Reserves for Losses and Loss Adjustment Expenses (Tables)

12 Months Ended

Dec. 31, 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
	For the Year Ended		Period from		Period from		For the Year Ended
(in millions)	December 31, 2024		November 16, 2023 through December 31, 2023		January 1, 2023 through November 15, 2023		December 31, 2022
Net reserves beginning of the period	$	2,747.1	$	2,734.6	$	2,213.1	$	3,123.2
Add:
Losses and LAE incurred during current calendar year, net of reinsurance:
Current accident year	763.4		94.2		775.3		1,102.2
Prior accident years	254.9		—		267.9		64.7
Losses and LAE incurred during calendar year, net of reinsurance	1,018.3		94.2		1,043.2		1,166.9
Deduct:
Losses and LAE payments made during current calendar year, net of reinsurance:
Current accident year	91.4		33.5		100.6		171.5
Prior accident years	687.0		51.8		427.3		828.0
Losses and LAE payments made during current calendar year, net of reinsurance:	778.4		85.3		527.9		999.5
Add/(Deduct):
Divestitures (1)	—		—		24.4		(35.2)
Reclassified to liabilities held-for-sale (2)	—		—		—		(313.0)
Net reserves ceded to Syndicate 1200 (2)	—		—		—		(129.6)
Deferred gain on U.S. loss portfolio transfer, net of amortization	—		—		(40.9)		—
Loss portfolio transfer:
U.S. (3)	—		—		—		(472.6)
Syndicate 1200 (for years of account 2018 and 2019) (4)	—		—		—		(144.0)
Retroactive reinsurance (5)	—		—		21.7		—
Change in participation interest (6)	—		—		—		34.3
Purchase accounting adjustment (7)	19.4		—		—		—
Total net reserve adjustments	19.4		—		5.2		(1,060.1)
Foreign exchange adjustments	(2.5)		3.6		1.0		(17.4)
Net reserves - end of period	3,003.9		2,747.1		2,734.6		2,213.1
Add:
Reinsurance recoverables on unpaid losses and LAE, end of year	2,794.7		2,797.4		2,791.8		2,838.5
Gross reserves - end of period	$	5,798.6	$	5,544.5	$	5,526.4	$	5,051.6

(1)For the period ended November 15, 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 2, “Recent Acquisitions, Disposals & Other Transactions” in our 2023 Form 10-K for additional information. For the period ended December 31, 2022, refer to the sale of Argo Seguros and AGSE in Note 2, “Recent Acquisitions, Disposals & Other Transactions” in our 2023 Form 10-K for additional information.

(2)Refer to the sale of Argo Underwriting Agency Limited in Note 2, “Recent Acquisitions, Disposals & Other Transactions” in our 2023 Form 10-K for additional information. Additionally, the Company reduced net reserves in the amount of $129.6 million for reinsurance contracts with AUA subsidiaries, which were reclassified to held-for-sale.

(3)Loss portfolio transfer of the Company’s U.S. casualty insurance reserves for accident years 2011 to 2019. Refer to Note 2, “Recent Acquisitions, Disposals & Other Transactions” in our 2023 Form 10-K for additional information.

(4)Loss portfolio transfer on Syndicate 1200's reserves for the 2018 and 2019 years of account. Refer to Note 2, “Recent Acquisitions, Disposals & Other Transactions” in our 2023 Form 10-K for additional information.

(5)In connection with the sale of AUA, the Company entered into two retroactive reinsurance agreements with AUA subsidiaries.

(6)Amount represents the change in reserves due to changing our participation in Syndicates 1200 and 1910.

(7)Impact of measurement period adjustment in connection with the Merger. Refer to Note 2, “Recent Acquisitions, Disposals & Other Transactions” 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 net unfavorable (favorable) development of prior accident years’ losses and LAE reserves on each reporting segment is presented below: 

	Successor
	For the Year Ended		Period from
(in millions)	December 31, 2024		November 16, 2023 through December 31, 2023
Casualty Lines	$	87.7	$	—
Specialty Lines	3.1		—
Run-off Lines	164.1		—
Total (favorable) unfavorable prior-year development	$	254.9	$	—

	Predecessor
	Period from		For the Year Ended
(in millions)	January 1, 2023 through November 15, 2023		December 31, 2022
U.S. Operations	$	246.3	$	64.5
International Operations	21.4		(2.7)
Run-off Lines	0.2		2.9
Total (favorable) unfavorable prior-year development	$	267.9	$	64.7

Schedule of Information About Incurred and Cumulative Paid Losses and Allocated Loss Adjustment Expenses, Net of Reinsurance

The following tables provide information about incurred and cumulative paid losses and allocated loss adjustment expenses (“ALAE”), net of reinsurance. The following tables also include IBNR reserves plus expected development on reported claims and the cumulative number of reported claims as of December 31, 2024.

Reporting Segment: Casualty Lines (in millions, except number of claims reported)
	Incurred Losses & ALAE, Net of Reinsurance
Accident Year	For the Years Ended December 31,
		2015 (1)		2016 (1)		2017 (1)		2018 (1)		2019 (1)		2020 (1)		2021 (1)		2022 (1)		2023 (1)		2024 (1)
2015		$	186.8	$	186.8	$	187.3	$	194.1	$	191.2	$	198.4	$	212.1	$	158.7	$	185.3	$	202.2
2016				205.6		204.9		191.6		179.6		178.7		184.5		162.4		157.1		159.4
2017						228.1		227.0		231.7		233.9		257.5		147.6		216.1		225.2
2018								253.4		261.2		245.9		241.3		194.3		174.4		190.3
2019										248.1		243.5		233.5		359.3		144.2		143.4
2020												235.4		213.3		190.2		203.3		233.2
2021														257.1		243.7		247.6		255.8
2022																306.7		302.4		300.4
2023																		332.8		328.5
2024																				331.4
																		Total		$	2,369.8
	Cumulative Paid Losses & ALAE, Net of Reinsurance
Accident Year	For the Years Ended December 31,
		2015 (1)		2016 (1)		2017 (1)		2018 (1)		2019 (1)		2020 (1)		2021 (1)		2022 (1)		2023 (1)		2024 (1)
2015		$	11.7	$	30.7	$	70.5	$	98.2	$	119.4	$	141.4	$	161.4	$	174.3	$	174.9	$	175.6
2016				12.3		33.4		58.3		91.7		110.8		128.9		131.7		132.6		137.1
2017						12.7		43.4		72.8		124.6		158.4		164.3		171.8		188.6
2018								16.2		58.6		100.7		130		140.6		146.3		148.6
2019										15.2		49.9		80.1		90.5		97.9		101.9
2020												13.3		33.9		54.4		79.9		116.8
2021														13.1		37.4		70.3		104.3
2022																12.9		42.4		72.9
2023																		13.8		51.8
2024																				12.9
																		Total		1,110.5
Other Casualty outstanding liabilities including unpaid loss and ALAE prior to 2014, net of reinsurance																				54.2
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance																				$	1,313.5

	As of December 31, 2024
Accident Year	Incurred Losses & ALAE, Net of Reinsurance		IBNR & Expected Development on Reported Claims		Cumulative Number of Reported Claims (2)
2015	$	202.2	$	14.9	5,764
2016	159.4		16.1		5,853
2017	225.2		30.1		8,831
2018	190.3		30.9		9,352
2019	143.4		21.6		9,210
2020	233.2		62.7		7,137
2021	255.8		103.8		7,591
2022	300.4		181.6		7,728
2023	328.5		238.1		6,341
2024	331.4		289.3		4,989

(1)Information presented for calendar years prior to 2024 is required supplementary information and is unaudited.

(2)During 2021, the Company revised the manner in which it measures reported claims. The cumulative number of reported claims is measured by individual claimant at a coverage level. Reported occurrences that do not result in a liability are included as reported claims. During 2021, we implemented additional processes to consolidate multiple data sources for U.S. Operations reserving. As part of that process, the level of detail used to determine the number of reported claims for some of the business units in U.S. Operations changed. As a result, the cumulative number of reported claims for each accident year presented above as of December 31, 2021 is not comparable to the cumulative number of reported claims disclosed in previously issued financial statements.

Reporting Segment: Specialty Lines (in millions, except number of claims reported)
	Incurred Losses & ALAE, Net of Reinsurance
Accident Year	For the Years Ended December 31,
	2015 (1)		2016 (1)		2017 (1)		2018 (1)		2019 (1)		2020 (1)		2021 (1)		2022 (1)		2023 (1)		2024 (1)
2015	$	49.2	$	50.8	$	45.9	$	47.5	$	47.8	$	47.4	$	47.5	$	45.0	$	45.0	$	45.4
2016			40.6		41.0		41.2		44.9		43.7		43.4		42.2		41.7		41.8
2017					64.2		66.0		67.8		73.0		75.4		70.9		67.3		67.6
2018							91.8		94.0		91.5		95.7		87.9		84.6		86.2
2019									104.9		98.4		96.0		83.6		85.4		86.5
2020											98.3		106.5		135.0		144.7		143.3
2021													127.7		149.9		150.1		152.5
2022															191.0		193.6		198.3
2023																	170.5		155.5
2024																			155.4
																	Total		$	1,132.5
	Cumulative Paid Losses & ALAE, Net of Reinsurance
Accident Year	For the Years Ended December 31,
	2015 (1)		2016 (1)		2017 (1)		2018 (1)		2019 (1)		2020 (1)		2021 (1)		2022 (1)		2023 (1)		2024 (1)
2015	$	19.4	$	31.7	$	36.9	$	42.6	$	44.6	$	45.8	$	45.9	$	45.3	$	45.4	$	46.1
2016			18.8		28.5		34.6		39.7		41.1		42.1		40.2		40.5		40.5
2017					24.4		37.6		49.3		58.6		65.0		65.9		66.7		67.6
2018							32.0		51.0		62.7		73.3		78.4		80.2		82.4
2019									30.9		51.6		64.3		75.1		79.1		82.1
2020											31.0		62.9		93.1		106.9		117.4
2021													33.8		84.1		96.8		111.2
2022															51.8		103.0		128.4
2023																	56.2		98.1
2024																			43.2
																	Total		817.0
Other Specialty outstanding liabilities including unpaid loss and ALAE prior to 2014, net of reinsurance																			(6.2)
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance																			$	309.3

	As of December 31, 2024
Accident Year	Incurred Losses & ALAE, Net of Reinsurance		IBNR & Expected Development on Reported Claims		Cumulative Number of Reported Claims (2)
2015	$	45.4	$	(0.8)	3,354
2016	41.8		1.2		4,559
2017	67.6		—		7,835
2018	86.2		3.7		8,398
2019	86.5		3.0		9,194
2020	143.3		12.9		9,094
2021	152.5		28.4		9,903
2022	198.3		47.7		9,248
2023	155.5		35.8		8,417
2024	155.4		79.5		6,487

(1)Information presented for calendar years prior to 2024 is required supplementary information and is unaudited.

(2)During 2021, the Company revised the manner in which it measures reported claims. The cumulative number of reported claims is measured by individual claimant at a coverage level. Reported occurrences that do not result in a liability are included as reported claims. During 2021, we implemented additional processes to consolidate multiple data sources for U.S. Operations reserving. As part of that process, the level of detail used to determine the number of reported claims for some of the business units in U.S. Operations changed. As a result, the cumulative number of reported claims for each accident year presented above as of December 31, 2021 is not comparable to the cumulative number of reported claims disclosed in previously issued financial statements.

Reporting Segment: Run-off Lines (in millions, except number of claims reported)
	Incurred Losses & ALAE, Net of Reinsurance
Accident Year	For the Years Ended December 31,
	2015 (1)		2016 (1)		2017 (1)		2018 (1)		2019 (1)		2020 (1)		2021 (1)		2022 (1)		2023 (1)		2024 (1)
2015	$	402.4	$	403.5	$	399.4	$	397.0	$	408.8	$	412.4	$	420.4	$	393.1	$	391.7	$	390.8
2016			440.8		442.6		459.0		458.3		457.0		471.6		444.9		448.9		449.8
2017					525.4		493.1		523.9		546.9		575.7		539.8		533.0		528.8
2018							460.2		563.3		556.0		578.9		584.6		599.6		609.5
2019									429.2		497.7		537.8		414.1		425.3		449.9
2020											461.0		448.1		403.5		474.7		516.6
2021													396.8		342.1		374.6		417.1
2022															288.1		303.9		317.1
2023																	281.6		314.8
2024																			238.4
																	Total		$	4,232.8
	Cumulative Paid Losses & ALAE, Net of Reinsurance
Accident Year	For the Years Ended December 31,
	2015 (1)		2016 (1)		2017 (1)		2018 (1)		2019 (1)		2020 (1)		2021 (1)		2022 (1)		2023 (1)		2024 (1)
2015	$	83.3	$	146.3	$	211.3	$	272.0	$	306.4	$	325.6	$	385.9	$	386.0	$	385.2	$	388.8
2016			94.1		113.7		275.9		353.1		374.2		428.0		430.2		436.0		432.0
2017					200.7		250.9		364.8		432.7		492.3		508.2		504.9		523.5
2018							104.0		298.2		366.4		430.3		493.7		510.2		552.8
2019									102.6		264.4		305.1		331.4		356.0		380.1
2020											186.0		194.6		248.5		312.0		374.7
2021													72.0		125.6		177.2		248.2
2022															30.0		82.2		114.2
2023																	20.5		93.4
2024																			27.7
																	Total		3,135.4
Other Runoff outstanding liabilities including unpaid loss and ALAE prior to 2014, net of reinsurance																			168.7
Total outstanding liabilities for unpaid losses and ALAE, net of reinsurance																			$	1,266.1

	As of December 31, 2024
Accident Year	Incurred Losses & ALAE, Net of Reinsurance		IBNR & Expected Development on Reported Claims		Cumulative Number of Reported Claims (2)
2015	$	390.8	$	0.7	21,158
2016	449.8		15.6		19,828
2017	528.8		6.8		21,751
2018	609.5		47.9		23,784
2019	449.9		55.6		23,774
2020	516.6		68.8		22,592
2021	417.1		115.1		18,914
2022	317.1		132.9		17,526
2023	314.8		189.5		13,258
2024	238.4		152.1		9,260

(1)Information presented for calendar years prior to 2024 is required supplementary information and is unaudited.

(2)During 2021, the Company revised the manner in which it measures reported claims. The cumulative number of reported claims is measured by individual claimant at a coverage level. Reported occurrences that do not result in a liability are included as reported claims. During 2021, we implemented additional processes to consolidate multiple data sources for U.S. Operations reserving. As part of that process, the level of detail used to determine the number of reported claims for some of the business units in U.S. Operations changed. As a result, the cumulative number of reported claims for each accident year presented above as of December 31, 2021 is not comparable to the cumulative number of reported claims disclosed in previously issued financial statements.

Schedule of Reconciliation of Net Incurred and Paid Development to Liability for Unpaid Losses and LAE in Consolidated Balance Sheets

The reconciliation of the net incurred and paid development tables to the liability for unpaid losses and LAE in our Consolidated Balance Sheets is as follows:

(in millions)	As of December 31, 2024
Liabilities for unpaid losses and ALAE:
Casualty Lines	$	1,313.5
Specialty Lines	309.3
Run-off Lines	1,266.1
Other lines	68.7
Total liabilities for unpaid losses and ALAE, net of reinsurance	2,957.6
Reinsurance recoverables on unpaid losses and LAE:
Casualty Lines	1,046.0
Specialty Lines	214.3
Run-off Lines	1,042.2
Other lines	492.2
Total reinsurance recoverables on unpaid losses and LAE	2,794.7
Unallocated LAE	68.3
Unamortized reserve discount	(22.0)
Gross liability for unpaid losses and LAE	$	5,798.6

Schedule of Supplementary Unaudited Information About Annual Percentage Payout of Incurred Losses and ALAE, Net of Reinsurance

The following table provides supplementary unaudited information about the annual percentage payout of incurred losses and ALAE, net of reinsurance, as of December 31, 2024:

	Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance (1)
	Year 1	Year 2	Year 3	Year 4	Year 5	Year 6	Year 7	Year 8	Year 9	Year 10	Remainder
Casualty Lines	2.8%	8.2%	12.5%	14.9%	14.0%	11.0%	11.1%	7.4%	5.4%	3.9%	8.8%
Specialty Lines	30.4%	24.3%	14.2%	8.5%	8.1%	5.1%	3.1%	2.0%	1.4%	0.9%	2.0%
Run-off Lines	15.0%	18.0%	14.8%	13.1%	11.1%	8.8%	5.4%	3.9%	2.8%	2.0%	5.1%

(1) The average annual percentage payout is calculated from a paid losses and ALAE development pattern based on an actuarial analysis of the paid losses and ALAE movements by accident year for each disaggregation category. The paid losses and ALAE development pattern provides the expected percentage of ultimate losses and ALAE to be paid in each year. The pattern considers all accident years included in the claims development tables.

Schedule of Information About Discounted Liabilities for Unpaid Losses and LAE

The following tables provide information about these discounted liabilities for unpaid losses and LAE:

	Carrying Amount of
	Reserves for Losses & LAE						Aggregate Amount of Discount
	As of December 31,						As of December 31,
(in millions, except discount percentages)	2024		2023		2022		2024		2023		2022
Casualty Lines	$	197.1	$	182.6	$	168.0	$	17.4	$	16.1	$	14.7
Run-off Lines	81.9		76.8		93.0		4.6		4.7		4.6
Total	$	279.0	$	259.4	$	261.0	$	22.0	$	20.8	$	19.3

	Interest Accretion (1)								Discount Rate
	Successor				Predecessor
	For the Year Ended		Period from		Period from		For the Year Ended		As of December 31,
	December 31, 2024		November 16, 2023 through December 31, 2023		January 1, 2023 through November 15, 2023		December 31, 2022		2024	2023	2022
Casualty Lines	$	1.5	$	0.1	$	1.3	$	1.7	2.25%	2.25%	2.25%
Run-off Lines	0.1		—		0.1		0.1		3.50%	3.50%	3.50%
Total	$	1.6	$	0.1	$	1.4	$	1.8

(1) Interest accretion is recorded in the line item Losses and loss adjustment expenses in our Consolidated Statements of Income (Loss).