 30, 2024, the Company purchased related party investments of $207.0 million and $459.7 million, respectively. Additionally, for the nine months ended September 30, 2024, the Company recorded a gain of $27.9 million, driven from a related party equity security, which is reflected in Net investment and other gains (losses) on our Condensed Consolidated Statements of Income (Loss). Related party investments as of September 30, 2024 were primarily attributed to $277.2 million of mortgage and private loans and $138.6 million in other investments. Additionally, the Company has unfunded commitments totaling $55.0 million across the related party investments. Investment transactions with related parties are accounted for in the same manner as those with unrelated parties in the financial statements. For the three and nine months ended September 30, 2024, the Company incurred investment management fees due to related party arrangements of $2.6 million and $7.4 million, which is recognized in Net investment income on our Condensed Consolidated Statements of Income (Loss). As of September 30, 2024, the related party investment management fees payable is $2.6 million which is recognized in Accrued underwriting expenses and other liabilities on our Condensed Consolidated Balance Sheets. Additionally, the Company issued common stock to BNRE Triangle Acquisition Inc. See Note 7, “Stockholders’ Equity,” for additional information.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2024
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events There are no subsequent events identified as of the date of this report.

Business and Significant Acco_2

Business and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying Condensed Consolidated Financial Statements of Argo Group International Holdings, Inc. and its subsidiaries (“Argo Group,” “we,” “us,” “our” or the “Company”) have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Argo Group is an underwriter of specialty insurance products in the property and casualty market. On November 16, 2023, we merged with Brookfield Wealth Solutions Ltd. (formerly known as Brookfield Reinsurance Ltd.), which resulted in a change to the Company’s ownership (the “Merger”). Brookfield Wealth Solutions Ltd. elected to push-down its purchase accounting, which resulted in the Company reflecting the fair market value of our assets and liabilities as of November 16, 2023, in accordance with Accounting Standards Codification (“ASC”) 805, Business Combinations. The application of push-down accounting created a new basis of accounting for all of our assets and liabilities. As such, the Company’s financial position, results of operations, and cash flows subsequent to the acquisition are not comparable with those prior to November 16, 2023, and therefore have been separated to indicate pre-acquisition and post-acquisition periods. The pre-acquisition period through November 15, 2023 is referred to as the Predecessor. The post-acquisition period, November 16, 2023 and forward, includes the impact of push-down accounting and is referred to as the Successor. The preparation of interim financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of revenues and expenses during the reporting period. The major estimates reflected in our Condensed Consolidated Financial Statements include, but are not limited to, reserves for losses and loss adjustment expenses; reinsurance recoverables, including the reinsurance recoverables allowance for expected credit losses; fair value of investments and assessment of potential impairment, including the allowance for credit losses on fixed maturity securities; valuation of intangibles, including those identified as part of purchase accounting related to the Merger, and our deferred tax asset valuation allowance. Actual results could materially differ from those estimates. Certain financial information that is normally included in annual Condensed Consolidated Financial Statements, including certain financial statement footnotes, prepared in accordance with GAAP, is not required for interim reporting purposes and has been condensed or omitted. These statements should be read in conjunction with the Condensed Consolidated Financial Statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2023 filed with the Securities and Exchange Commission ("SEC") (the “2023 Form 10-K”).
Reclassification	Certain reclassifications have been made to financial information presented for prior years to conform to the current year’s presentation.
Allowance for Credit Losses	Allowance for Credit Losses For fixed maturities with a decline in fair value below the amortized cost due to credit-related factors, an allowance is established for the difference between the estimated recoverable value and amortized cost with a corresponding charge to Net investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss). The allowance is limited to the difference between amortized cost and fair value. The estimated recoverable value is the present value of cash flows expected to be collected, as determined by management. The difference between fair value and amortized cost that is not associated with credit-related factors is recognized in the Condensed Consolidated Statements of Comprehensive Income (Loss). Accrued interest is excluded from the measurement of the allowance for credit losses. When determining if a credit loss has been incurred, we may consider the historical performance of the security, available market information and security specific considerations such as the priority payment of the security. In addition, inputs used in our analysis include, but are not limited to, credit ratings and downgrades, delinquency rates, missed scheduled interest or principal payments, purchase yields, underlying asset performance, collateral types, modeled default rates, modeled severity rates, call/prepayment rates, expected cash flows, industry concentrations, and potential or filed bankruptcies or restructurings. In cooperation with our investment managers, we evaluate for credit losses each quarter utilizing a bottom up review approach. At the security level, a determination is made as to whether a decline in fair value below the amortized cost basis is due to credit-related or noncredit-related factors. If we determine that all or a portion of a fixed maturity is uncollectible, the uncollectible amortized cost is written off with a corresponding reduction to the allowance for credit losses. If we collect cash flows that were previously written off, the recovery is recognized in Net investment and other gains (losses) . We also consider whether we intend to sell an available-for-sale security or if it is more likely than not that we will be required to sell the security before recovery of its amortized cost. In these instances, a decline in fair value is recognized in Net investment and other gains (losses) in the Condensed Consolidated Statements of Income (Loss) based on the fair value of the security at the time of assessment, resulting in a new cost basis for the security.
Disclosures about Fair Value of Financial Instruments	Disclosures About Fair Value of Financial Instruments Cash. The carrying amount approximates fair value. Investment securities, mortgage loan and private loan investments, and short-term investments. See Note 3, “Investments,” for additional information. Premiums receivable and reinsurance recoverables on paid losses. The carrying value of current receivables and reinsurance recoverables on paid losses approximates fair value due to short-term nature. Debt. At September 30, 2024 and December 31, 2023, the fair value of our debt instruments is determined using both Level 1 and Level 2 inputs, as previously defined in Note 3, “Investments.” We receive fair value prices for similar financial instruments being traded in active markets. These prices are determined using observable market information such as publicly traded quoted prices, and trading prices for similar financial instruments actively being traded in the current market. We have reviewed the processes used by third-party providers for pricing these instruments and have determined that they result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of September 30, 2024 and December 31, 2023. A description of the valuation techniques we use to measure these liabilities at fair value is as follows: Senior Unsecured Fixed Rate Notes Level 1: • Our senior unsecured fixed rate notes are valued using Level 1 inputs. For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Junior Subordinated Debentures Level 2: • Our trust preferred debentures and subordinated debentures are typically valued using Level 2 inputs. For these securities, we obtain fair value measurements using quoted prices for similar securities being traded in active markets at the reporting date, as our specific debt instruments are less frequently traded. A summary of our financial instruments whose carrying value did not equal fair value is shown below: September 30, 2024 December 31, 2023 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 161.7 $ 172.7 $ 160.8 $ 165.9 Subordinated debentures 81.0 84.9 80.4 83.3 Total junior subordinated debentures 242.7 257.6 241.2 249.2 Senior unsecured fixed rate notes 128.7 130.4 128.0 132.7 $ 371.4 $ 388.0 $ 369.2 $ 381.9 Based on an analysis of the inputs, our financial instruments measured at fair value for disclosure purposes have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) September 30, 2024 Level 1 (1) Level 2 (2) Level 3 (3) Junior subordinated debentures: Trust preferred debentures $ 172.7 $ — $ 172.7 $ — Subordinated debentures 84.9 — 84.9 — Total junior subordinated debentures 257.6 — 257.6 — Senior unsecured fixed rate notes 130.4 130.4 — — $ 388.0 $ 130.4 $ 257.6 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, 2023 Level 1 (1) Level 2 (2) Level 3 (3) Junior subordinated debentures: Trust preferred debentures $ 165.9 $ — $ 165.9 $ — Subordinated debentures 83.3 — 83.3 — Total junior subordinated debentures 249.2 — 249.2 — Senior unsecured fixed rate notes 132.7 132.7 — — $ 381.9 $ 132.7 $ 249.2 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs
Fair Value Measurement	Fair Value Measurements Fair value is the price that would be received upon the sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value measurement assumes that the transaction to sell the asset or transfer the liability occurs in the principal market for the asset or liability, or in the absence of a principal market, the most advantageous market. Market participants are buyers and sellers in the principal (or most advantageous) market that are independent, knowledgeable, able to transact for the asset or liability and willing to transfer the asset or liability. Valuation techniques consistent with the market approach, income approach and/or cost approach are used to measure fair value. The inputs of these valuation techniques are categorized into three levels. • Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that can be accessed at the reporting date. We define actively traded as a security that has traded in the past seven days. • Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. We receive one quote per instrument for Level 2 inputs. • Level 3 inputs are unobservable inputs. Unobservable inputs reflect our own judgments about the assumptions market participants would use in pricing the asset or liability based on the best information available in the circumstances. Significant increases (decreases) in those inputs in isolation could result in a significantly lower (higher) fair value measurement. To validate the fair value of investments in the Company’s Condensed Consolidated Financial Statements, we receive prices from multiple sources including third-party pricing services and our outside investment managers. Through a comparative analysis, the Company validates the reasonableness of its valuations. These prices are determined using observable market information such as dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. We have reviewed the processes used by the third-party providers for pricing the securities and have determined that these processes result in fair values consistent with GAAP requirements. In addition, we review these prices for reasonableness, and have not adjusted any prices received from the third-party providers as of September 30, 2024 and December 31, 2023. A description of the valuation techniques we use to measure assets at fair value is as follows: Fixed Maturities (Available-for-Sale) Levels 1 and 2: • United States Treasury securities are typically valued using Level 1 inputs. For these securities, we obtain fair value measurements from third-party pricing services using quoted prices (unadjusted) in active markets at the reporting date. • United States Government agencies, non-U.S. Government securities, obligations of states and political subdivisions, credit securities and foreign denominated government and credit securities are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, yield curves, live trading levels, trade execution data, credit information and the security’s terms and conditions, among other things. • Asset and mortgage-backed securities and collateralized loan obligations are reported at fair value using Level 2 inputs. For these securities, we obtain fair value measurements from third-party pricing services. Observable data may include dealer quotes, market spreads, cash flows, yield curves, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the security’s terms and conditions, among other things. Fixed Maturities (Available-for-Sale) Level 3: We own term loans and asset-back securities that are valued using unobservable inputs. Equity Securities Level 1: For these securities, we obtain fair value measurements from a third-party pricing service using quoted prices (unadjusted) in active markets at the reporting date. Equity Securities Level 3: We own certain equity securities that are reported at fair value using Level 3 inputs. The valuation techniques for these securities include the following: • Fair value measurements for an investment in an equity fund obtained by applying final prices provided by the administrator of the fund, which is based upon certain estimates and assumptions. • Fair value measurements from brokers and independent valuation services, both based upon estimates, assumptions and other unobservable inputs. Short-term Investments: Short-term investments are principally reported at fair value using Level 1 inputs, with the exception of short-term corporate and governmental bonds reported at fair value using Level 2 inputs as described in the fixed maturities section above. Values for the investments categorized as Level 1 are obtained from various financial institutions as of the reporting date. Other investments: Other investments include private securities for which we have elected the fair value option of accounting, and are valued using unobservable Level 3 inputs. Derivative assets: As a result of the Company’s commutation of the assumed reinsurance agreement with Riverstone Holdings Limited, the Company classified the ceded reserves on the Malta business as a derivative in accordance with ASC 815. As the ceded reserves are shorter term in nature, management has concluded that the fair value is equivalent to its carrying value, resulting in no impact to earnings. Derivative liabilities: We enter into foreign currency forward contracts to hedge our investment exposure to foreign currencies. These derivatives are carried at fair value using Level 2 inputs, primarily observable foreign exchange rates at the end of the period.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value of Investments	The amortized cost, gross unrealized gains, gross unrealized losses, allowance for credit losses, and fair value of fixed maturity investments were as follows: September 30, 2024 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 259.8 $ 5.2 $ 0.1 $ — $ 264.9 Foreign Governments 7.1 0.3 — — 7.4 Obligations of states and political subdivisions 82.2 3.0 — — 85.2 Corporate bonds 1,206.7 39.9 0.9 1.0 1,244.7 Commercial mortgage-backed securities 275.1 16.9 0.3 — 291.7 Residential mortgage-backed securities 204.9 13.7 — — 218.6 Asset-backed securities 104.9 3.5 — — 108.4 Collateralized loan obligations 142.9 4.4 — — 147.3 Total fixed maturities $ 2,283.6 $ 86.9 $ 1.3 $ 1.0 $ 2,368.2 December 31, 2023 (in millions) Amortized Gross Gross Allowance for Credit Losses Fair Fixed maturities U.S. Governments $ 357.7 $ 4.5 $ — $ — $ 362.2 Foreign Governments 27.9 2.6 — 0.2 30.3 Obligations of states and political subdivisions 92.4 2.0 — — 94.4 Corporate bonds 1,185.0 28.9 0.8 — 1,213.1 Commercial mortgage-backed securities 270.9 10.1 0.5 — 280.5 Residential mortgage-backed securities 235.2 13.6 — — 248.8 Asset-backed securities 140.4 1.7 0.1 — 142.0 Collateralized loan obligations 212.0 2.1 — — 214.1 Total fixed maturities $ 2,521.5 $ 65.5 $ 1.4 $ 0.2 $ 2,585.4
Schedule of Amortized Cost and Fair Values of Fixed Maturity Investments, by Contractual Maturity	The amortized cost and fair values of fixed maturity investments as of September 30, 2024, by contractual maturity, were as follows: (in millions) Amortized Fair Due in one year or less $ 304.5 $ 306.4 Due after one year through five years 1,039.3 1,067.4 Due after five years through ten years 191.9 206.8 Due after ten years 20.1 21.6 Structured securities 727.8 766.0 Total $ 2,283.6 $ 2,368.2
Schedule of Carrying Value and Unfunded Investment Commitments of Other Invested Assets Portfolio	Details regarding the carrying value and unfunded investment commitments of Other investments as of September 30, 2024 and December 31, 2023 were as follows: September 30, 2024 December 31, 2023 (in millions) Carrying Unfunded Carrying Unfunded Investment type Hedge funds $ 28.7 $ — $ 56.2 $ — Private equity 258.4 82.2 250.3 93.4 Real estate equity investments 101.0 — — — Other 42.2 30.4 4.5 — Total other investments $ 430.3 $ 112.6 $ 311.0 $ 93.4
Schedule of Unrealized Gain (Loss) on Investments	An aging of unrealized losses on our investments in fixed maturities is presented below: September 30, 2024 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities U.S. Governments $ 17.9 $ 0.1 $ — $ — $ 17.9 $ 0.1 Corporate bonds 17.6 0.9 — — 17.6 0.9 Commercial mortgage-backed securities 19.2 0.3 — — 19.2 0.3 Total fixed maturities $ 54.7 $ 1.3 $ — $ — $ 54.7 $ 1.3 December 31, 2023 Less Than One Year One Year or Greater Total (in millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturities Foreign Governments $ 0.1 $ — $ — $ — $ 0.1 $ — Obligations of states and political subdivisions 0.5 — — — 0.5 — Corporate bonds 38.7 0.8 — — 38.7 0.8 Commercial mortgage-backed securities 32.2 0.5 — — 32.2 0.5 Residential mortgage-backed securities 2.9 — — — 2.9 — Asset-backed securities 11.4 0.1 — — 11.4 0.1 Collateralized loan obligations 21.4 — — — 21.4 — Total fixed maturities $ 107.2 $ 1.4 $ — $ — $ 107.2 $ 1.4
Schedule of Debt Securities, Available-for-sale, Allowance for Credit Loss	The following table presents a roll-forward of the changes in allowance for credit losses on available-for-sale fixed maturities by industry category for the three and nine months ended September 30, 2024 and 2023, respectively: Successor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, June 30, 2024 $ — $ — $ 0.5 $ — $ 0.5 Securities for which allowance was not previously recorded — — 0.2 — 0.2 Additional net increases (decreases) in existing allowance — — 0.3 — 0.3 Ending balance, September 30, 2024 $ — $ — $ 1.0 $ — $ 1.0 Predecessor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, June 30, 2023 $ 1.0 $ — $ 1.4 $ 0.1 $ 2.5 Securities for which allowance was not previously recorded — 0.5 1.4 — 1.9 Securities sold during the period — — (0.1) — (0.1) Additional net increases (decreases) in existing allowance 0.1 — — — 0.1 Ending balance, September 30, 2023 $ 1.1 $ 0.5 $ 2.7 $ 0.1 $ 4.4 Successor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2024 $ 0.2 $ — $ — $ — $ 0.2 Securities for which allowance was not previously recorded — — 0.6 — 0.6 Securities sold during the period — — (0.1) — (0.1) Additional net increases (decreases) in existing allowance (0.2) — 0.5 — 0.3 Ending balance, September 30, 2024 $ — $ — $ 1.0 $ — $ 1.0 Predecessor (in millions) Foreign Governments Obligations of states and political subdivisions Corporate bonds Asset backed securities Total Beginning balance, January 1, 2023 $ 0.7 $ 0.4 $ 1.6 $ 0.1 $ 2.8 Securities for which allowance was not previously recorded 0.1 0.5 2.1 — 2.7 Securities sold during the period — — (0.5) — (0.5) Additional net increases (decreases) in existing allowance 0.3 (0.4) (0.5) — (0.6) Ending balance, September 30, 2023 $ 1.1 $ 0.5 $ 2.7 $ 0.1 $ 4.4
Schedule of Accounts, Notes, Loans and Financing Receivable	The following table presents loans by property type: September 30, 2024 (in millions) Cost Composition Loan Count Residential $ 11.6 4.9 % 1 Apartments 69.5 29.6 % 9 Hotel 12.5 5.3 % 1 Industrial 95.6 40.7 % 3 Office 26.0 11.1 % 1 Retail 19.7 8.4 % 2 Total $ 234.9 100.0 % 17 December 31, 2023 (in millions) Cost Composition Loan Count Apartments $ 76.1 52.6 % 16 Hotel 22.4 15.4 % 4 Industrial 26.0 18.0 % 4 Retail 20.3 14.0 % 4 Total $ 144.8 100.0 % 28
Schedule of Financing Receivable Credit Quality Indicators	The following table presents our loans by Debt Service Coverage Ratio (“DSCR”): September 30, 2024 (in millions) Cost Loan Count Less than 1.00 $ 10.4 1 1.00 to 1.50 29.5 5 Greater than 1.5 to 2.0 133.5 6 Greater than 2.0 to 3.0 23.8 2 Greater than 3.0 to 4.0 26.1 2 Total $ 223.3 16 DSCR does not include residential mortgage loans. December 31, 2023 (in millions) Cost Loan Count Less than 1.00 $ 36.2 8 1.00 to 1.50 29.4 6 Greater than 1.5 to 2.0 30.9 6 Greater than 2.0 to 3.0 36.0 6 Greater than 3.0 to 4.0 12.3 2 Total $ 144.8 28 The following table presents loans by Loan To Value (“LTV”): September 30, 2024 (in millions) Cost Loan Count Greater than 50.0% to 55.0% $ 83.3 3 Greater than 55.0% to 60.0% 11.8 2 Greater than 60.0% to 70.0% 52.0 3 Greater than 70.0% 87.8 9 Total $ 234.9 17 December 31, 2023 (in millions) Cost Loan Count Equal to or less than 50.0% $ 12.3 2 Greater than 50.0% to 55.0% 9.1 2 Greater than 55.0% to 60.0% 18.9 4 Greater than 60.0% to 70.0% 37.3 6 Greater than 70.0% 67.2 14 Total $ 144.8 28
Schedule of Financing Receivable, before Allowance for Credit Loss, Maturity	The following table presents loans by maturity: September 30, 2024 (in millions) Cost Loan Count One Year or Less $ 34.9 3 Greater than One Year and Less than Three 128.1 5 Greater than Three Years and Less than Five Years 19.0 4 Greater than Five Years and Less than Seven Years — — Greater than Seven Years and Less than Ten Years 52.9 5 Total $ 234.9 17 December 31, 2023 (in millions) Cost Loan Count One Year or Less $ 19.7 4 Greater than One Year and Less than Three 34.9 6 Greater than Three Years and Less than Five Years 32.4 6 Greater than Five Years and Less than Seven Years 17.2 4 Greater than Seven Years and Less than Ten Years 40.6 8 Total $ 144.8 28
Schedule of Company's Investment and Other Gains and Losses	The following table presents our gross realized investment gains and losses: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Realized gains on fixed maturities and other: Fixed maturities $ 0.8 $ — $ 8.3 $ 0.6 Other investments, including short-term investments 0.5 2.9 4.2 13.1 Total realized gains on fixed maturities and other 1.3 2.9 12.5 13.7 Realized losses on fixed maturities and other: Fixed maturities (0.6) (1.4) (1.2) (25.1) Other investments, including short-term investments — (4.1) (5.0) (10.9) Total realized losses on fixed maturities and other (0.6) (5.5) (6.2) (36.0) Other net losses recognized on fixed maturities and other: Credit losses on fixed maturities (0.9) (2.0) (1.4) (5.0) Other (0.9) (3.2) (3.2) (6.7) Total other net losses recognized on fixed maturities and other (1.8) (5.2) (4.6) (11.7) Equity securities: Net realized gains (losses) on equity securities 0.5 9.2 — 6.9 Change in unrealized gains (losses) on equity securities held at the end of the period 0.4 (6.1) 29.1 6.1 Net gains (losses) on equity securities 0.9 3.1 29.1 13.0 Net investment and other gains (losses) before income taxes (0.2) (4.7) 30.8 (21.0) Income tax (benefit) provision (0.1) (0.5) 6.5 (5.8) Net investment and other gains (losses), net of income taxes $ (0.1) $ (4.2) $ 24.3 $ (15.2)
Schedule of Changes in Unrealized Appreciation (Depreciation)	Changes in unrealized gains (losses) related to fixed maturity investments are summarized as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Change in unrealized gains (losses) Fixed maturities $ 52.0 $ (19.5) $ 21.0 $ 26.9 Other and short-term investments 0.5 0.3 (0.1) (0.2) Net unrealized investment gains (losses) before income taxes 52.5 (19.2) 20.9 26.7 Income tax provision (benefit) 11.2 (3.7) 4.4 4.7 Net unrealized investment gains (losses), net of income taxes $ 41.3 $ (15.5) $ 16.5 $ 22.0
Schedule of Fair Value of Foreign Currency Exchange Forward Contracts	The fair value of our foreign currency exchange forward contracts as of September 30, 2024 and December 31, 2023 was as follows: As of September 30, 2024 December 31, 2023 (in millions) Notional Amount Fair Value Notional Amount Fair Value Operational currency Open contracts in a gain position $ — $ — $ 75.4 $ 1.8 Open contracts in a loss position — — 43.3 (0.3) Net open contracts for operational currency $ — $ 1.5 Asset manager investment exposure Open contracts in a loss position $ 78.3 (1.7) $ 45.8 $ (0.2) Net open contracts for asset manager investment exposure (1.7) (0.2) Total $ (1.7) $ 1.3
Schedule of Realized Gains and Losses of Investment on Foreign Currency Exchange Forward Contracts	The following table presents our gross realized investment gains and losses on our foreign currency exchange forward contracts: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Realized gains Operational currency exposure $ — $ 0.7 $ 2.8 $ 9.6 Asset manager investment exposure — 1.6 0.2 1.5 Gross realized investment gains — 2.3 3.0 11.1 Realized losses Operational currency exposure — (3.8) (3.6) (10.6) Asset manager investment exposure (1.7) — (1.7) — Gross realized investment losses (1.7) (3.8) (5.3) (10.6) Net realized investment (losses) gains on foreign currency exchange forward contracts $ (1.7) $ (1.5) $ (2.3) $ 0.5
Schedule of Restricted Assets	The following table presents our components of restricted investments: As of (in millions) September 30, 2024 December 31, 2023 Securities and cash on deposit for regulatory and other purposes $ 173.3 $ 153.4 Securities and cash pledged as collateral for letters of credit 40.0 109.2 Total restricted investments $ 213.3 $ 262.6
Schedule of Financial Assets Measured at Fair Value on Recurring Basis	Based on an analysis of the inputs, our financial assets and liabilities measured at fair value on a recurring basis have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) September 30, Level 1 (1) Level 2 (2) Level 3 (3) Fixed maturities U.S. Governments $ 264.9 $ 262.7 $ 2.2 $ — Foreign Governments 7.4 — 7.4 — Obligations of states and political subdivisions 85.2 — 85.2 — Corporate bonds 1,244.7 — 1,222.0 22.7 Commercial mortgage-backed securities 291.7 — 291.7 — Residential mortgage-backed securities 218.6 — 218.6 — Asset-backed securities 108.4 — 94.7 13.7 Collateralized loan obligations 147.3 — 147.3 — Total fixed maturities 2,368.2 262.7 2,069.1 36.4 Equity securities 85.3 3.4 — 81.9 Other investments 37.7 — — 37.7 Short-term investments 590.5 590.5 — — Derivatives 21.5 — 21.5 — Total assets $ 3,103.2 $ 856.6 $ 2,090.6 $ 156.0 Derivatives 1.7 — 1.7 — Total liabilities $ 1.7 $ — $ 1.7 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, Level 1 (1) Level 2 (2) Level 3 (3) Fixed maturities U.S. Governments $ 362.2 $ 360.1 $ 2.1 $ — Foreign Governments 30.3 — 30.3 — Obligations of states and political subdivisions 94.4 — 94.4 — Corporate bonds 1,213.1 — 1,180.5 32.6 Commercial mortgage-backed securities 280.5 — 280.5 — Residential mortgage-backed securities 248.8 — 248.8 — Asset-backed securities 142.0 — 124.2 17.8 Collateralized loan obligations 214.1 — 214.1 — Total fixed maturities 2,585.4 360.1 2,174.9 50.4 Equity securities 10.7 4.3 — 6.4 Other investments 0.2 — 0.2 — Short-term investments 429.5 429.0 0.5 — Derivatives 1.3 — 1.3 — Total assets $ 3,027.1 $ 793.4 $ 2,176.9 $ 56.8 (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs
Schedule of Reconciliation of Beginning and Ending Balances for Investments Categorized as Level 3	A reconciliation of the beginning and ending balances for the investments categorized as Level 3 are as follows: Fair Value Measurements Using Unobservable Inputs (Level 3) (in millions) Fixed Maturities Equity Other Investments Total Beginning balance, January 1, 2024 $ 50.4 $ 6.4 $ — $ 56.8 Transfers into Level 3 0.7 — — 0.7 Transfers out of Level 3 (10.1) — — (10.1) Total gains or losses (realized/unrealized): Included in net income 1.2 28.3 — 29.5 Included in other comprehensive income — — — — Purchases, issuances, sales, and settlements: Purchases 1.9 47.2 49.8 98.9 Sales — — — — Settlements (7.7) — (12.1) (19.8) Ending balance, September 30, 2024 $ 36.4 $ 81.9 $ 37.7 $ 156.0 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at September 30, 2024 $ — $ 29.3 $ — $ 29.3 (in millions) Fixed Maturities Equity Total Beginning balance, January 1, 2023 $ 40.7 $ 15.5 $ 56.2 Transfers into Level 3 5.6 — 5.6 Transfers out of Level 3 (5.6) (7.6) (13.2) Total gains or losses (realized/unrealized): Included in net income (0.1) (0.4) (0.5) Included in other comprehensive loss 0.8 — 0.8 Purchases, issuances, sales, and settlements: Purchases 10.6 — 10.6 Sales (0.5) (1.1) (1.6) Settlements (1.1) — (1.1) Ending balance, December 31, 2023 $ 50.4 $ 6.4 $ 56.8 Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at December 31, 2023 $ — $ (0.8) $ (0.8)
Schedule of Company's Financial Instruments Whose Carrying Amount Did Not Equal Fair Value	The Company holds certain investments at cost, less an allowance for expected credit losses, on the Condensed Consolidated Balance Sheets. The fair value of the Company’s investments is estimated using a discounted cash flow analysis. Due to the level of unobservable inputs factored into the estimation of fair value, the valuation would be categorized as Level 3. The cost and estimated fair value of these investments were: As of September 30, 2024 December 31, 2023 (in millions) Cost Fair Value Cost Fair Value Mortgage loans $ 234.9 $ 240.3 $ 144.8 $ 148.8 Private loans 200.7 201.8 — — Total $ 435.6 $ 442.1 $ 144.8 $ 148.8 A summary of our financial instruments whose carrying value did not equal fair value is shown below: September 30, 2024 December 31, 2023 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 161.7 $ 172.7 $ 160.8 $ 165.9 Subordinated debentures 81.0 84.9 80.4 83.3 Total junior subordinated debentures 242.7 257.6 241.2 249.2 Senior unsecured fixed rate notes 128.7 130.4 128.0 132.7 $ 371.4 $ 388.0 $ 369.2 $ 381.9

Allowance for Credit Losses (Ta

Allowance for Credit Losses (Tables)	9 Months Ended
	Sep. 30, 2024
Credit Loss [Abstract]
Schedule of Premium Receivable, Allowance for Credit Loss	The following table presents the balances of premiums receivable, net of allowance for estimated uncollectible premiums, including expected lifetime credit losses and the changes in the allowance for the respective periods: (in millions) Premiums Receivable, Net of Allowance for Estimated Uncollectible Premiums Allowance for Estimated Uncollectible Premiums Successor Balance, December 31, 2023 $ 230.7 $ 3.0 Current period change for estimated uncollectible premiums 3.0 Write-offs of uncollectible premiums receivable (1.8) Balance, September 30, 2024 $ 191.7 $ 4.2 Predecessor Balance, December 31, 2022 $ 292.0 $ 4.7 Current period change for estimated uncollectible premiums 5.1 Write-offs of uncollectible premiums receivable (2.4) Balance, September 30, 2023 $ 269.7 $ 7.4
Schedule of Reinsurance Recoverable, Allowance for Credit Loss	Reinsurance Recoverables The following table presents the balances of reinsurance recoverables, net of the allowance for estimated uncollectible reinsurance, including expected credit losses and changes in the allowance for the respective periods: (in millions) Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance Allowance for Estimated Uncollectible Reinsurance Successor Balance, December 31, 2023 $ 2,959.3 $ — Balance, September 30, 2024 $ 3,130.7 $ — Predecessor Balance, December 31, 2022 $ 3,029.1 $ 4.7 Balance, September 30, 2023 $ 2,889.6 $ 4.7

Reserves for Losses and Loss _2

Reserves for Losses and Loss Adjustment Expenses (Tables)	9 Months Ended
	Sep. 30, 2024
Insurance [Abstract]
Schedule of Reserves for Losses and Loss Adjustment Expenses	The following table provides a reconciliation of reserves for losses and loss adjustment expenses (“LAE”): Successor Predecessor (in millions) Nine Months Ended Nine Months Ended Net reserves - beginning of the year $ 2,747.1 $ 2,213.1 Add: Losses and LAE incurred during current calendar year, net of reinsurance: Current accident year 583.8 680.9 Prior accident years 209.7 126.0 Losses and LAE incurred during calendar year, net of reinsurance 793.5 806.9 Deduct: Losses and LAE payments made during current calendar year, net of reinsurance: Current accident year 53.2 94.9 Prior accident years 552.6 361.6 Losses and LAE payments made during current calendar year, net of reinsurance: 605.8 456.5 Add/(Deduct): Divestitures (1) — 24.4 Retroactive reinsurance (2) — 21.7 Deferred gain on U.S. loss portfolio transfer, net of amortization — (16.8) Purchase accounting adjustment (3) 19.4 — Total net reserve adjustments 19.4 29.3 Foreign exchange adjustments (1.6) 0.9 Net reserves - end of period 2,952.6 2,593.7 Add: Reinsurance recoverables on unpaid losses and LAE, end of period 2,840.3 2,735.0 Gross reserves - end of period $ 5,792.9 $ 5,328.7 (1) For the nine months ended September 30, 2023, the adjustment relates to the year-to-date activity of Syndicate 1200 and on reinsurance contracts with AUA subsidiaries. Refer to the sale of Argo Underwriting Agency Limited in Note 1, “Business and Significant Accounting Policies” for additional information. (2) In connection with the sale of AUA, the Company entered into two retroactive reinsurance agreements with AUA subsidiaries. (3) Impact of measurement period adjustment in connection with the Merger. R efer to Note 1, “Business and Significant Accounting Policies” for additional information.
Schedule of Impact from (Favorable) Unfavorable Development of Prior Accident Years’ Loss and LAE Reserves on Each Reporting Segment	The impact from the unfavorable (favorable) development of prior accident years’ loss and LAE reserves on each reporting segment is presented below: Successor Predecessor (in millions) Nine Months Ended Nine Months Ended U.S. Operations $ 125.1 $ 111.7 International Operations 77.3 11.7 Run-off Lines 7.3 2.6 Total unfavorable (favorable) prior-year development $ 209.7 $ 126.0

Disclosures About Fair Value _2

Disclosures About Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Company's Financial Instruments Whose Carrying Amount Did Not Equal Fair Value	The Company holds certain investments at cost, less an allowance for expected credit losses, on the Condensed Consolidated Balance Sheets. The fair value of the Company’s investments is estimated using a discounted cash flow analysis. Due to the level of unobservable inputs factored into the estimation of fair value, the valuation would be categorized as Level 3. The cost and estimated fair value of these investments were: As of September 30, 2024 December 31, 2023 (in millions) Cost Fair Value Cost Fair Value Mortgage loans $ 234.9 $ 240.3 $ 144.8 $ 148.8 Private loans 200.7 201.8 — — Total $ 435.6 $ 442.1 $ 144.8 $ 148.8 A summary of our financial instruments whose carrying value did not equal fair value is shown below: September 30, 2024 December 31, 2023 (in millions) Carrying Fair Carrying Fair Junior subordinated debentures: Trust preferred debentures $ 161.7 $ 172.7 $ 160.8 $ 165.9 Subordinated debentures 81.0 84.9 80.4 83.3 Total junior subordinated debentures 242.7 257.6 241.2 249.2 Senior unsecured fixed rate notes 128.7 130.4 128.0 132.7 $ 371.4 $ 388.0 $ 369.2 $ 381.9
Schedule of Fair Value, Assets Measured on Recurring and Nonrecurring Basis	Based on an analysis of the inputs, our financial instruments measured at fair value for disclosure purposes have been categorized as follows: Fair Value Measurements at Reporting Date Using (in millions) September 30, 2024 Level 1 (1) Level 2 (2) Level 3 (3) Junior subordinated debentures: Trust preferred debentures $ 172.7 $ — $ 172.7 $ — Subordinated debentures 84.9 — 84.9 — Total junior subordinated debentures 257.6 — 257.6 — Senior unsecured fixed rate notes 130.4 130.4 — — $ 388.0 $ 130.4 $ 257.6 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs Fair Value Measurements at Reporting Date Using (in millions) December 31, 2023 Level 1 (1) Level 2 (2) Level 3 (3) Junior subordinated debentures: Trust preferred debentures $ 165.9 $ — $ 165.9 $ — Subordinated debentures 83.3 — 83.3 — Total junior subordinated debentures 249.2 — 249.2 — Senior unsecured fixed rate notes 132.7 132.7 — — $ 381.9 $ 132.7 $ 249.2 $ — (1) Quoted prices in active markets for identical assets (2) Significant other observable inputs (3) Significant unobservable inputs

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 2024
Equity [Abstract]
Schedule of Changes in Accumulated Other Comprehensive (Loss) Income	A summary of changes in accumulated other comprehensive income (loss), net of taxes (where applicable) by component for the nine months ended September 30, 2024 and 2023 is presented below: (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2024 $ 0.1 $ 51.1 $ 0.6 $ 51.8 Other comprehensive income (loss) before reclassifications 0.3 20.3 — 20.6 Amounts reclassified from accumulated other comprehensive income — (3.8) — (3.8) Net current-period other comprehensive income (loss) 0.3 16.5 — 16.8 Balance, September 30, 2024 $ 0.4 $ 67.6 $ 0.6 $ 68.6 (in millions) Foreign Currency Translation Adjustments Unrealized Defined Benefit Pension Plans Total Balance, January 1, 2023 $ (4.2) $ (293.1) $ (7.8) $ (305.1) Other comprehensive income (loss) before reclassifications 1.0 (0.4) 0.8 1.4 Amounts reclassified from accumulated other comprehensive loss — 22.4 — 22.4 Net current-period other comprehensive income (loss) 1.0 22.0 0.8 23.8 Balance, September 30, 2023 $ (3.2) $ (271.1) $ (7.0) $ (281.3)
Schedule of Amounts Reclassified from Accumulated Other Comprehensive (Loss) Income	The amounts reclassified from accumulated other comprehensive income (loss) shown in the above table have been included in the following captions in our Condensed Consolidated Statements of Income (Loss): Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Unrealized gains and losses on securities: Net realized investment and other gains (losses) $ (1.6) $ (1.5) $ 4.8 $ (27.4) Income tax provision (benefit) 0.3 (0.4) (1.0) 5.0 Total, net of taxes $ (1.3) $ (1.9) $ 3.8 $ (22.4)

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2024
Supplemental Cash Flow Elements [Abstract]
Schedule of Interest Paid and Income Taxes Paid (Recovered)	Interest paid and income taxes paid (recovered) were as follows: Successor Predecessor (in millions) Nine Months Ended Nine Months Ended Senior unsecured fixed rate notes $ 7.0 $ 7.0 Junior subordinated debentures 18.6 17.2 Other indebtedness 1.9 0.8 Total interest paid $ 27.5 $ 25.0 Income taxes paid $ 0.1 $ 0.2 Income taxes recovered (31.3) (0.1) Income taxes paid (recovered), net $ (31.2) $ 0.1 Condensed Consolidated Statement of Cash Flows for the nine months ended September 30, 2024 excludes $3.3 million of noncash activity for a lease which commenced in 2024. The lease is reflected on our Condensed Consolidated Balance Sheets in Operating lease right-of-use assets and Operating lease liabilities.

Underwriting, Acquisition and_2

Underwriting, Acquisition and General Expenses (Tables)	9 Months Ended
	Sep. 30, 2024
Underwriting, Acquisition and Insurance Expenses [Abstract]
Schedule of Underwriting, Acquisition and General Expenses	Underwriting, acquisition and general expenses were as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Commission expense $ 7.6 $ 46.6 $ 65.2 $ 144.5 Other underwriting and insurance expenses 62.6 74.0 195.0 230.2 Amortization of value of business acquired and other intangible assets 43.0 — 129.1 — Total 113.2 120.6 389.3 374.7 Net deferral of policy acquisition costs (2.3) (4.5) (44.5) (10.7) Total underwriting, acquisition and general expenses $ 110.9 $ 116.1 $ 344.8 $ 364.0

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates	For the three and nine months ended September 30, 2024 and 2023, pre-tax income (loss) attributable to our operations and the corresponding operations’ effective tax rates were as follows: Successor Predecessor Three Months Ended Three Months Ended (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ — — % $ (9.8) — % United States (163.9) 21.0 % (18.1) (95.5) % United Kingdom (2.1) — % (1.6) (22.5) % Barbados — — % — (1) — % Ireland — — % — (1) — % Italy (0.7) — % 0.2 20.0 % Pre-tax income (loss) $ (166.7) 20.6 % $ (29.3) (60.1) % (1) Pre-tax income (loss) for the respective year was less than $0.1 million. Successor Predecessor Nine Months Ended Nine Months Ended (in millions) Pre-Tax Effective Pre-Tax Effective Bermuda $ — — % $ (21.1) — % United States (114.1) 23.9 % (31.2) (32.9) % United Kingdom (4.4) — % (23.2) 30.4 % Barbados — — % — (1) — % United Arab Emirates — — % 0.3 — % Ireland — — % (0.1) — % Italy (2.7) (1.4) % 0.1 50.3 % Pre-tax income (loss) $ (121.2) 22.5 % $ (75.2) (4.4) % (1) Pre-tax income (loss) for the respective year was less than $0.1 million.
Schedule of Reconciliation of Difference Between Provision for Income Taxes and Expected Tax Provision at Weighted Average Tax Rate	A reconciliation of the difference between the provision (benefit) for income taxes and the expected tax provision (benefit) at the weighted average tax rate is as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Income tax provision (benefit) at expected rate $ (35.1) $ (4.1) $ (25.7) $ (11.0) Tax effect of: Nontaxable investment income — — (0.2) (0.1) Foreign exchange adjustments — — — (2.6) Base Erosion and Anti-Abuse Tax — 20.4 — 16.9 Withholding taxes — — — 0.1 Ireland Capital Loss — — 3.3 — U.S. state tax expense, net of federal income tax effect — — — (1.2) Change in uncertain tax position liability — 0.2 — 1.2 Change in valuation allowance 0.3 — (2.2) 0.1 Impact of change in tax rate related to Finance Act 2021 — — — (0.4) Prior period adjustment (0.3) 0.2 (3.6) 0.1 Other 0.7 0.9 1.2 0.2 Income tax provision (benefit) $ (34.4) $ 17.6 $ (27.2) $ 3.3

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2024
Segment Reporting [Abstract]
Schedule of Revenue and Income (Loss) Before Income Taxes for Each Segment	Revenue and income (loss) before income taxes for each segment were as follows: Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Revenue: Net earned premiums U.S. Operations $ 210.4 $ 314.1 $ 761.9 $ 950.9 International Operations 23.9 28.5 75.8 111.4 Run-off Lines — 0.1 0.2 0.2 Total net earned premiums 234.3 342.7 837.9 1,062.5 Net investment income U.S. Operations 52.3 33.2 158.4 84.7 International Operations 7.6 6.2 22.8 15.8 Run-off Lines 2.4 1.0 5.9 2.4 Total net investment income 62.3 40.4 187.1 102.9 Net investment and other gains (losses) (0.2) (4.7) 30.8 (21.0) Total revenue $ 296.4 $ 378.4 $ 1,055.8 $ 1,144.4 Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended Income (loss) before income taxes U.S. Operations $ (100.3) $ (14.0) $ (74.3) $ (23.2) International Operations (67.1) (2.6) (70.1) 9.3 Run-off Lines (5.7) — (5.1) (1.0) Total segment income (loss) before income taxes (173.1) (16.6) (149.5) (14.9) Corporate and Other 2.8 (11.3) (5.6) (39.2) Net investment and other gains (losses) (0.2) (4.7) 30.8 (21.0) Foreign currency exchange gains (losses) 3.8 3.3 3.1 (0.1) Total income (loss) before income taxes $ (166.7) $ (29.3) $ (121.2) $ (75.2)
Schedule of Earned Premiums by Geographic Location	The table below presents net earned premiums by geographic location for the three and nine months ended September 30, 2024 and 2023. For this disclosure, we determine geographic location by the country of domicile of our subsidiaries that underwrite the business and not by the location of insureds or reinsureds from whom the business was generated. Successor Predecessor Successor Predecessor (in millions) Three Months Ended Three Months Ended Nine Months Ended Nine Months Ended United States $ 210.4 $ 314.2 $ 762.1 $ 951.1 United Kingdom — — — 48.3 Bermuda 23.9 28.5 75.8 63.1 Total earned premiums $ 234.3 $ 342.7 $ 837.9 $ 1,062.5
Schedule of Identifiable Assets	The following table represents identifiable assets: As of (in millions) September 30, 2024 December 31, 2023 U.S. Operations $ 6,788.6 $ 6,279.0 International Operations 1,705.9 1,888.9 Run-off Lines 215.7 221.4 Corporate and Other 106.4 113.8 Total assets $ 8,816.6 $ 8,503.1

Business and Significant Acco_3

Business and Significant Accounting Policies (Details) $ / shares in Units, $ in Millions				3 Months Ended			9 Months Ended		20 Months Ended
	Sep. 25, 2024 USD ($) $ / shares shares	Jul. 01, 2024 USD ($)	Feb. 02, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares		Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares		Sep. 30, 2024 USD ($) $ / shares shares	Sep. 24, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Common shares, shares authorized (in shares) | shares	1,000			1,000			1,000		1,000	2,000,000,000	2,000,000,000
Common shares, par value (in dollars per share) | $ / shares	$ 0.01			$ 0.01			$ 0.01		$ 0.01	$ 1	$ 1
Preferred shares, shares authorized (in shares) | shares	10,000			10,000			10,000		10,000	30,000,000	30,000,000
Purchase accounting adjustments				$ 15.3	[1]		$ 15.3	[2]
AGIH Merger Sub, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Acquisition, Stock Conversion Ratio	0.000001
Initial bargain purchase gain	$ 48.9
Purchase accounting adjustments				15.3
Bargain purchase				$ 33.6
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Argo Global Holdings Ltd
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Final consideration paid		$ 86.7
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Argo Underwriting Agency Limited
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash consideration received from sale			$ 161.3
Proceeds from sale of Trident assets			130.7
Consideration placed in escrow			$ 30.6
Consideration placed in escrow, term			2 years
Consideration placed in escrow that has been released to the company									$ 13.1
Loss on disposal						$ 20.3
[1] (1) Impact of measurement period adjustment on bargain purchase in connection with the Merger. R efer to Note 1, “Business and Significant Accounting Policies” for additional information. (2) Refer to the Merger with AGIH Merger Sub, Inc. in Note 1, “Business and Significant Accounting Policies” for additional information.

Investments - Schedule of Amort

Investments - Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Fair Value of Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Fixed maturities
Amortized Cost	$ 2,283.6		$ 2,521.5
Gross Unrealized Gains	86.9		65.5
Gross Unrealized Losses	1.3		1.4
Allowance for Credit Losses	1	$ 0.5	0.2	$ 4.4	$ 2.5	$ 2.8
Fair Value	2,368.2		2,585.4
U.S. Governments
Fixed maturities
Amortized Cost	259.8		357.7
Gross Unrealized Gains	5.2		4.5
Gross Unrealized Losses	0.1		0
Allowance for Credit Losses	0		0
Fair Value	264.9		362.2
Foreign Governments
Fixed maturities
Amortized Cost	7.1		27.9
Gross Unrealized Gains	0.3		2.6
Gross Unrealized Losses	0		0
Allowance for Credit Losses	0		0.2
Fair Value	7.4		30.3
Obligations of states and political subdivisions
Fixed maturities
Amortized Cost	82.2		92.4
Gross Unrealized Gains	3		2
Gross Unrealized Losses	0		0
Allowance for Credit Losses	0		0
Fair Value	85.2		94.4
Corporate bonds
Fixed maturities
Amortized Cost	1,206.7		1,185
Gross Unrealized Gains	39.9		28.9
Gross Unrealized Losses	0.9		0.8
Allowance for Credit Losses	1		0
Fair Value	1,244.7		1,213.1
Commercial mortgage-backed securities
Fixed maturities
Amortized Cost	275.1		270.9
Gross Unrealized Gains	16.9		10.1
Gross Unrealized Losses	0.3		0.5
Allowance for Credit Losses	0		0
Fair Value	291.7		280.5
Residential mortgage-backed securities
Fixed maturities
Amortized Cost	204.9		235.2
Gross Unrealized Gains	13.7		13.6
Gross Unrealized Losses	0		0
Allowance for Credit Losses	0		0
Fair Value	218.6		248.8
Asset-backed securities
Fixed maturities
Amortized Cost	104.9		140.4
Gross Unrealized Gains	3.5		1.7
Gross Unrealized Losses	0		0.1
Allowance for Credit Losses	0		0
Fair Value	108.4		142
Collateralized loan obligations
Fixed maturities
Amortized Cost	142.9		212
Gross Unrealized Gains	4.4		2.1
Gross Unrealized Losses	0		0
Allowance for Credit Losses	0		0
Fair Value	$ 147.3		$ 214.1

Investments - Schedule of Amo_2

Investments - Schedule of Amortized Cost and Fair Values of Fixed Maturity Investments, by Contractual Maturity (Details) $ in Millions	Sep. 30, 2024 USD ($)
Amortized Cost
Due in one year or less	$ 304.5
Due after one year through five years	1,039.3
Due after five years through ten years	191.9
Due after ten years	20.1
Structured securities	727.8
Total	2,283.6
Fair Value
Due in one year or less	306.4
Due after one year through five years	1,067.4
Due after five years through ten years	206.8
Due after ten years	21.6
Structured securities	766
Total	$ 2,368.2

Investments - Schedule of Carry

Investments - Schedule of Carrying Value and Unfunded Investment Commitments of Other Invested Assets Portfolio (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Carrying Value	$ 3,976	$ 3,481.2
Unfunded Commitments	112.6	93.4
Hedge funds
Schedule of Investments [Line Items]
Carrying Value	28.7	56.2
Unfunded Commitments	0	0
Private equity
Schedule of Investments [Line Items]
Carrying Value	258.4	250.3
Unfunded Commitments	82.2	93.4
Real estate equity investments
Schedule of Investments [Line Items]
Carrying Value	101	0
Unfunded Commitments	0	0
Other
Schedule of Investments [Line Items]
Carrying Value	42.2	4.5
Unfunded Commitments	30.4	0
Other Investments
Schedule of Investments [Line Items]
Carrying Value	$ 430.3	$ 311

Investments - Schedule of Aging

Investments - Schedule of Aging of Unrealized Losses on Company's Investments in Fixed Maturities, Equity Securities and Other Investments (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	$ 54.7	$ 107.2
Unrealized Losses, Less Than One Year	1.3	1.4
Fair Value, One Year or Greater	0	0
Unrealized Losses, One Year or Greater	0	0
Fair Value, Total	54.7	107.2
Unrealized Losses, Total	1.3	1.4
U.S. Governments
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	17.9
Unrealized Losses, Less Than One Year	0.1
Fair Value, One Year or Greater	0
Unrealized Losses, One Year or Greater	0
Fair Value, Total	17.9
Unrealized Losses, Total	0.1
Foreign Governments
Schedule of Investments [Line Items]
Fair Value, Less Than One Year		0.1
Unrealized Losses, Less Than One Year		0
Fair Value, One Year or Greater		0
Unrealized Losses, One Year or Greater		0
Fair Value, Total		0.1
Unrealized Losses, Total		0
Obligations of states and political subdivisions
Schedule of Investments [Line Items]
Fair Value, Less Than One Year		0.5
Unrealized Losses, Less Than One Year		0
Fair Value, One Year or Greater		0
Unrealized Losses, One Year or Greater		0
Fair Value, Total		0.5
Unrealized Losses, Total		0
Corporate bonds
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	17.6	38.7
Unrealized Losses, Less Than One Year	0.9	0.8
Fair Value, One Year or Greater	0	0
Unrealized Losses, One Year or Greater	0	0
Fair Value, Total	17.6	38.7
Unrealized Losses, Total	0.9	0.8
Commercial mortgage-backed securities
Schedule of Investments [Line Items]
Fair Value, Less Than One Year	19.2	32.2
Unrealized Losses, Less Than One Year	0.3	0.5
Fair Value, One Year or Greater	0	0
Unrealized Losses, One Year or Greater	0	0
Fair Value, Total	19.2	32.2
Unrealized Losses, Total	$ 0.3	0.5
Residential mortgage-backed securities
Schedule of Investments [Line Items]
Fair Value, Less Than One Year		2.9
Unrealized Losses, Less Than One Year		0
Fair Value, One Year or Greater		0
Unrealized Losses, One Year or Greater		0
Fair Value, Total		2.9
Unrealized Losses, Total		0
Asset-backed securities
Schedule of Investments [Line Items]
Fair Value, Less Than One Year		11.4
Unrealized Losses, Less Than One Year		0.1
Fair Value, One Year or Greater		0
Unrealized Losses, One Year or Greater		0
Fair Value, Total		11.4
Unrealized Losses, Total		0.1
Collateralized loan obligations
Schedule of Investments [Line Items]
Fair Value, Less Than One Year		21.4
Unrealized Losses, Less Than One Year		0
Fair Value, One Year or Greater		0
Unrealized Losses, One Year or Greater		0
Fair Value, Total		21.4
Unrealized Losses, Total		$ 0

Investments - Additional Inform

Investments - Additional Information (Details)	Sep. 30, 2024 security
Investments, Debt and Equity Securities [Abstract]
Number of securities in an unrealized loss position, total	1,152
Number of securities in an unrealized loss position for less than one year	51
Number of securities in an unrealized loss position for a period of one year or greater	0

Investments - Schedule of Allow

Investments - Schedule of Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 0.5	$ 2.5	$ 0.2	$ 2.8
Securities for which allowance was not previously recorded	0.2	1.9	0.6	2.7
Securities sold during the period		(0.1)	(0.1)	(0.5)
Additional net increases (decreases) in existing allowance	0.3	0.1	0.3	(0.6)
Ending balance	1	4.4	1	4.4
Foreign Governments
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	1	0.2	0.7
Securities for which allowance was not previously recorded	0	0	0	0.1
Securities sold during the period		0	0	0
Additional net increases (decreases) in existing allowance	0	0.1	(0.2)	0.3
Ending balance	0	1.1	0	1.1
Obligations of states and political subdivisions
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0	0	0.4
Securities for which allowance was not previously recorded	0	0.5	0	0.5
Securities sold during the period		0	0	0
Additional net increases (decreases) in existing allowance	0	0	0	(0.4)
Ending balance	0	0.5	0	0.5
Corporate bonds
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0.5	1.4	0	1.6
Securities for which allowance was not previously recorded	0.2	1.4	0.6	2.1
Securities sold during the period		(0.1)	(0.1)	(0.5)
Additional net increases (decreases) in existing allowance	0.3	0	0.5	(0.5)
Ending balance	1	2.7	1	2.7
Asset-backed securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Beginning balance	0	0.1	0	0.1
Securities for which allowance was not previously recorded	0	0	0	0
Securities sold during the period		0	0	0
Additional net increases (decreases) in existing allowance	0	0	0	0
Ending balance	$ 0	$ 0.1	$ 0	$ 0.1

Investments - Schedule of Comme

Investments - Schedule of Commercial Mortgage Loans (Details) $ in Millions	Sep. 30, 2024 USD ($) loan	Dec. 31, 2023 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 234.9	$ 144.8
Composition	100%	100%
Loan Count | loan	17	28
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 11.6
Composition	4.90%
Loan Count | loan	1
Apartments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 69.5	$ 76.1
Composition	29.60%	52.60%
Loan Count | loan	9	16
Hotel
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 12.5	$ 22.4
Composition	5.30%	15.40%
Loan Count | loan	1	4
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 95.6	$ 26
Composition	40.70%	18%
Loan Count | loan	3	4
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 26
Composition	11.10%
Loan Count | loan	1
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 19.7	$ 20.3
Composition	8.40%	14%
Loan Count | loan	2	4

Investments - Schedule of Loans

Investments - Schedule of Loans by Ratio (Details) $ in Millions	Sep. 30, 2024 USD ($) loan	Dec. 31, 2023 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 234.9	$ 144.8
Loan Count | loan	17	28
Excluding Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 223.3
Loan Count | loan	16
Equal to or less than 50.0%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $		$ 12.3
Loan Count | loan		2
Greater than 50.0% to 55.0%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 83.3	$ 9.1
Loan Count | loan	3	2
Greater than 55.0% to 60.0%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 11.8	$ 18.9
Loan Count | loan	2	4
Greater than 60.0% to 70.0%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 52	$ 37.3
Loan Count | loan	3	6
Greater than 70.0%
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 87.8	$ 67.2
Loan Count | loan	9	14
Less than 1.00
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 10.4	$ 36.2
Loan Count | loan	1	8
1.00 to 1.50
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 29.5	$ 29.4
Loan Count | loan	5	6
Greater than 1.5 to 2.0
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 133.5	$ 30.9
Loan Count | loan	6	6
Greater than 2.0 to 3.0
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 23.8	$ 36
Loan Count | loan	2	6
Greater than 3.0 to 4.0
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost | $	$ 26.1	$ 12.3
Loan Count | loan	2	2

Investments - Schedule of Loa_2

Investments - Schedule of Loans by Maturity (Details) $ in Millions	Sep. 30, 2024 USD ($) loan	Dec. 31, 2023 USD ($) loan
Cost
One Year or Less | $	$ 34.9	$ 19.7
Greater than One Year and Less than Three | $	128.1	34.9
Greater than Three Years and Less than Five Years | $	19	32.4
Greater than Five Years and Less than Seven Years | $	0	17.2
Greater than Seven Years and Less than Ten Years | $	52.9	40.6
Cost | $	$ 234.9	$ 144.8
Loan Count
One Year or Less | loan	3	4
Greater than One Year and Less than Three | loan	5	6
Greater than Three Years and Less than Five Years | loan	4	6
Greater than Five Years and Less than Seven Years | loan	0	4
Greater than Seven Years and Less than Ten Years | loan	5	8
Loan Count | loan	17	28

Investments - Schedule of Compa

Investments - Schedule of Company's Gross Realized Investment Other Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other:	$ 1.3	$ 2.9	$ 12.5	$ 13.7
Realized losses on fixed maturities and other:	(0.6)	(5.5)	(6.2)	(36)
Other	(0.9)	(3.2)	(3.2)	(6.7)
Total other net losses recognized on fixed maturities and other	(1.8)	(5.2)	(4.6)	(11.7)
Net realized gains (losses) on equity securities	0.5	9.2	0	6.9
Change in unrealized gains (losses) on equity securities held at the end of the period	0.4	(6.1)	29.1	6.1
Net gains (losses) on equity securities	0.9	3.1	29.1	13
Net investment and other gains (losses) before income taxes	(0.2)	(4.7)	30.8	(21)
Income tax (benefit) provision	(0.1)	(0.5)	6.5	(5.8)
Net investment and other gains (losses), net of income taxes	(0.1)	(4.2)	24.3	(15.2)
Fixed maturities
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other:	0.8	0	8.3	0.6
Realized losses on fixed maturities and other:	(0.6)	(1.4)	(1.2)	(25.1)
Other investments, including short-term investments
Schedule of Investments [Line Items]
Realized gains on fixed maturities and other:	0.5	2.9	4.2	13.1
Realized losses on fixed maturities and other:	0	(4.1)	(5)	(10.9)
Credit losses on fixed maturities
Schedule of Investments [Line Items]
Credit losses on fixed maturities	$ (0.9)	$ (2)	$ (1.4)	$ (5)

Investments - Schedule of Chang

Investments - Schedule of Changes in Unrealized Appreciation (Depreciation) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule of Investments [Line Items]
Net unrealized investment gains (losses) before income taxes	$ 52.5	$ (19.2)	$ 20.9	$ 26.7
Income tax provision (benefit)	11.2	(3.7)	4.4	4.7
Net unrealized investment gains (losses), net of income taxes	41.3	(15.5)	16.5	22
Fixed maturities
Schedule of Investments [Line Items]
Net unrealized investment gains (losses) before income taxes	52	(19.5)	21	26.9
Other and short-term investments
Schedule of Investments [Line Items]
Net unrealized investment gains (losses) before income taxes	$ 0.5	$ 0.3	$ (0.1)	$ (0.2)

Investments - Schedule of Fair

Investments - Schedule of Fair Value of Foreign Currency Exchange Forward Contracts (Details) - Foreign Currency Exchange Forward Contracts - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	$ (1.7)	$ 1.3
Operational currency
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	0	1.5
Open contracts in a gain position
Schedule of Investments [Line Items]
Foreign currency exchange, notional amount	0	75.4
Foreign currency exchange, fair value	0	1.8
Open contracts in a loss position
Schedule of Investments [Line Items]
Foreign currency exchange, notional amount	0	43.3
Foreign currency exchange, fair value	0	(0.3)
Asset manager investment exposure
Schedule of Investments [Line Items]
Foreign currency exchange, fair value	(1.7)	(0.2)
Open contracts in a loss position
Schedule of Investments [Line Items]
Foreign currency exchange, notional amount	78.3	45.8
Foreign currency exchange, fair value	$ (1.7)	$ (0.2)

Investments - Schedule of Reali

Investments - Schedule of Realized Gains and Losses of Investment on Foreign Currency Exchange Forward Contracts (Details) - Foreign Currency Exchange Forward Contracts - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule of Investments [Line Items]
Gross realized investment gains	$ 0	$ 2.3	$ 3	$ 11.1
Gross realized investment losses	(1.7)	(3.8)	(5.3)	(10.6)
Net realized investment (losses) gains on foreign currency exchange forward contracts	(1.7)	(1.5)	(2.3)	0.5
Operational currency
Schedule of Investments [Line Items]
Gross realized investment gains	0	0.7	2.8	9.6
Gross realized investment losses	0	(3.8)	(3.6)	(10.6)
Asset manager investment exposure
Schedule of Investments [Line Items]
Gross realized investment gains	0	1.6	0.2	1.5
Gross realized investment losses	$ (1.7)	$ 0	$ (1.7)	$ 0

Investments - Schedule of Compo

Investments - Schedule of Components of Restricted Assets (Details) - Asset Pledged as Collateral - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Restricted investments	$ 213.3	$ 262.6
Securities and cash on deposit for regulatory and other purposes
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Restricted investments	173.3	153.4
Securities and cash pledged as collateral for letters of credit
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Restricted investments	$ 40	$ 109.2

Investments - Schedule of Finan

Investments - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	$ 3,976	$ 3,481.2
Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivatives	21.5	1.3
Total assets	3,103.2	3,027.1
Derivatives	1.7
Total liabilities	1.7
Fair Value, Recurring | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	2,368.2	2,585.4
Fair Value, Recurring | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	147.3	214.1
Fair Value, Recurring | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	264.9	362.2
Fair Value, Recurring | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	7.4	30.3
Fair Value, Recurring | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	85.2	94.4
Fair Value, Recurring | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	1,244.7	1,213.1
Fair Value, Recurring | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	291.7	280.5
Fair Value, Recurring | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	218.6	248.8
Fair Value, Recurring | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	108.4	142
Fair Value, Recurring | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	85.3	10.7
Fair Value, Recurring | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	37.7	0.2
Fair Value, Recurring | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	590.5	429.5
Fair Value, Recurring | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivatives	0	0
Total assets	856.6	793.4
Derivatives	0
Total liabilities	0
Fair Value, Recurring | Level 1 | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	262.7	360.1
Fair Value, Recurring | Level 1 | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	262.7	360.1
Fair Value, Recurring | Level 1 | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	3.4	4.3
Fair Value, Recurring | Level 1 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 1 | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	590.5	429
Fair Value, Recurring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivatives	21.5	1.3
Total assets	2,090.6	2,176.9
Derivatives	1.7
Total liabilities	1.7
Fair Value, Recurring | Level 2 | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	2,069.1	2,174.9
Fair Value, Recurring | Level 2 | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	147.3	214.1
Fair Value, Recurring | Level 2 | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	2.2	2.1
Fair Value, Recurring | Level 2 | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	7.4	30.3
Fair Value, Recurring | Level 2 | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	85.2	94.4
Fair Value, Recurring | Level 2 | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	1,222	1,180.5
Fair Value, Recurring | Level 2 | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	291.7	280.5
Fair Value, Recurring | Level 2 | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	218.6	248.8
Fair Value, Recurring | Level 2 | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	94.7	124.2
Fair Value, Recurring | Level 2 | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 2 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0.2
Fair Value, Recurring | Level 2 | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0.5
Fair Value, Recurring | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivatives	0	0
Total assets	156	56.8
Derivatives	0
Total liabilities	0
Fair Value, Recurring | Level 3 | Fixed maturities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	36.4	50.4
Fair Value, Recurring | Level 3 | Fixed maturities | Collateralized Loan Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | U.S. Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Foreign Governments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Obligations of states and political subdivisions
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Corporate bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	22.7	32.6
Fair Value, Recurring | Level 3 | Fixed maturities | Commercial mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	0	0
Fair Value, Recurring | Level 3 | Fixed maturities | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	13.7	17.8
Fair Value, Recurring | Level 3 | Equity securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	81.9	6.4
Fair Value, Recurring | Level 3 | Other investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	37.7	0
Fair Value, Recurring | Level 3 | Short-term investments
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total investments	$ 0	$ 0

Investments - Schedule of Recon

Investments - Schedule of Reconciliation of Beginning and Ending Balances for Investments Categorized as Level 3 (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 56.8	$ 56.2
Transfers into Level 3	0.7	5.6
Transfers out of Level 3	(10.1)	(13.2)
Included in net income	29.5	(0.5)
Included in other comprehensive income	0	0.8
Purchases	98.9	10.6
Sales	0	(1.6)
Settlements	(19.8)	(1.1)
Ending balance	156	56.8
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at end of period	29.3	(0.8)
Fixed maturities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	50.4	40.7
Transfers into Level 3	0.7	5.6
Transfers out of Level 3	(10.1)	(5.6)
Included in net income	1.2	(0.1)
Included in other comprehensive income	0	0.8
Purchases	1.9	10.6
Sales	0	(0.5)
Settlements	(7.7)	(1.1)
Ending balance	36.4	50.4
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at end of period	0	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	6.4	15.5
Transfers into Level 3	0	0
Transfers out of Level 3	0	(7.6)
Included in net income	28.3	(0.4)
Included in other comprehensive income	0	0
Purchases	47.2	0
Sales	0	(1.1)
Settlements	0	0
Ending balance	81.9	6.4
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at end of period	29.3	(0.8)
Other Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0
Transfers into Level 3	0
Transfers out of Level 3	0
Included in net income	0
Included in other comprehensive income	0
Purchases	49.8
Sales	0
Settlements	(12.1)
Ending balance	37.7	$ 0
Amount of total gains or losses for the year included in net income attributable to the change in unrealized gains or losses relating to assets still held at end of period	$ 0

Investments - Schedule of Com_2

Investments - Schedule of Commercial Mortgage Loans (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost	$ 234.9	$ 144.8
Total Loans Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost	435.6	144.8
Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost	234.9	144.8
Private loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost	200.7	0
Fair Value | Total Loans Member
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost	442.1	148.8
Fair Value | Mortgage loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost	240.3	148.8
Fair Value | Private loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, at cost	$ 201.8	$ 0

Allowance for Credit Losses - S

Allowance for Credit Losses - Schedule of Premiums Receivable (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Credit Loss [Abstract]
Premiums receivable	$ 191.7	$ 269.7	$ 230.7	$ 292
Premium Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	3	4.7
Current period change for estimated uncollectible premiums	3	5.1
Write-offs of uncollectible premiums receivable	(1.8)	(2.4)
Ending balance	$ 4.2	$ 7.4

Allowance for Credit Losses -_2

Allowance for Credit Losses - Schedule of Reinsurance Recoverables (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Dec. 31, 2022
Credit Loss [Abstract]
Reinsurance Recoverables, Net of Allowance for Estimated Uncollectible Reinsurance	$ 3,130.7	$ 2,959.3	$ 2,889.6	$ 3,029.1
Allowance for Estimated Uncollectible Reinsurance	$ 0	$ 0	$ 4.7	$ 4.7

Reserves for Losses and Loss _3

Reserves for Losses and Loss Adjustment Expenses - Schedule of Reserves for Losses and Loss Adjustment Expenses (Details) $ in Millions	3 Months Ended		9 Months Ended		11 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Nov. 15, 2023 USD ($) agreement	Dec. 31, 2023 USD ($)
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Net reserves - beginning of the year			$ 2,747.1	$ 2,213.1	$ 2,213.1
Losses and LAE incurred during current calendar year, net of reinsurance:
Current accident year			583.8	680.9
Prior accident years			209.7	126
Losses and LAE incurred during calendar year, net of reinsurance	$ 346.8	$ 280.9	793.5	806.9
Losses and LAE payments made during current calendar year, net of reinsurance:
Current accident year			53.2	94.9
Prior accident years			552.6	361.6
Losses and LAE payments made during current calendar year, net of reinsurance:			605.8	456.5
Add/(Deduct):
Divestitures			0	24.4
Retroactive reinsurance			0	21.7
Deferred gain on U.S. loss portfolio transfer, net of amortization			0	(16.8)
Purchase accounting adjustment			19.4	0
Total net reserve adjustments			19.4	29.3
Foreign exchange adjustments			(1.6)	0.9
Net reserves - end of period	2,952.6	2,593.7	2,952.6	2,593.7
Reinsurance recoverables on unpaid losses and LAE, end of period	2,840.3	2,735	2,840.3	2,735
Gross reserves - end of period	$ 5,792.9	$ 5,328.7	$ 5,792.9	$ 5,328.7		$ 5,544.5
Number of retroactive reinsurance agreements entered into | agreement					2

Reserves for Losses and Loss _4

Reserves for Losses and Loss Adjustment Expenses - Schedule of Impact from (Favorable) Unfavorable Development of Prior Accident Years' Loss and LAE Reserves on Each Reporting Segment (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total unfavorable (favorable) prior-year development	$ 209.7	$ 126
U.S. Operations
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total unfavorable (favorable) prior-year development	125.1	111.7
International Operations
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total unfavorable (favorable) prior-year development	77.3	11.7
Run-off Lines
Schedule Of Prior Accident Years Loss And Loss Adjustment Expense Reserves Development [Line Items]
Total unfavorable (favorable) prior-year development	$ 7.3	$ 2.6

Disclosures About Fair Value _3

Disclosures About Fair Value of Financial Instruments - Schedule of Company's Financial Instruments Whose Carrying Amount Did Not Equal Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	$ 371.4	$ 369.2
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	388	381.9
Junior subordinated debentures | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	242.7	241.2
Junior subordinated debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	257.6	249.2
Junior subordinated debentures | Trust preferred debentures | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	161.7	160.8
Junior subordinated debentures | Trust preferred debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	172.7	165.9
Junior subordinated debentures | Subordinated debentures | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	81	80.4
Junior subordinated debentures | Subordinated debentures | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	84.9	83.3
Senior unsecured fixed rate notes | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	128.7	128
Senior unsecured fixed rate notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Financial instruments	$ 130.4	$ 132.7

Disclosures About Fair Value _4

Disclosures About Fair Value of Financial Instruments - Schedule of Fair Values Measured on Recurring Basis (Details) - Fair Value, Recurring - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	$ 388	$ 381.9
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	130.4	132.7
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	257.6	249.2
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	257.6	249.2
Junior subordinated debentures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	257.6	249.2
Junior subordinated debentures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Trust preferred debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	172.7	165.9
Junior subordinated debentures | Trust preferred debentures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Trust preferred debentures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	172.7	165.9
Junior subordinated debentures | Trust preferred debentures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Subordinated debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	84.9	83.3
Junior subordinated debentures | Subordinated debentures | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Junior subordinated debentures | Subordinated debentures | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	84.9	83.3
Junior subordinated debentures | Subordinated debentures | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Senior unsecured fixed rate notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	130.4	132.7
Senior unsecured fixed rate notes | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	130.4	132.7
Senior unsecured fixed rate notes | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	0	0
Senior unsecured fixed rate notes | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments	$ 0	$ 0

Stockholders' Equity (Details)

Stockholders' Equity (Details) $ / shares in Units, shares in Millions, $ in Millions			3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 16, 2024 USD ($)	Aug. 16, 2024 $ / shares	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) shares	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($)	May 07, 2024	Dec. 31, 2023 $ / shares
Class of Stock [Line Items]
Preferred stock, dividends declared (in dollars per share)			$ 437.50
Preferred stock, dividend rate (in percentage)		7%
Preferred shares par value (in dollars per share)		$ 1	1			$ 1			$ 1
Liquidation preference (in dollars per share)		$ 25,000	25,000			$ 25,000			$ 25,000
Fractional interest per one preference share								0.001
Depositary shares, dividends per share (in dollars per share)			$ 0.43750
Dividends declared | $	$ 2.6		$ 2.6	$ 2.6		$ 7.9	$ 7.9
Argo Group International Holdings, Inc. | Brookfield Reinsurance
Class of Stock [Line Items]
Number of shares purchased (in shares) | shares					200
Consideration transferred, equity interests issued | $					$ 200

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 1,297.5	$ 1,232.9
Other comprehensive income (loss) before reclassifications	20.6	1.4
Amounts reclassified from accumulated other comprehensive income (loss)	(3.8)	22.4
Net current-period other comprehensive income (loss)	16.8	23.8
Ending Balance	1,397.1	1,171.3
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	51.8	(305.1)
Ending Balance	68.6	(281.3)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	0.1	(4.2)
Other comprehensive income (loss) before reclassifications	0.3	1
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Net current-period other comprehensive income (loss)	0.3	1
Ending Balance	0.4	(3.2)
Unrealized Holding Gains (Losses) on Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	51.1	(293.1)
Other comprehensive income (loss) before reclassifications	20.3	(0.4)
Amounts reclassified from accumulated other comprehensive income (loss)	(3.8)	22.4
Net current-period other comprehensive income (loss)	16.5	22
Ending Balance	67.6	(271.1)
Defined Benefit Pension Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	0.6	(7.8)
Other comprehensive income (loss) before reclassifications	0	0.8
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Net current-period other comprehensive income (loss)	0	0.8
Ending Balance	$ 0.6	$ (7)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Schedule of Amounts Reclassified from Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Unrealized gains and losses on securities:
Net realized investment and other gains (losses)	$ (0.2)	$ (4.7)	$ 30.8	$ (21)
Income tax provision (benefit)	(34.4)	17.6	(27.2)	3.3
Net income (loss)	(132.3)	(46.9)	(94)	(78.5)
Reclassification out of Accumulated Other Comprehensive Income
Unrealized gains and losses on securities:
Net income (loss)	(1.3)	(1.9)	3.8	(22.4)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains and Losses on Securities
Unrealized gains and losses on securities:
Net realized investment and other gains (losses)	(1.6)	(1.5)	4.8	(27.4)
Income tax provision (benefit)	$ 0.3	$ (0.4)	$ (1)	$ 5

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Supplemental Cash Flow [Line Items]
Total interest paid	$ 27.5	$ 25
Income taxes paid	0.1	0.2
Income taxes recovered	(31.3)	(0.1)
Income taxes paid (recovered), net	(31.2)	0.1
Noncash activity for a lease commenced	3.3
Senior unsecured fixed rate notes
Supplemental Cash Flow [Line Items]
Total interest paid	7	7
Junior subordinated debentures
Supplemental Cash Flow [Line Items]
Total interest paid	18.6	17.2
Other indebtedness
Supplemental Cash Flow [Line Items]
Total interest paid	$ 1.9	$ 0.8

Underwriting, Acquisition and_3

Underwriting, Acquisition and General Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Underwriting, Acquisition and Insurance Expenses [Abstract]
Commission expense	$ 7.6	$ 46.6	$ 65.2	$ 144.5
Other underwriting and insurance expenses	62.6	74	195	230.2
Amortization of value of business acquired and other intangible assets	43	0	129.1	0
Total	113.2	120.6	389.3	374.7
Net deferral of policy acquisition costs	(2.3)	(4.5)	(44.5)	(10.7)
Total underwriting, acquisition and general expenses	$ 110.9	$ 116.1	$ 344.8	$ 364

Income Taxes - Schedule of Pre-

Income Taxes - Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (166.7)	$ (29.3)	$ (121.2)	$ (75.2)
Effective Tax Rate	20.60%	(60.10%)	22.50%	(4.40%)
Bermuda
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0	$ (9.8)	$ 0	$ (21.1)
Effective Tax Rate	0%	0%	0%	0%
United States
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (163.9)	$ (18.1)	$ (114.1)	$ (31.2)
Effective Tax Rate	21%	(95.50%)	23.90%	(32.90%)
United Kingdom
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (2.1)	$ (1.6)	$ (4.4)	$ (23.2)
Effective Tax Rate	0%	(22.50%)	0%	30.40%
Barbados
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0	$ 0.1	$ 0	$ 0.1
Effective Tax Rate	0%	0%	0%	0%
United Arab Emirates
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)			$ 0	$ 0.3
Effective Tax Rate			0%	0%
Ireland
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0	$ 0.1	$ 0	$ (0.1)
Effective Tax Rate	0%	0%	0%	0%
Italy
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (0.7)	$ 0.2	$ (2.7)	$ 0.1
Effective Tax Rate	0%	20%	(1.40%)	50.30%

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Difference Between Provision for Income Taxes and Expected Tax Provision at Weighted Average Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income tax provision (benefit) at expected rate	$ (35.1)	$ (4.1)	$ (25.7)	$ (11)
Tax effect of:
Nontaxable investment income	0	0	(0.2)	(0.1)
Foreign exchange adjustments	0	0	0	(2.6)
Base Erosion and Anti-Abuse Tax	0	20.4	0	16.9
Withholding taxes	0	0	0	0.1
Ireland Capital Loss	0	0	3.3	0
U.S. state tax expense, net of federal income tax effect	0	0	0	(1.2)
Change in uncertain tax position liability	0	0.2	0	1.2
Change in valuation allowance	0.3	0	(2.2)	0.1
Impact of change in tax rate related to Finance Act 2021	0	0	0	(0.4)
Prior period adjustment	(0.3)	0.2	(3.6)	0.1
Other	0.7	0.9	1.2	0.2
Income tax provision (benefit)	$ (34.4)	$ 17.6	$ (27.2)	$ 3.3

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Valuation Allowance [Line Items]
Net operating losses carryback period			2 years
Capital losses carryback period			3 years
Change in valuation allowance	$ 0.3	$ 0	$ (2.2)	$ 0.1
More-likely-than-not deferred tax assets that will be realized	65.9		65.9		$ 39.1
Decrease in tax penalty expense	0		1.1
Decrease in income tax penalties expense	$ 0		0.2
Revenue Commissioners, Ireland
Valuation Allowance [Line Items]
(Decrease) increase in valuation allowance			(3.3)
His Majesty's Revenue and Customs (HMRC)
Valuation Allowance [Line Items]
(Decrease) increase in valuation allowance			$ 1.1

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 16, 2023	Sep. 30, 2024
Other Commitments [Line Items]
Contractual commitments related to its limited partnership investments (up to)		$ 82.2
Commitment to fund loan and mortgage loans		$ 75.9
Argo Group International Holdings, Inc. | Common Stock | Brookfield Wealth Solutions Ltd
Other Commitments [Line Items]
Equity interests issued and issuable (in dollars per share)	$ 30

Segment Information - Additiona

Segment Information - Additional Information (Details)	9 Months Ended
	Sep. 30, 2024 segment
Segment Reporting [Abstract]
Number of reportable segments	2

Segment Information - Schedule

Segment Information - Schedule of Revenue and Income (Loss) Before Income Taxes for Each Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Net earned premiums	$ 234.3	$ 342.7	$ 837.9	$ 1,062.5
Net investment income	62.3	40.4	187.1	102.9
Net investment and other gains (losses)	(0.2)	(4.7)	30.8	(21)
Total revenue	296.4	378.4	1,055.8	1,144.4
Income (loss) before income taxes	(166.7)	(29.3)	(121.2)	(75.2)
Foreign currency exchange gains (losses)	3.8	3.3	3.1	(0.1)
Operating Segments
Segment Reporting Information [Line Items]
Income (loss) before income taxes	(173.1)	(16.6)	(149.5)	(14.9)
Corporate and Other
Segment Reporting Information [Line Items]
Income (loss) before income taxes	2.8	(11.3)	(5.6)	(39.2)
U.S. Operations | Operating Segments
Segment Reporting Information [Line Items]
Net earned premiums	210.4	314.1	761.9	950.9
Net investment income	52.3	33.2	158.4	84.7
Income (loss) before income taxes	(100.3)	(14)	(74.3)	(23.2)
International Operations | Operating Segments
Segment Reporting Information [Line Items]
Net earned premiums	23.9	28.5	75.8	111.4
Net investment income	7.6	6.2	22.8	15.8
Income (loss) before income taxes	(67.1)	(2.6)	(70.1)	9.3
Run-off Lines | Operating Segments
Segment Reporting Information [Line Items]
Net earned premiums	0	0.1	0.2	0.2
Net investment income	2.4	1	5.9	2.4
Income (loss) before income taxes	$ (5.7)	$ 0	$ (5.1)	$ (1)

Segment Information - Schedul_2

Segment Information - Schedule of Earned Premiums by Geographic Location (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	$ 234.3	$ 342.7	$ 837.9	$ 1,062.5
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	210.4	314.2	762.1	951.1
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	0	0	0	48.3
Bermuda
Revenues from External Customers and Long-Lived Assets [Line Items]
Total earned premiums	$ 23.9	$ 28.5	$ 75.8	$ 63.1

Segment Information - Schedul_3

Segment Information - Schedule of Identifiable Assets (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 8,816.6	$ 8,503.1
Operating Segments | U.S. Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	6,788.6	6,279
Operating Segments | International Operations
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	1,705.9	1,888.9
Operating Segments | Run-off Lines
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	215.7	221.4
Corporate and Other
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 106.4	$ 113.8

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Net investment and other gains (losses)	$ (0.2)	$ (4.7)	$ 30.8	$ (21)
Included in net income			29.5		$ (0.5)
Loans, at cost	234.9		234.9		144.8
Unfunded Commitments	112.6		112.6		93.4
Accrued underwriting expenses and other liabilities	109		109		73.9
Equity securities
Related Party Transaction [Line Items]
Included in net income			28.3		$ (0.4)
Related Party
Related Party Transaction [Line Items]
Purchase of loans	207		459.7
Net investment and other gains (losses)			27.9
Unfunded Commitments	55		55
Investment management fees	2.6		7.4
Accrued underwriting expenses and other liabilities	2.6		2.6
Related Party | Mortgage And Private Loans
Related Party Transaction [Line Items]
Loans, at cost	277.2		277.2
Related Party | Other Investments
Related Party Transaction [Line Items]
Loans, at cost	$ 138.6		$ 138.6