Unpaid losses and loss expenses (Tables)

12 Months Ended

Dec. 31, 2023

Liability for Claims and Claims Adjustment Expense [Abstract]

Schedule Of Unpaid Losses And Loss Expenses Roll Forward

Chubb establishes reserves for the estimated unpaid ultimate liability for losses and loss expenses under the terms of its policies and agreements. Reserves include estimates for both claims that have been reported and for IBNR claims, and include estimates of expenses associated with processing and settling these claims. Reserves are recorded in Unpaid losses and loss expenses in the Consolidated balance sheets. While we believe that our reserves for unpaid losses and loss expenses at December 31, 2023, are adequate, new information or trends may lead to future developments in incurred loss and loss expenses significantly greater or less than the reserves provided. Any such revisions could result in future changes in estimates of losses or reinsurance recoverable and would be reflected in our results of operations in the period in which the estimates are changed.

The following table presents a reconciliation of beginning and ending Unpaid losses and loss expenses:

	Year Ended December 31
(in millions of U.S. dollars)	2023		2022		2021
Gross unpaid losses and loss expenses, beginning of year	$	75,747	$	72,330	$	67,192
Reinsurance recoverable on unpaid losses (1)	(17,086)		(16,132)		(14,576)
Net unpaid losses and loss expenses, beginning of year	58,661		56,198		52,616
Net losses and loss expenses incurred in respect of losses occurring in:
Current year	24,956		23,680		21,986
Prior years (2)	(856)		(1,108)		(956)
Total	24,100		22,572		21,030
Net losses and loss expenses paid in respect of losses occurring in:
Current year	8,248		7,331		6,900
Prior years	12,763		12,206		10,048
Total	21,011		19,537		16,948
Consolidation of Huatai Group	405		—		—
Foreign currency revaluation and other	83		(572)		(500)
Net unpaid losses and loss expenses, end of year	62,238		58,661		56,198
Reinsurance recoverable on unpaid losses (1)	17,884		17,086		16,132
Gross unpaid losses and loss expenses, end of year	$	80,122	$	75,747	$	72,330

(1)     Net of valuation allowance for uncollectible reinsurance.

(2)    Relates to prior period loss reserve development only and excludes prior period development related to reinstatement premiums, expense adjustments, earned premiums, and A&H long-duration lines totaling $83 million, $232 million, and $30 million for 2023, 2022, and 2021, respectively.

Reconciliation of Claims Development to Liability [Table Text Block]

The following table presents a reconciliation of the loss development tables to the liability for unpaid losses and loss expenses in the consolidated balance sheet:

Reconciliation of Reserve Balances to Liability for Unpaid Loss and Loss Expenses
(in millions of U.S. dollars)	December 31, 2023
Presented in the loss development tables:
North America Commercial P&C Insurance — Workers' Compensation	$	10,159
North America Commercial P&C Insurance — Liability	21,092
North America Commercial P&C Insurance — Other Casualty	2,596
North America Commercial P&C Insurance — Non-Casualty	3,203
North America Personal P&C Insurance	3,550
Overseas General Insurance — Casualty	8,157
Overseas General Insurance — Non-Casualty	3,515
Global Reinsurance — Casualty	1,240
Global Reinsurance — Non-Casualty	411
Excluded from the loss development tables:
Other	6,286
Net unpaid loss and allocated loss adjustment expense	60,209
Ceded unpaid loss and allocated loss adjustment expense:
North America Commercial P&C Insurance — Workers' Compensation	1,190
North America Commercial P&C Insurance — Liability	7,427
North America Commercial P&C Insurance — Other Casualty	1,064
North America Commercial P&C Insurance — Non-Casualty	1,673
North America Personal P&C Insurance	577
Overseas General Insurance — Casualty	2,527
Overseas General Insurance — Non-Casualty	1,736
Global Reinsurance — Casualty	80
Global Reinsurance — Non-Casualty	101
Other	1,781
Ceded unpaid loss and allocated loss adjustment expense	18,156
Unpaid unallocated loss adjustment expenses	1,757
Unpaid losses and loss expenses	$	80,122

Claims Development tables [Table Text Block]

North America Commercial P&C Insurance — Workers' Compensation — Long-tail

This product line has a broad mix of exposures across industries as well as a mix of policy coverages. Types of coverage include risk management business predominantly with high deductible policies, loss sensitive business (i.e., retrospectively-rated policies), business fronted for captives, as well as excess and primary guaranteed cost coverages.

The triangle below shows all loss and allocated expense development for the workers' compensation product line. In our prior period development disclosure, we exclude any loss development where there is a directly related premium adjustment. For workers' compensation, changes in the exposure base due to payroll audits will drive changes in ultimate losses. In addition, we record involuntary pool assumptions (premiums and losses) on a lagged basis. Both of these items will influence the development in the triangle, particularly the first prior accident year, and are included in the reconciliation table presented on page F-66.

Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31 2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves		Reported Claims (in thousands)
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	1,207	$	1,201		$	1,217	$	1,215	$	1,163	$	1,100	$	1,073	$	1,037	$	1,007	$	983	$	236	45
2015			1,282			1,259		1,276		1,279		1,217		1,154		1,128		1,092		1,057		286		50
2016						1,366		1,361		1,383		1,378		1,269		1,206		1,177		1,162		354		51
2017								1,412		1,380		1,399		1,393		1,376		1,176		1,121		402		50
2018										1,359		1,361		1,380		1,385		1,384		1,221		435		51
2019												1,391		1,384		1,400		1,409		1,406		611		48
2020														1,367		1,388		1,409		1,408		756		31
2021																1,348		1,330		1,372		708		35
2022																		1,344		1,407		835		38
2023																				1,371		992		33
Total																				$	12,508

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	113	$	295		$	410	$	484	$	532	$	566	$	599	$	617	$	634	$	649
2015			116			301		418		501		564		606		628		645		665
2016						122		326		452		529		584		621		653		683
2017								120		313		437		516		564		601		626
2018										130		329		451		528		597		641
2019												143		341		467		575		640
2020														111		282		390		466
2021																120		331		458
2022																		131		332
2023																				129
Total																				$	5,289

Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	2,940
Accident years 2014 - 2023 from tables above	7,219
All Accident years	$	10,159

North America Commercial P&C Insurance — Liability — Long-tail

This line consists of primary and excess general liability exposures, medical liability, and professional lines, including directors and officers (D&O) liability, errors and omissions (E&O) liability, employment practices liability (EPL), fidelity bonds, and fiduciary liability.

The primary and excess general liability business represents the largest part of these exposures. The former includes both monoline and commercial package liability. The latter includes a substantial proportion of commercial umbrella, excess and high excess business, where loss activity can produce significant volatility in the loss triangles at later ages within an accident year (and sometimes across years) due to the size of the limits afforded and the complex nature of the underlying losses.

This line includes management and professional liability products provided to a wide variety of clients, from national accounts to small firms along with private and not-for-profit organizations, distributed through brokers, agents, wholesalers, and MGAs. Many of these coverages, particularly D&O and E&O, are typically written on a claims-made form. While most of the coverages are underwritten on a primary basis, there are significant amounts of excess exposure with large policy limits.

Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31 2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves		Reported Claims (in thousands)
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	3,528	$	3,578		$	3,667	$	3,710	$	3,649	$	3,463	$	3,340	$	3,192	$	3,142	$	3,134	$	237	24
2015			3,552			3,701		3,810		3,967		3,934		3,727		3,701		3,569		3,613		358		27
2016						3,527		3,588		3,685		3,797		3,793		3,765		3,756		3,660		375		27
2017								3,316		3,491		3,573		3,623		3,545		3,434		3,492		603		26
2018										3,368		3,485		3,688		3,820		3,900		3,915		672		28
2019												3,446		3,620		3,858		4,050		4,057		1,135		29
2020														4,102		3,826		3,919		3,976		1,630		24
2021																4,315		4,349		4,441		2,589		25
2022																		4,561		4,567		3,371		25
2023																				4,703		4,181		26
Total																				$	39,558

North America Commercial P&C Insurance — Liability — Long-tail (continued)
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	164	$	679		$	1,248	$	1,801	$	2,199	$	2,439	$	2,580	$	2,669	$	2,753	$	2,802
2015			138			604		1,203		1,852		2,287		2,527		2,743		2,921		3,079
2016						171		662		1,334		1,973		2,332		2,593		2,820		2,982
2017								161		616		1,160		1,698		2,000		2,322		2,627
2018										189		753		1,301		1,773		2,335		2,782
2019												175		669		1,245		1,888		2,387
2020														152		589		1,148		1,697
2021																174		609		1,200
2022																		144		649
2023																				197
Total																				$	20,402

Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	1,936
Accident years 2014 - 2023 from tables above	19,156
All Accident years	$	21,092

This product line consists of the remaining commercial casualty coverages such as automobile liability and aviation as well as our foreign casualty exposures (mainly auto, general liability and employer responsibility coverages) on U.S.-based multinational accounts. The paid and reported data are impacted by some catastrophe loss activity.

Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31 2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves		Reported Claims (in thousands)
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	594	$	582		$	580	$	595	$	554	$	538	$	538	$	530	$	526	$	530	$	9	17
2015			486			469		500		514		457		454		462		457		456		18		15
2016						503		501		527		523		480		479		469		473		20		16
2017								531		565		577		616		604		590		602		16		17
2018										535		563		574		579		575		606		9		17
2019												606		636		686		744		756		40		17
2020														640		633		657		638		156		11
2021																675		710		747		254		13
2022																		782		801		367		14
2023																				844		631		11
Total																				$	6,453

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	80	$	220		$	317	$	391	$	454	$	473	$	500	$	508	$	513	$	517
2015			47			137		214		304		370		394		411		423		431
2016						52		145		246		323		374		398		424		437
2017								66		175		312		381		446		496		539
2018										74		169		270		365		472		532
2019												70		189		318		465		619
2020														54		156		273		401
2021																60		176		293
2022																		82		235
2023																				81
Total																				$	4,085

Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	228
Accident years 2014 - 2023 from tables above	2,368
All Accident years	$	2,596

This product line represents first party commercial product lines that are short-tailed in nature, such as property, inland marine, ocean marine, surety, and A&H. There is a wide diversity of products, primary and excess coverages, and policy sizes. During this ten-year period, this product line was impacted by natural catastrophes mainly in the 2017 and 2018 accident years, and in accident year 2020 by direct COVID.

Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31 2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves		Reported Claims (in thousands)
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	1,635	$	1,655		$	1,573	$	1,552	$	1,543	$	1,544	$	1,552	$	1,545	$	1,544	$	1,554	$	—	483
2015			1,731			1,740		1,645		1,633		1,600		1,585		1,587		1,592		1,589		2		545
2016						1,904		1,884		1,794		1,775		1,811		1,824		1,820		1,822		23		650
2017								2,699		2,603		2,503		2,520		2,512		2,522		2,508		43		764
2018										2,047		2,234		2,169		2,161		2,170		2,160		11		904
2019												2,046		2,031		1,954		1,944		1,921		13		1,044
2020														3,140		2,942		2,726		2,685		62		1,126
2021																2,941		2,824		2,628		158		863
2022																		3,048		2,946		371		897
2023																				3,072		1,351		756
Total																				$	22,885

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	816	$	1,368		$	1,478	$	1,499	$	1,525	$	1,540	$	1,547	$	1,552	$	1,552	$	1,551
2015			724			1,339		1,484		1,552		1,567		1,570		1,583		1,582		1,583
2016						844		1,499		1,650		1,726		1,754		1,778		1,789		1,790
2017								977		2,083		2,301		2,392		2,406		2,430		2,449
2018										1,025		1,821		2,012		2,068		2,113		2,137
2019												1,028		1,672		1,800		1,856		1,883
2020														1,390		2,260		2,466		2,545
2021																1,085		2,100		2,322
2022																		1,050		2,190
2023																				1,219
Total																				$	19,669

North America Commercial P&C Insurance — Non-Casualty — Short-tail (continued)
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	(13)
Accident years 2014 - 2023 from tables above	3,216
All Accident years	$	3,203

North America Personal P&C Insurance — Short-tail

Chubb provides personal lines coverages for high-net-worth individuals and families in North America including homeowners, automobile, valuable articles (including fine art), umbrella liability, and recreational marine insurance offered through independent regional agents and brokers. During this ten-year period, this segment was also impacted by natural catastrophes, mainly in the 2017 and 2018 accident years.

Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31 2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves		Reported Claims (in thousands)
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	2,198	$	2,199		$	2,186	$	2,139	$	2,153	$	2,140	$	2,135	$	2,134	$	2,133	$	2,130	$	6	144
2015			2,488			2,543		2,553		2,536		2,556		2,562		2,559		2,561		2,558		5		148
2016						2,433		2,529		2,538		2,476		2,464		2,458		2,466		2,467		10		154
2017								3,028		3,062		2,995		2,991		2,992		3,001		3,011		20		163
2018										3,002		3,030		3,095		3,110		3,131		3,120		45		170
2019												2,949		2,985		2,986		2,978		2,957		48		157
2020														2,922		2,627		2,626		2,582		96		123
2021																3,027		2,877		2,964		209		131
2022																		3,102		2,955		414		119
2023																				3,406		1,480		93
Total																				$	28,150

North America Personal P&C Insurance — Short-tail (continued)
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	1,306	$	1,759		$	1,919	$	2,028	$	2,073	$	2,100	$	2,109	$	2,116	$	2,119	$	2,121
2015			1,495			2,078		2,264		2,385		2,472		2,501		2,526		2,535		2,542
2016						1,449		2,046		2,205		2,308		2,364		2,391		2,422		2,440
2017								1,694		2,514		2,662		2,793		2,864		2,930		2,971
2018										1,922		2,542		2,699		2,857		2,971		3,037
2019												1,664		2,431		2,611		2,718		2,823
2020														1,331		1,990		2,223		2,363
2021																1,583		2,368		2,582
2022																		1,411		2,278
2023																				1,490
Total																				$	24,647

Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	47
Accident years 2014 - 2023 from tables above	3,503
All Accident years	$	3,550

This product line comprises D&O liability, E&O liability, financial institutions (including crime/fidelity coverages), and non-U.S. general liability as well as aviation and political risk. Exposures are located around the world, including Europe, Latin America, and Asia. Approximately 46 percent of Chubb Overseas General business is generated by European accounts, exclusive of Lloyd's market. There is some U.S. exposure in Casualty from multinational accounts and in financial lines for Lloyd's market. The financial lines coverages are typically written on a claims-made form, while general liability coverages are typically on an occurrence basis and comprises a mix of primary and excess businesses.

Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31 2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves		Reported Claims (in thousands)
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	1,196	$	1,264		$	1,271	$	1,290	$	1,210	$	1,129	$	1,093	$	1,103	$	1,106	$	1,089	$	46	38
2015			1,118			1,209		1,239		1,262		1,244		1,186		1,171		1,187		1,186		97		40
2016						1,150		1,246		1,311		1,338		1,328		1,337		1,271		1,283		93		42
2017								1,140		1,237		1,284		1,331		1,296		1,331		1,296		151		43
2018										1,236		1,286		1,346		1,389		1,345		1,323		202		44
2019												1,307		1,373		1,395		1,382		1,336		311		42
2020														1,684		1,606		1,523		1,535		765		35
2021																1,619		1,668		1,691		987		36
2022																		1,760		1,808		1,217		36
2023																				1,908		1,606		32
Total																				$	14,455

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	105	$	275		$	444	$	571	$	681	$	761	$	823	$	865	$	894	$	934
2015			80			267		465		637		753		830		906		938		969
2016						120		306		505		648		766		857		979		1,003
2017								91		299		499		653		812		940		995
2018										105		312		470		608		727		881
2019												118		316		444		648		729
2020														102		273		429		530
2021																111		271		434
2022																		83		284
2023																				79
Total																				$	6,838

Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	540
Accident years 2014 - 2023 from tables above	7,617
All Accident years	$	8,157

This product line is comprised of commercial fire, marine (predominantly cargo), surety, personal automobile (in Latin America, Asia Pacific and Japan), personal cell phones, personal residential (including high net worth), energy, and construction. In general, these lines have relatively stable payment and reporting patterns although they are impacted by natural catastrophes mainly in the 2017, 2018, and 2022 accident years. For the Chubb Overseas General non-casualty book, Europe, exclusive of Lloyd's market, makes up about one third, Latin America makes up about one quarter, and Asia makes up about one fifth.

Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31 2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves		Reported Claims (in thousands)
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	1,764	$	1,828		$	1,775	$	1,763	$	1,729	$	1,719	$	1,712	$	1,706	$	1,698	$	1,693	$	3	533
2015			1,855			1,973		1,947		1,916		1,900		1,892		1,874		1,875		1,870		8		556
2016						1,959		1,955		1,942		1,921		1,926		1,957		1,955		1,943		29		568
2017								2,114		2,157		2,145		2,126		2,151		2,149		2,115		(6)		577
2018										2,068		2,156		2,119		2,093		2,062		2,051		42		613
2019												2,100		2,119		2,059		2,047		2,043		(12)		632
2020														2,437		2,301		2,171		2,116		87		534
2021																2,524		2,437		2,322		60		542
2022																		2,800		2,777		168		614
2023																				2,995		901		594
Total																				$	21,925

Overseas General Insurance — Non-Casualty — Short-tail (continued)
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	721	$	1,359		$	1,560	$	1,619	$	1,649	$	1,662	$	1,677	$	1,684	$	1,678	$	1,680
2015			812			1,469		1,691		1,769		1,790		1,819		1,836		1,839		1,839
2016						966		1,592		1,779		1,847		1,872		1,881		1,887		1,890
2017								1,010		1,772		1,940		2,013		2,055		2,114		2,091
2018										960		1,664		1,858		1,924		1,940		1,950
2019												1,019		1,674		1,861		1,926		1,959
2020														1,036		1,646		1,792		1,908
2021																982		1,750		2,025
2022																		1,168		2,088
2023																				1,119
Total																				$	18,549

(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	139
Accident years 2014 - 2023 from tables above	3,376
All Accident years	$	3,515

This product line includes proportional and excess coverages in general, automobile liability, professional liability, medical malpractice, and workers' compensation, with exposures located around the world. In general, reinsurance exhibits less stable development patterns than primary business. In particular, general casualty reinsurance and excess coverages are long-tailed and can be very volatile.

Global Reinsurance — Casualty — Long-tail (continued)
Net Incurred Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31						As of December 31  2023
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	330	$	331		$	336	$	339	$	340	$	344	$	327	$	327	$	326	$	326	$	6
2015			281			286		296		297		305		301		305		308		307		9
2016						219		223		231		230		239		239		244		250		11
2017								209		211		216		213		214		214		221		6
2018										239		242		249		245		248		255		9
2019												233		242		237		236		233		20
2020														242		246		237		237		42
2021																278		282		286		105
2022																		294		296		155
2023																				274		211
Total																				$	2,685

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	91	$	183		$	216	$	247	$	263	$	274	$	284	$	293	$	298	$	304
2015			89			158		190		215		230		247		264		273		281
2016						57		112		141		157		173		190		206		217
2017								46		99		120		138		153		173		185
2018										40		94		123		146		168		194
2019												39		89		115		138		161
2020														41		98		123		147
2021																35		86		119
2022																		39		86
2023																				30
Total																				$	1,724

Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	279
Accident years 2014 - 2023 from tables above	961
All Accident years	$	1,240

This product line includes property, property catastrophe, marine, credit/surety, mortgage, A&H and energy. This product line is impacted by natural catastrophes, particularly in the 2017, 2018, 2020, 2021, and 2022 accident years. Of the non-catastrophe book, the mixture of business varies by year with approximately 87 percent of loss on proportional treaties in treaty year 2014 and after. This percentage has increased over time with the proportion being approximately 77 percent for treaty years 2014-2017 growing to an average of 93 percent for treaty years 2018 to 2023, with the remainder being written on an excess of loss basis.

Net Incurred Loss and Allocated Loss Adjustment Expenses																						As of December 31  2023
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited																	Net IBNR Reserves
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	158	$	174		$	173	$	176	$	174	$	173	$	172	$	170	$	169	$	169	$	1
2015			144			152		158		158		151		156		154		154		154		1
2016						177		182		185		187		184		181		181		181		1
2017								395		421		451		449		453		455		454		7
2018										278		286		288		284		289		282		2
2019												130		129		125		120		116		3
2020														209		253		277		279		22
2021																340		351		354		23
2022																		346		311		69
2023																				181		109
Total																				$	2,481

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
																Years Ended December 31
(in millions of U.S. dollars)					Unaudited
Accident Year	2014		2015			2016		2017		2018		2019		2020		2021		2022		2023
2014	$	63	$	124		$	146	$	156	$	161	$	163	$	165	$	165	$	166	$	166
2015			56			102		130		140		144		148		150		150		151
2016						56		129		156		166		172		175		176		177
2017								191		321		400		413		426		433		439
2018										94		248		264		267		272		274
2019												35		80		94		102		104
2020														62		177		215		232
2021																158		277		307
2022																		74		195
2023																				36
Total																				$	2,081

Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	11
Accident years 2014 - 2023 from tables above	400
All Accident years	$	411

Supplementary PPD [Table Text Block]

North America Commercial P&C Insurance — Workers' Compensation — Long-tail (continued)
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	(113)
Accident years 2014 - 2023 from tables above	(191)
All Accident years	$	(304)

Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	47
Accident years 2014 - 2023 from tables above	175
All Accident years	$	222

North America Commercial P&C Insurance — Other-Casualty — Long-tail (continued)
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	(6)
Accident years 2014 - 2023 from tables above	99
All Accident years	$	93

Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	(4)
Accident years 2014 - 2023 from tables above	(377)
All Accident years	$	(381)

Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	3
Accident years 2014 - 2023 from tables above	(131)
All Accident years	$	(128)

Overseas General Insurance — Casualty — Long-tail (continued)
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	(22)
Accident years 2014 - 2023 from tables above	(26)
All Accident years	$	(48)

Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	(4)
Accident years 2014 - 2023 from tables above	(264)
All Accident years	$	(268)

Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	(16)
Accident years 2014 - 2023 from tables above	22
All Accident years	$	6

Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)	December 31, 2023
Accident years prior to 2014	$	—
Accident years 2014 - 2023 from tables above	(42)
All Accident years	$	(42)

Schedule of Historical Claims [Table Text Block]

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	10	%	16	%	10	%	7	%	5	%	3	%	3	%	2	%	2	%	2	%

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	4	%	13	%	15	%	16	%	12	%	8	%	6	%	4	%	4	%	2	%

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	10	%	18	%	18	%	17	%	15	%	7	%	6	%	2	%	1	%	1	%

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	44	%	37	%	8	%	3	%	1	%	1	%	1	%	—	%	—	%	—	%

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	55	%	25	%	7	%	5	%	3	%	2	%	1	%	—	%	—	%	—	%

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	7	%	13	%	13	%	11	%	9	%	9	%	6	%	3	%	3	%	4	%

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	45	%	33	%	10	%	4	%	1	%	1	%	—	%	—	%	—	%	—	%

Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	19	%	22	%	11	%	9	%	7	%	7	%	5	%	3	%	2	%	2	%

Global Reinsurance — Non-Casualty — Short-tail (continued)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2023 (Unaudited)
Age in Years	1		2		3		4		5		6		7		8		9		10
Percentage	33	%	40	%	14	%	5	%	3	%	2	%	1	%	—	%	—	%	—	%

Supplementary PPD Reconciliation [Table Text Block]

The following table presents a reconciliation of the loss development triangles above to prior period development:

	Components of PPD
Year Ended December 31, 2023 (in millions of U.S. dollars) (favorable)/unfavorable	2014 - 2022 accident years (implied PPD per loss triangles)		Accident years prior to 2014		Other (1)			PPD on loss reserves		RIPs, Expense adjustments, and earned premiums			Total
North America Commercial P&C Insurance
Long-tail	$	83	$	(72)	$	(187)		$	(176)	$	90		$	(86)
Short-tail	(377)		(4)		(35)			(416)		8			(408)
	(294)		(76)		(222)		(2)	(592)		98		(3)	(494)
North America Personal P&C Insurance (Short-tail)	(131)		3		(4)			(132)		(2)			(134)
Overseas General Insurance
Long-tail	(26)		(22)		(2)			(50)		—			(50)
Short-tail	(264)		(4)		(58)			(326)		—			(326)
	(290)		(26)		(60)		(4)	(376)		—			(376)
Global Reinsurance
Long-tail	22		(16)		1			7		—			7
Short-tail	(42)		—		—			(42)		7			(35)
	(20)		(16)		1			(35)		7			(28)
Subtotal	$	(735)	$	(115)	$	(285)		$	(1,135)	$	103		$	(1,032)
North America Agricultural Insurance (Short-tail)								$	(24)	$	6		$	(18)
Corporate (Long-tail)								277		—			277
Consolidated PPD								$	(882)	$	109		$	(773)

(1)        Other includes the impact of foreign exchange.

(2)     Includes favorable development of $88 million related to our Alternative Risk Solutions business (U.S. and Bermuda) and an adjustment to exclude $92 million in unfavorable development in the workers' compensation line, associated with an increase in exposure for which additional premiums were collected; the remaining difference relates to a number of other items, none of which are individually material.

(3)     Includes premium returns associated with our Alternative Risk Solutions business, which is excluded from the triangles.

(4)     Includes favorable development of $56 million related to International A&H business; the remaining difference relates to a number of other items, none of which are individually material.

Prior Period Development, by Segment [Table Text Block]

Years Ended December 31 (in millions of U.S. dollars, except for percentages)	Long-tail		Short-tail		Total		% of beginning net unpaid reserves (1)
2023
North America Commercial P&C Insurance	$	(86)	$	(408)	$	(494)	0.8	%
North America Personal P&C Insurance	—		(134)		(134)		0.2	%
North America Agricultural Insurance	—		(18)		(18)		—	%
Overseas General Insurance	(50)		(326)		(376)		0.6	%
Global Reinsurance	7		(35)		(28)		—	%
Corporate	277		—		277		0.5	%
Total	$	148	$	(921)	$	(773)	1.3	%
2022
North America Commercial P&C Insurance	$	(229)	$	(333)	$	(562)	1.0	%
North America Personal P&C Insurance	—		(186)		(186)		0.3	%
North America Agricultural Insurance	—		(61)		(61)		0.1	%
Overseas General Insurance	(65)		(383)		(448)		0.8	%
Global Reinsurance	(7)		29		22		—	%
Corporate	359		—		359		0.6	%
Total	$	58	$	(934)	$	(876)	1.6	%
2021
North America Commercial P&C Insurance	$	(482)	$	(280)	$	(762)	1.4	%
North America Personal P&C Insurance	—		(305)		(305)		0.6	%
North America Agricultural Insurance	—		10		10		—	%
Overseas General Insurance	(106)		(335)		(441)		0.8	%
Global Reinsurance	(25)		28		3		—	%
Corporate	569		—		569		1.1	%
Total	$	(44)	$	(882)	$	(926)	1.8	%

(1)     Calculated based on the beginning of period consolidated net unpaid losses and loss expenses.

Schedule Of Asbestos Environmental Loss Roll Forward and by segment

The following table presents a roll-forward of consolidated A&E loss reserves including allocated loss expense reserves for A&E exposures, and the valuation allowance for uncollectible paid and unpaid reinsurance recoverables:

	Asbestos				Environmental				Total
(in millions of U.S. dollars)	Gross		Net		Gross		Net		Gross		Net
Balance at December 31, 2020	$	1,351	$	873	$	517	$	379	$	1,868	$	1,252
Incurred activity	96		64		52		40		148		104		(1)
Paid activity	(221)		(137)		(167)		(117)		(388)		(254)
Balance at December 31, 2021	1,226		800		402		302		1,628		1,102
Incurred activity	87		55		125		77		212		132		(1)
Paid activity	(215)		(152)		(115)		(69)		(330)		(221)
Balance at December 31, 2022	1,098		703		412		310		1,510		1,013
Incurred activity	180		120		88		63		268		183		(1)
Paid activity	(258)		(169)		(105)		(82)		(363)		(251)
Balance at December 31, 2023	$	1,020	$	654	$	395	$	291	$	1,415	$	945

(1)    Excludes unallocated loss expenses and the net activity reflects third-party reinsurance other than the aggregate excess of loss reinsurance provided by National Indemnity Company (NICO) to Westchester Specialty (see Westchester Specialty section below).

The A&E net loss reserves including allocated loss expense reserves and valuation allowance for uncollectible reinsurance at December 31, 2023 and 2022, shown in the table above is comprised of:

	December 31
(in millions of U.S. dollars)	2023		2022
Brandywine operations	$	570	$	602
Westchester Specialty	89		98
Chubb Corp	241		266
Other, mainly Overseas General Insurance	45		47
Total	$	945	$	1,013