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Unpaid losses and loss expenses
 12 Months Ended
Dec. 31, 2020
Liability for Claims and Claims Adjustment Expense [Abstract]  
Unpaid Losses and Loss Expenses Unpaid losses and loss expenses
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, 2020 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)202020192018
Gross unpaid losses and loss expenses, beginning of year$62,690 $62,960 $63,179 
Reinsurance recoverable on unpaid losses (1)
(14,181)(14,689)(14,014)
Net unpaid losses and loss expenses, beginning of year48,509 48,271 49,165 
Net losses and loss expenses incurred in respect of losses occurring in:
Current year22,124 19,575 19,048 
Prior years (2)
(414)(845)(981)
Total21,710 18,730 18,067 
Net losses and loss expenses paid in respect of losses occurring in:
Current year7,782 7,894 7,544 
Prior years9,652 10,579 10,796 
Total17,434 18,473 18,340 
Foreign currency revaluation and other379 (19)(621)
Net unpaid losses and loss expenses, end of year53,164 48,509 48,271 
Reinsurance recoverable on unpaid losses (1)
14,647 14,181 14,689 
Gross unpaid losses and loss expenses, end of year$67,811 $62,690 $62,960 
(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 and earned premiums totaling $19 million, $53 million, and $85 million for 2020, 2019, and 2018, respectively.

The increase in gross and net unpaid losses and loss expense in 2020 was driven by catastrophe losses incurred, principally from the COVID-19 pandemic. The increase in net unpaid losses and loss expense in 2019 reflected an increase in underlying reserves, offset by favorable prior period development and payments related to catastrophic events.
The loss development tables under section c) below, present Chubb’s historical incurred and paid claims development by broad product line through December 31, 2020, net of reinsurance, as well as the cumulative number of reported claims, IBNR balances, and other supplementary information.

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, 2020
Presented in the loss development tables:
  North America Commercial P&C Insurance — Workers' Compensation$9,600 
  North America Commercial P&C Insurance — Liability17,441 
  North America Commercial P&C Insurance — Other Casualty2,124 
  North America Commercial P&C Insurance — Non-Casualty2,491 
  North America Personal P&C Insurance3,025 
  Overseas General Insurance — Casualty6,832 
  Overseas General Insurance — Non-Casualty2,725 
  Global Reinsurance — Casualty1,200 
  Global Reinsurance — Non-Casualty312 
Excluded from the loss development tables:
  Other4,742 
Net unpaid loss and allocated loss adjustment expense50,492 
Ceded unpaid loss and allocated loss adjustment expense:
  North America Commercial P&C Insurance — Workers' Compensation$1,461 
  North America Commercial P&C Insurance — Liability5,743 
  North America Commercial P&C Insurance — Other Casualty564 
  North America Commercial P&C Insurance — Non-Casualty1,380 
  North America Personal P&C Insurance141 
  Overseas General Insurance — Casualty2,426 
  Overseas General Insurance — Non-Casualty1,686 
  Global Reinsurance — Casualty29 
  Global Reinsurance — Non-Casualty104 
  Other1,153 
Ceded unpaid loss and allocated loss adjustment expense14,687 
Unpaid loss and loss expense on other than short-duration contracts (1)
1,109 
Unpaid unallocated loss adjustment expenses1,523 
Unpaid losses and loss expenses$67,811 
(1)     Primarily includes the claims reserve of our International A&H business and Life Insurance segment reserves.
Business excluded from the loss development tables
“Other” shown in the reconciliation table comprises businesses excluded from the loss development tables:
•North America Agricultural Insurance segment business, which is short-tailed with the majority of the liabilities expected to be resolved in the ensuing twelve months;
•Corporate, which includes run-off liabilities such as asbestos and environmental and other mass tort exposures and which impact accident years older than those shown in the loss development tables below;
•Life Insurance segment business, which is generally written using long-duration contracts; and
•Certain subsets of our business due to data limitations or unsuitability to the loss development table presentation, including:
◦We underwrite loss portfolio transfers at various times; by convention, all premium and losses associated with these transactions are recorded to the policy period of the transaction, even though the accident dates of the claims covered may be a decade or more in the past. We also underwrite certain high attachment, high limit, multiple-line and excess of aggregate coverages for large commercial clients. Changes in incurred loss and cash flow patterns are volatile and sufficiently different from those of typical insureds. This category includes the loss portfolio transfer of Fireman’s Fund personal lines run-off liabilities and Alternative Risk Solutions business within the North America Commercial P&C Insurance segment;
◦2015 and prior paid history on a subset of previously acquired international businesses, within the Overseas General Insurance segment, due to limitations on the data prior to the acquisition;
◦Reinsurance recoverable bad debt; and
◦Purchase accounting adjustments related to unpaid losses and loss expenses for Chubb Corp.

a) Description of Reserving Methodologies
Our recorded reserves represent management's best estimate of the provision for unpaid claims as of the balance sheet date. The process of establishing loss and loss expense reserves can be complex and is subject to considerable uncertainty as it requires the use of estimates and judgments based on circumstances underlying the insured loss at the date of accrual. The reserves for our various product lines each require different qualitative and quantitative assumptions and judgments to be made. Management's best estimate is developed after collaboration with actuarial, underwriting, claims, legal, and finance departments and culminates with the input of reserve committees. Each business unit reserve committee includes the participation of the relevant parties from actuarial, finance, claims, and unit senior management and has the responsibility for finalizing, recommending and approving the estimate to be used as management's best estimate. Reserves are further reviewed by Chubb's Chief Actuary and senior management. The objective of such a process is to determine a single estimate that we believe represents a better estimate than any other and which is viewed by management to be the best estimate of ultimate loss settlements.

This estimate is based on a combination of exposure and experience-based actuarial methods (described below) and other considerations such as claims reviews, reinsurance recovery assumptions and/or input from other knowledgeable parties such as underwriting. Exposure-based methods are most commonly used on relatively immature origin years (i.e., the year in which the losses were incurred — “accident year” or “report year”), while experience-based methods provide a view based on the projection of loss experience that has emerged as of the valuation date. Greater reliance is placed upon experience-based methods as the pool of emerging loss experience grows and where it is deemed sufficiently credible and reliable as the basis for the estimate. In comparing the held reserve for any given origin year to the actuarial projections, judgment is required as to the credibility, uncertainty and inherent limitations of applying actuarial techniques to historical data to project future loss experience. Examples of factors that impact such judgments include, but are not limited to, the following:

•nature and complexity of underlying coverage provided and net limits of exposure provided;
•segmentation of data to provide sufficient homogeneity and credibility for loss projection methods;
•extent of credible internal historical loss data and reliance upon industry information as required;
•historical variability of actual loss emergence compared with expected loss emergence;
•reported and projected loss trends;
•extent of emerged loss experience relative to the remaining expected period of loss emergence;
•rate monitor information for new and renewal business;
•changes in claims handling practice;
•inflation;
•the legal environment;
•facts and circumstances of large claims;
•terms and conditions of the contracts sold to our insured parties;
•impact of applicable reinsurance recoveries; and
•nature and extent of underlying assumptions.
We have actuarial staff within each of our business units who analyze loss reserves (including loss expenses) and regularly project estimates of ultimate losses and the corresponding indications of the required IBNR reserve. Our reserving approach is a comprehensive ground-up process using data at a detailed level that reflects the specific types and coverages of the diverse products written by our various operations. The data presented in this disclosure was prepared on a more aggregated basis and with a focus on changes in incurred loss estimates over time as well as associated cash flows. We note that data prepared on this basis may not demonstrate the full spectrum of characteristics that are evident in the more detailed level studied internally.

We perform an actuarial reserve review for each product line at least once a year. For most product lines, one or more standard actuarial reserving methods may be used to determine estimates of ultimate losses and loss expenses, and from these estimates, a single actuarial central estimate is selected. The actuarial central estimate is an input to the reserve committee process described above. For the few product lines that do not lend themselves to standard actuarial reserving methods, appropriate techniques are applied to produce the actuarial central estimates. For example, run-off asbestos and environmental liability estimates are better suited to the application of account-specific exposure-based analyses to best evaluate their associated aggregate reserve levels.

b) Standard actuarial reserving methods
The judgments involved in projecting the ultimate losses include the use and interpretation of various standard actuarial reserving methods that place reliance on the extrapolation of actual historical data, loss development patterns, industry data, and other benchmarks as appropriate.

Standard actuarial reserving methods include, but are not limited to, expected loss ratio, paid and reported loss development, and Bornhuetter-Ferguson methods. A general description of these methods is provided below. In addition to these standard methods, depending upon the product line characteristics and available data, we may use other recognized actuarial methods and approaches. Implicit in the standard actuarial methods that we generally utilize is the need for two fundamental assumptions: first, the pattern by which losses are expected to emerge over time for each origin year, and second the expected loss ratio for each origin year.

The expected loss ratio for any particular origin year is selected after consideration of a number of factors, including historical loss ratios adjusted for rate changes, premium and loss trends, industry benchmarks, the results of policy level loss modeling at the time of underwriting, and/or other more subjective considerations for the product line (e.g., terms and conditions) and external environment as noted above. The expected loss ratio for a given origin year is initially established at the start of the origin year as part of the planning process. This analysis is performed in conjunction with underwriters and management. The expected loss ratio method arrives at an ultimate loss estimate by multiplying the expected ultimate loss ratio by the corresponding premium base. This method is most commonly used as the basis for the actuarial central estimate for immature origin periods on product lines where the actual paid or reported loss experience is not yet deemed sufficiently credible to serve as the principal basis for the selection of ultimate losses. The expected loss ratio for a given origin year may be modified over time if the underlying assumptions differ from the original assumptions (e.g., the assessment of prior year loss ratios, loss trend, rate changes, actual claims, or other information).

Our selected paid and reported development patterns provide a benchmark against which the actual emerging loss experience can be monitored. Where possible, development patterns are selected based on historical loss emergence by origin year. For product lines where the historical data is viewed to have low statistical credibility, the selected development patterns also reflect relevant industry benchmarks and/or experience from similar product lines written elsewhere within Chubb. This most commonly occurs for relatively new product lines that have limited historical data or for high severity/low frequency portfolios where our historical experience exhibits considerable volatility and/or lacks credibility. The paid and reported loss development methods convert the selected loss emergence pattern to a set of multiplicative factors which are then applied to actual paid or reported losses to arrive at an estimate of ultimate losses for each period. Due to their multiplicative nature, the paid and reported loss development methods will leverage differences between actual and expected loss emergence. These methods tend to be utilized for more mature origin periods and for those portfolios where the loss emergence has been relatively consistent over time.

The Bornhuetter-Ferguson method is a combination of the expected loss ratio method and the loss development method, where the loss development method is given more weight as the origin year matures. This approach allows a logical transition between the expected loss ratio method which is generally utilized at earlier maturities and the loss development methods which are typically utilized at later maturities. We usually apply this method using reported loss data although paid data may also be used.
Short-tail business
Short-tail business generally describes product lines for which losses are typically known and paid shortly after the loss occurs. This would include, for example, most property, personal accident, and automobile physical damage policies that we write. Due to the short reporting and development pattern for these product lines, the uncertainty associated with our estimate of ultimate losses for any particular accident period diminishes relatively quickly as actual loss experience emerges. We typically assign credibility to methods that incorporate actual loss emergence, such as the paid and reported loss development and Bornhuetter-Ferguson methods, sooner than would be the case for long-tail lines at a similar stage of development for a given origin year. The reserving process for short-tail losses arising from catastrophic events typically involves an assessment by the claims department, in conjunction with underwriters and actuaries, of our exposure and estimated losses immediately following an event and then subsequent revisions of the estimated losses as our insureds provide updated actual loss information.

Long-tail business
Long-tail business describes lines of business for which specific losses may not be known/reported for some period and for which claims can take significant time to settle/close. This includes most casualty lines such as general liability, D&O, and workers' compensation. There are various factors contributing to the uncertainty and volatility of long-tail business. Among these are:
•The nature and complexity of underlying coverage provided and net limits of exposure provided;
•Our historical loss data and experience is sometimes too immature and lacking in credibility to rely upon for reserving purposes. Where this is the case, in our reserve analysis we may utilize industry loss ratios or industry benchmark development patterns that we believe reflect the nature and coverage of the underwritten business and its future development, where available. For such product lines, actual loss experience may differ from industry loss statistics as well as loss experience for previous underwriting years;
•The difficulty in estimating loss trends, claims inflation (e.g., medical and judicial) and underlying economic conditions;
•The need for professional judgment to estimate loss development patterns beyond that represented by historical data using supplemental internal or industry data, extrapolation, or a blend of both;
•The need to address shifts in business mix or volume over time when applying historical paid and reported loss development patterns from older origin years to more recent origin years. For example, changes over time in the processes and procedures for establishing case reserves can distort reported loss development patterns or changes in ceded reinsurance structures by origin year can alter the development of paid and reported losses;
•Loss reserve analyses typically require loss or other data be grouped by common characteristics in some manner. If data from two combined lines of business exhibit different characteristics, such as loss payment patterns, the credibility of the reserve estimate could be affected. Additionally, since casualty lines of business can have significant intricacies in the terms and conditions afforded to the insured, there is an inherent risk as to the homogeneity of the underlying data used in performing reserve analyses; and
•The applicability of the price change data used to estimate ultimate loss ratios for most recent origin years.

As described above, various factors are considered when determining appropriate data, assumptions, and methods used to establish the loss reserve estimates for long-tail product lines. These factors may also vary by origin year for given product lines. The derivation of loss development patterns from data and the selection of a tail factor to project ultimate losses from actual loss emergence require considerable judgment, particularly with respect to the extent to which historical loss experience is relied upon to support changes in key reserving assumptions.

c) Loss Development Tables
The tables were designed to present business with similar risk characteristics which exhibit like development patterns and generally similar trends, in order to provide insight into the nature, amount, timing and uncertainty of cash flows related to our claims liabilities.

Each table follows a similar format and reflects the following:
•The incurred loss triangle includes both reported case reserves and IBNR liabilities.
•Both the incurred and paid loss triangles include allocated loss adjustment expense (i.e., defense and investigative costs particular to individual claims) but exclude unallocated loss adjustment expense (i.e., the costs associated with internal claims staff and third-party administrators).
•The amounts in both triangles for the years ended December 31, 2011 to December 31, 2019 and average historical claim duration as of December 31, 2020, are presented as supplementary information.
•All data presented in the triangles is net of reinsurance recoverables.
•The IBNR reserves shown to the right of each incurred loss development exhibit reflect the net IBNR recorded as of December 31, 2020.
•The tables are presented retrospectively with respect to acquisitions where these are material and doing so is practicable. Most notably, the Chubb Corp acquisition is presented retrospectively. The unaudited consolidated data is presented solely for informational purposes and is not necessarily indicative of the consolidated data that might have been observed had the transactions been completed prior to the date indicated.

Historical dollar amounts are presented in this footnote on a constant-dollar basis, which is achieved by assuming constant foreign exchange rates for all periods in the loss triangles, translating prior period amounts using the same local currency exchange rates as the current year end. The impact of this conversion is to show the change between periods exclusive of the effect of fluctuations in exchange rates, which would otherwise distort the change in incurred loss and cash flow patterns shown. The change in incurred loss shown will differ from other GAAP disclosures of incurred prior period reserve development amounts, which include the effect of fluctuations in exchanges rates.

We provided guidance above on key assumptions that should be considered when reviewing this disclosure and information relating to how loss reserve estimates are developed. We believe the information provided in the “Loss Development Tables” section of the disclosure is of limited use for independent analysis or application of standard actuarial estimations.

Cumulative Number of Reported Claims
Reported claim counts, on a cumulative basis, are provided to the far right of each incurred loss development table. In our North America segments, we generally consider a reported claim to be one claim per coverage per claimant. For our North America segments, we refined our claim count methodology in 2020 for our U.S. operations. For workers' compensation, we moved from including losses below the deductible in our reported claims to excluding them. This reduction in reported claims aligns claim counts to the portion of the claims to which Chubb has incurred losses, which we view as a more meaningful presentation. For non-casualty, personal and liability, we aligned our claim count methodology to reflect a reported claim per claimant, per coverage basis, and including all reported claims with either an indemnity or expense transaction. These changes resulted in fewer reported claims in non-casualty and additional reported claims in personal and liability. In our Overseas General Insurance segment, we generally consider a reported claim to be on a per occurrence basis. Global Reinsurance segment’s portfolio comprises a mix of proportional and non-proportional treaties. The proportional treaties are reported on a bulk basis and do not lend themselves to meaningful claim count data. As such, we do not provide claim count information for our Global Reinsurance segment.

We exclude claims closed without payment. Claims are counted on a direct basis without consideration of ceded reinsurance. Use of the presented claim counts in analysis of company experience has significant limitations, including:
•Claims for certain events and/or product lines, such as portions of our A&H business, are not reported on an individual basis, but rather in bulk and thus not available for inclusion in this disclosure.
•Each segment typically has a mixture of primary and excess experience which has shifted over time.
•Captive business, especially in Workers' Compensation and Liability, largely represents fronted business where our net exposure to loss is minimal; however, since the claim count is based on direct claims, there is a mismatch between direct claims and net loss dollars, the extent of which varies by accident year.

Reported claim counts include open claims which have case reserves but exclude claims that have been incurred but not reported. As such the reported claims are not consistent with the incurred losses in the triangle, which include incurred but not reported losses. One can calculate reported losses by subtracting incurred but not reported losses from incurred losses in the triangle. Reported claim counts are also inconsistent with losses in the paid loss triangle, since reported counts would include claims with case reserves but no payments to date.

North America Commercial P&C Insurance — Workers' Compensation — Long-tail
This product line has a substantial geographic spread and a broad mix across industries. 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-58.
North America Commercial P&C Insurance — Workers' Compensation — Long-tail (continued)
Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31 As of December 31 2020
(in millions of U.S. dollars)UnauditedNet IBNR Reserves
Reported Claims (in thousands)
Accident Year2011201220132014201520162017201820192020
2011$1,037 $1,030 $1,046 $1,049 $1,053 $1,022 $1,012 $1,009 $988 $973 $208 45 
20121,050 1,011 1,030 1,040 1,011 989 986 977 953 234 44 
20131,109 1,108 1,122 1,127 1,086 1,073 1,037 1,014 280 43 
20141,207 1,201 1,217 1,215 1,163 1,100 1,073 347 45 
20151,282 1,259 1,276 1,279 1,217 1,154 419 50 
20161,367 1,361 1,383 1,378 1,269 530 51 
20171,413 1,380 1,399 1,393 723 50 
20181,359 1,361 1,379 709 51 
20191,391 1,384 767 47 
20201,367 1,086 24 
Total$11,959 
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$119 $294 $411 $484 $533 $567 $595 $616 $640 $654 
2012111 271 365 436 486 532 574 592 612 
2013107 286 422 506 553 587 616 633 
2014113 295 410 484 532 566 599 
2015116 301 418 501 564 606 
2016122 326 452 529 584 
2017120 313 437 516 
2018130 329 451 
2019143 341 
2020111 
Total$5,107 
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$2,748 
Accident years 2011 - 2020 from tables above6,852 
All Accident years$9,600 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$(94)
Accident years 2011 - 2020 from tables above(256)
All Accident years$(350)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage10 %16 %10 %7 %5 %4 %3 %2 %2 %1 %
North America Commercial P&C Insurance — Liability — Long-tail
This line consists of primary and excess liability exposures, including 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 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 31As of December 31 2020
(in millions of U.S. dollars)UnauditedNet IBNR Reserves
Reported Claims (in thousands)
Accident Year2011201220132014201520162017201820192020
2011$3,500 $3,586 $3,630 $3,665 $3,593 $3,498 $3,384 $3,316 $3,193 $3,143 $226 25 
20123,552 3,628 3,613 3,565 3,524 3,426 3,331 3,235 3,235 353 25 
20133,547 3,542 3,543 3,533 3,430 3,216 3,122 2,964 317 25 
20143,535 3,586 3,674 3,717 3,656 3,470 3,346 572 25 
20153,560 3,709 3,819 3,976 3,943 3,736 855 27 
20163,534 3,595 3,692 3,805 3,799 962 27 
20173,322 3,499 3,581 3,631 1,475 27 
20183,375 3,494 3,696 1,737 28 
20193,452 3,628 2,381 28 
20204,098 3,695 24 
Total$35,276 
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$160 $652 $1,209 $1,805 $2,214 $2,477 $2,659 $2,741 $2,827 $2,863 
2012166 656 1,172 1,680 2,092 2,326 2,502 2,619 2,688 
2013130 548 1,192 1,597 2,007 2,232 2,374 2,465 
2014164 679 1,250 1,804 2,202 2,442 2,584 
2015138 605 1,206 1,856 2,291 2,533 
2016171 663 1,336 1,975 2,334 
2017161 617 1,162 1,701 
2018190 754 1,303 
2019176 671 
2020152 
Total$19,294 
North America Commercial P&C Insurance — Liability — Long-tail (continued)
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$1,459 
Accident years 2011 - 2020 from tables above15,982 
All Accident years$17,441 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$(176)
Accident years 2011 - 2020 from tables above(117)
All Accident years$(293)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage5 %14 %17 %16 %12 %7 %5 %3 %2 %1 %

North America Commercial P&C Insurance — Other Casualty — Long-tail
This product line consists of the remaining commercial casualty coverages such as automobile liability and aviation. There is also a small portion of commercial multi-peril (CMP) business in accident years 2014 and prior. The paid and reported data are impacted by some catastrophe loss activity primarily on the CMP exposures just noted.
Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31As of December 31 2020
(in millions of U.S. dollars)UnauditedNet IBNR Reserves
Reported Claims (in thousands)
Accident Year2011201220132014201520162017201820192020
2011$581 $590 $581 $549 $533 $525 $517 $511 $513 $503 $13 16 
2012634 606 577 561 520 519 509 507 505 2 16 
2013527 531 523 516 469 462 462 458 21 18 
2014595 583 581 597 555 539 539 25 17 
2015487 470 502 515 458 455 35 15 
2016504 502 527 524 481 61 16 
2017532 566 577 616 118 17 
2018536 564 575 198 17 
2019606 637 284 16 
2020646 517 9 
Total$5,415 
North America Commercial P&C Insurance — Other-Casualty — Long-tail (continued)
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$86 $235 $341 $400 $437 $461 $466 $480 $486 $486 
201269 223 320 387 435 470 487 493 502 
201369 197 271 348 385 411 419 426 
201480 220 318 391 455 474 501 
201547 137 215 305 371 395 
201652 146 246 323 374 
201766 175 313 381 
201874 169 270 
201970 190 
202053 
Total$3,578 
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$287 
Accident years 2011 - 2020 from tables above1,837 
All Accident years$2,124 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$23 
Accident years 2011 - 2020 from tables above19 
All Accident years$42 
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage12 %23 %19 %14 %10 %5 %3 %2 %1 %— %
North America Commercial P&C Insurance — Non-Casualty — Short-tail
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 also impacted by natural catastrophes mainly in the 2012, 2017, and 2018 accident years.
Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31As of December 31 2020
(in millions of U.S. dollars)UnauditedNet IBNR Reserves
Reported Claims (in thousands)
Accident Year2011201220132014201520162017201820192020
2011$1,960 $1,934 $1,877 $1,856 $1,835 $1,840 $1,835 $1,835 $1,835 $1,833 $4 416 
20122,033 1,916 1,883 1,864 1,859 1,847 1,844 1,850 1,844 (8)426 
20131,434 1,424 1,337 1,360 1,340 1,340 1,338 1,344 7 455 
20141,643 1,661 1,579 1,559 1,549 1,550 1,558 10 483 
20151,736 1,745 1,650 1,638 1,605 1,589 (1)545 
20161,911 1,890 1,799 1,782 1,818 32 650 
20172,704 2,608 2,505 2,522 51 763 
20182,053 2,240 2,175 71 901 
20192,052 2,037 166 1,036 
20203,150 1,061 927 
Total$19,870 
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$939 $1,574 $1,718 $1,777 $1,787 $1,811 $1,816 $1,821 $1,825 $1,830 
2012715 1,577 1,698 1,767 1,795 1,822 1,816 1,842 1,844 
2013651 1,138 1,238 1,285 1,311 1,324 1,333 1,335 
2014820 1,374 1,484 1,506 1,532 1,546 1,554 
2015727 1,343 1,488 1,556 1,572 1,574 
2016846 1,504 1,656 1,733 1,761 
2017979 2,087 2,303 2,394 
20181,027 1,825 2,018 
20191,030 1,677 
20201,396 
Total$17,383 
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$4 
Accident years 2011 - 2020 from tables above2,487 
All Accident years$2,491 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$2 
Accident years 2011 - 2020 from tables above(37)
All Accident years$(35)
North America Commercial P&C Insurance — Non-Casualty — Short-tail (continued)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage46 %38 %8 %3 %1 %1 %— %1 %— %— %

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. A portfolio acquired from Fireman’s Fund is presented on a prospective basis beginning in May of accident year 2015. Reserves associated with prior accident periods were acquired through a loss portfolio transfer, which does not allow for a retrospective presentation. During this ten-year period, this segment was also impacted by natural catastrophes, mainly in 2012, 2017 and 2018 accident years.
Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31As of December 31 2020
(in millions of U.S. dollars)UnauditedNet IBNR Reserves
Reported Claims (in thousands)
Accident Year2011201220132014201520162017201820192020
2011$2,208 $2,210 $2,185 $2,173 $2,164 $2,161 $2,160 $2,158 $2,159 $2,157 $7 179 
20122,185 2,183 2,183 2,191 2,186 2,186 2,189 2,194 2,190 18 188 
20131,860 1,888 1,897 1,900 1,924 1,937 1,945 1,948 26 132 
20142,205 2,206 2,192 2,146 2,160 2,147 2,141 14 144 
20152,494 2,550 2,561 2,544 2,563 2,570 21 148 
20162,440 2,535 2,545 2,482 2,471 45 154 
20173,035 3,069 3,002 2,998 96 163 
20183,010 3,037 3,103 244 169 
20192,957 2,993 329 155 
20202,931 1,119 100 
Total$25,502 

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$1,360 $1,835 $1,972 $2,052 $2,105 $2,129 $2,139 $2,146 $2,148 $2,149 
20121,177 1,806 1,957 2,063 2,117 2,149 2,164 2,163 2,165 
20131,043 1,504 1,688 1,787 1,843 1,885 1,895 1,917 
20141,310 1,765 1,926 2,035 2,080 2,106 2,116 
20151,499 2,084 2,271 2,392 2,478 2,508 
20161,453 2,052 2,211 2,314 2,370 
20171,698 2,520 2,668 2,799 
20181,926 2,549 2,706 
20191,668 2,437 
20201,334 
Total$22,501 
North America Personal P&C Insurance — Short-tail (continued)
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$24 
Accident years 2011 - 2020 from tables above3,001 
All Accident years$3,025 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$(1)
Accident years 2011 - 2020 from tables above85 
All Accident years$84 
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage57 %24 %7 %5 %3 %1 %1 %— %— %— %

Overseas General Insurance — Casualty — Long-tail
This product line is comprised of 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 45 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 comprised of a mix of primary and excess businesses.

Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31As of December 31 2020
(in millions of U.S. dollars)UnauditedNet IBNR Reserves
Reported Claims (in thousands)
Accident Year2011201220132014201520162017201820192020
2011$1,255 $1,262 $1,254 $1,244 $1,158 $1,090 $1,079 $1,027 $1,023 $1,025 $31 37 
20121,290 1,261 1,326 1,346 1,343 1,337 1,315 1,304 1,272 87 38 
20131,281 1,279 1,276 1,322 1,276 1,242 1,182 1,148 86 39 
20141,279 1,352 1,362 1,378 1,293 1,206 1,165 151 39 
20151,196 1,296 1,328 1,351 1,326 1,265 199 41 
20161,232 1,337 1,407 1,437 1,425 341 43 
20171,227 1,332 1,381 1,433 384 43 
20181,330 1,383 1,447 671 43 
20191,409 1,480 809 40 
20201,810 1,493 28 
Total$13,470 
Overseas General Insurance — Casualty — Long-tail (continued)
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$86 $243 $393 $528 $631 $713 $789 $842 $876 $901 
201275 252 441 597 713 857 929 973 1,040 
201385 267 428 579 725 829 899 952 
2014111 293 473 608 725 811 876 
201586 287 497 679 802 884 
2016127 324 534 687 815 
201798 323 535 702 
2018112 334 503 
2019126 341 
2020110 
Total$7,124 
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$486 
Accident years 2011 - 2020 from tables above6,346 
All Accident years$6,832 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$(59)
Accident years 2011 - 2020 from tables above9 
All Accident years$(50)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage8 %15 %15 %12 %10 %8 %6 %4 %4 %3 %

Overseas General Insurance — Non-Casualty — Short-tail
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 2011, 2017, and 2018 accident years. Latin America and Europe each make up about 30 percent of the Chubb Overseas General non-casualty book.
Overseas General Insurance — Non-Casualty — Short-tail (continued)
Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31As of December 31 2020
(in millions of U.S. dollars)UnauditedNet IBNR Reserves
Reported Claims (in thousands)
Accident Year2011201220132014201520162017201820192020
2011$1,908 $1,995 $1,938 $1,898 $1,879 $1,867 $1,859 $1,849 $1,844 $1,843 $6 543 
20121,712 1,702 1,661 1,605 1,599 1,590 1,575 1,570 1,562 13 555 
20131,787 1,780 1,714 1,665 1,660 1,633 1,620 1,610 19 573 
20141,863 1,932 1,875 1,864 1,828 1,817 1,810 7 548 
20151,963 2,083 2,062 2,030 2,011 2,003 24 571 
20162,070 2,071 2,058 2,036 2,040 22 581 
20172,222 2,264 2,245 2,225 18 589 
20182,186 2,276 2,237 48 624 
20192,208 2,228 94 640 
20202,571 804 518 
Total$20,129 
Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$765 $1,486 $1,694 $1,750 $1,780 $1,795 $1,804 $1,808 $1,807 $1,806 
2012679 1,237 1,425 1,485 1,508 1,518 1,530 1,532 1,532 
2013696 1,284 1,480 1,512 1,549 1,567 1,575 1,578 
2014758 1,438 1,651 1,715 1,746 1,759 1,774 
2015857 1,560 1,793 1,875 1,897 1,927 
20161,013 1,679 1,881 1,954 1,981 
20171,051 1,848 2,029 2,106 
20181,006 1,753 1,962 
20191,050 1,747 
20201,085 
Total$17,498 
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$94 
Accident years 2011 - 2020 from tables above2,631 
All Accident years$2,725 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$(8)
Accident years 2011 - 2020 from tables above(69)
All Accident years$(77)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage45 %35 %11 %3 %2 %1 %1 %— %— %— %
Global Reinsurance
Chubb analyzes its Global Reinsurance business on a treaty year basis rather than on an accident year basis. Treaty year data was converted to an accident year basis for the purposes of this disclosure. Mix shifts are an important consideration in these product line groupings. As proportional business and excess of loss business have different earning and loss reporting and payment patterns, this change in mix will affect the cash flow patterns across the accident years. In addition, the shift from excess to proportional business over time will make the cash flow patterns of older and more recent years difficult to compare. In general, the proportional business will pay out more quickly than the excess of loss business, as such, using older years development patterns may overstate the ultimate loss estimates in more recent years.

Global Reinsurance — Casualty — Long-tail
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.

Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31As of December 31
2020
(in millions of U.S. dollars)UnauditedNet
IBNR
Reserves
Accident Year2011201220132014201520162017201820192020
2011$408 $415 $430 $433 $428 $418 $415 $409 $402 $389 $15 
2012387 384 392 395 379 373 372 374 379 11 
2013321 327 330 331 332 324 317 311 13 
2014334 335 340 343 345 348 331 16 
2015285 290 300 301 309 306 22 
2016224 228 236 236 245 27 
2017215 217 221 218 28 
2018246 249 256 48 
2019239 248 90 
2020247 153 
Total$2,930 

Net Cumulative Paid Loss and Allocated Loss Adjustment Expenses
Years Ended December 31
(in millions of U.S. dollars)Unaudited
Accident Year2011201220132014201520162017201820192020
2011$70 $146 $195 $236 $267 $292 $312 $325 $332 $338 
201278 168 223 262 293 309 324 336 342 
201365 143 186 222 242 260 269 272 
201492 185 218 249 265 277 287 
201590 159 192 217 233 250 
201658 113 143 159 175 
201747 100 122 140 
201842 96 126 
201940 90 
202041 
Total$2,061 
Global Reinsurance — Casualty — Long-tail (continued)
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$331 
Accident years 2011 - 2020 from tables above869 
All Accident years$1,200 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$(10)
Accident years 2011 - 2020 from tables above(12)
All Accident years$(22)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage21 %23 %12 %10 %7 %5 %4 %3 %2 %2 %

Global Reinsurance — Non-Casualty — Short-tail
This product line includes property, property catastrophe, marine, credit/surety, A&H and energy. This product line is impacted by natural catastrophes, particularly in the 2011, 2017 and 2018 accident years. Of the non-catastrophe book, the mixture of business varies by year with approximately 77 percent of loss on proportional treaties in treaty year 2011 and after. This percentage has increased over time with the proportion being approximately 59 percent for treaty years 2011 to 2012 growing to an average of 82 percent for treaty years 2013 to 2020, with the remainder being written on an excess of loss basis.
Global Reinsurance — Non-Casualty — Short-tail (continued)

Net Incurred Loss and Allocated Loss Adjustment Expenses
Years Ended December 31As of December 31
2020
(in millions of U.S. dollars)UnauditedNet
IBNR
Reserves
Accident Year2011201220132014201520162017201820192020
2011$277 $279 $276 $266 $267 $268 $267 $268 $267 $269 $1 
2012233 211 202 192 191 188 186 186 184 1 
2013162 160 148 143 144 141 141 140 — 
2014167 182 183 186 184 183 182 3 
2015147 155 162 162 155 161 4 
2016184 189 192 194 190 5 
2017397 424 454 451 10 
2018288 300 303 (8)
2019143 141 29 
2020212 110 
Total$2,233 
Global Reinsurance — 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 Year2011201220132014201520162017201820192020
2011$87 $179 $210 $236 $254 $259 $262 $263 $264 $265 
201245 130 157 167 173 178 180 181 180 
201346 103 121 131 134 137 137 139 
201466 131 154 165 171 173 175 
201556 104 133 143 147 153 
201657 133 161 172 178 
2017191 322 402 415 
201894 258 277 
201935 86 
202063 
Total$1,931 
Net Liabilities for Loss and Allocated Loss Adjustment Expenses
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$10 
Accident years 2011 - 2020 from tables above302 
All Accident years$312 
Supplementary Information: (Favorable)/ Adverse Prior Period Development
(in millions of U.S. dollars)December 31, 2020
Accident years prior to 2011$— 
Accident years 2011 - 2020 from tables above(2)
All Accident years$(2)
Supplementary Information: Average Annual Percentage Payout of Net Incurred Claims by Age, as of December 31, 2020 (Unaudited)
Age in Years1 2 3 4 5 6 7 8 9 10 
Percentage33 %38 %14 %6 %4 %2 %1 %1 %— %— %
Prior Period Development — Supplementary Information

The following table presents a reconciliation of the loss development triangles above to prior period development:
Components of PPD
Year Ended December 31, 2020 (in millions of U.S. dollars)
(favorable)/unfavorable		2011 - 2019 accident years (implied PPD per loss triangles)Accident years prior to 2011
Other (1)
PPD on loss reserves RIPs, Expense adjustments, and earned premiumsTotal
North America Commercial P&C Insurance
Long-tail$(354)$(247)$(102)$(703)$31 $(672)
Short-tail(37)2 5 (30)— (30)
(391)(245)(97)(2)(733)31 (3)(702)
North America Personal P&C Insurance (Short-tail)85 (1)(3)81 (18)63 
Overseas General Insurance
Long-tail9 (59)1 (49)— (49)
Short-tail(69)(8)(24)(101)— (101)
(60)(67)(23)(4)(150)— (150)
Global Reinsurance
Long-tail(12)(10)(1)(23)(2)(25)
Short-tail(2)— (1)(3)(1)(4)
(14)(10)(2)(26)(3)(29)
Subtotal$(380)$(323)$(125)$(828)$10 $(818)
North America Agricultural Insurance (Short-tail)$(19)$9 $(10)
Corporate (Long-tail)433 — 433 
Consolidated PPD$(414)$19 $(395)
(1)        Other includes the impact of foreign exchange.
(2)     Includes favorable development of $80 million related to our Alternative Risk Solutions business (U.S. and Bermuda) and an adjustment to exclude $15 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 $22 million related to International A&H business; the remaining difference relates to a number of other items, none of which are individually material.
Prior Period Development
Prior period development (PPD) arises from changes to loss estimates recognized in the current year that relate to loss events that occurred in previous calendar years and excludes the effect of losses from the development of earned premium from previous accident years. Long-tail lines include lines such as workers' compensation, general liability, and professional liability; while short-tail lines include lines such as most property lines, energy, personal accident, and agriculture. The following table summarizes (favorable) and adverse PPD by segment:
Years Ended December 31
(in millions of U.S. dollars, except for percentages)		Long-tailShort-tailTotal
% of beginning net unpaid reserves (1)
2020
North America Commercial P&C Insurance$(672)$(30)$(702)1.4 %
North America Personal P&C Insurance— 63 63 0.1 %
North America Agricultural Insurance— (10)(10)— %
Overseas General Insurance(49)(101)(150)0.3 %
Global Reinsurance(25)(4)(29)0.1 %
Corporate433 — 433 0.9 %
Total$(313)$(82)$(395)0.8 %
2019
North America Commercial P&C Insurance$(668)$19 $(649)1.3 %
North America Personal P&C Insurance— (95)(95)0.2 %
North America Agricultural Insurance— (80)(80)0.2 %
Overseas General Insurance(68)(24)(92)0.2 %
Global Reinsurance(59)30 (29)0.1 %
Corporate153 — 153 0.3 %
Total$(642)$(150)$(792)1.6 %
2018
North America Commercial P&C Insurance$(395)$(215)$(610)1.2 %
North America Personal P&C Insurance— 41 41 0.1 %
North America Agricultural Insurance— (110)(110)0.2 %
Overseas General Insurance(67)(145)(212)0.4 %
Global Reinsurance(69)19 (50)0.1 %
Corporate 45 — 45 0.1 %
Total$(486)$(410)$(896)1.8 %
(1)     Calculated based on the beginning of period consolidated net unpaid losses and loss expenses.

Significant prior period movements by segment, principally driven by reserve reviews completed during each respective period, are discussed in more detail below. The remaining net development for long-tail lines and short-tail business for each segment and Corporate comprises numerous favorable and adverse movements across a number of lines and accident years, none of which is significant individually or in the aggregate.

North America Commercial P&C Insurance
2020
North America Commercial P&C Insurance experienced net favorable PPD of $702 million, which was the net result of several underlying favorable and adverse movements, and was driven by the following principal changes:
•Net favorable development of $672 million in long-tail business, primarily from:

•Net favorable development of $363 million in workers’ compensation lines. The majority of the favorable development related to accident years 2016 and prior, driven by lower than expected loss emergence and related updates to loss development factors. In addition, we experienced favorable development of $62 million related to our annual assessment of multi-claimant events, including industrial accidents, in the 2019 accident year. Consistent with prior
years, we reviewed these potential exposures after the close of the accident year to allow for late reporting or identification of significant losses. This favorable development in accident year 2019 was partially offset by some higher than expected activity from other claims;

•Net favorable development of $231 million in management liability portfolios, favorably impacting accident years 2015 and prior where paid and reported loss activity was lower than expected, partially offset by adverse development in the 2016 through 2019 accident years, mainly due to higher than expected claim severity in our Directors and Officers (D&O) portfolios;

•Net favorable development of $83 million in commercial excess and umbrella portfolios, mainly in accident years 2014 and prior, driven by lower paid and reported loss activity relative to prior expectations as well as an increase in weighting towards experience-based methods, partially offset by adverse development in more recent accident years, due to higher than expected loss activity;

•Net favorable development of $67 million in professional liability (errors & omissions and cyber risk), driven by accident years 2016 and prior, which experienced lower than expected loss emergence;

•Net favorable development of $43 million in voluntary environmental lines, in accident years 2016 and prior, due to lower than expected loss emergence and a related update to loss development factors;

•Net favorable development of $41 million on large multi-line prospective deals in the 2016 and prior accident years, due to lower than expected reported loss activity. These structured deals typically cover large clients for multiple product lines and with varying loss limitations; this development is net of premium returns of $26 million tied to the loss performance of the particular deals;

•Net favorable development of $40 million in foreign casualty businesses, mainly in accident year 2016, due to lower than expected reported loss activity, partially offset by adverse development on a large loss in accident year 2017;

•Net adverse development of $48 million in general liability coverages, driven by higher than expected reported loss activity in accident years 2017 through 2019, partially offset by favorable development in older accident years;

•Net adverse development of $64 million in medical liability businesses, mainly impacting accident years 2016 through 2019, primarily due to higher than expected reported loss emergence and associated changes to loss development factors and loss expectations; and

•Net adverse development of $77 million in commercial automobile liability, mainly in high deductible and excess portfolios, driven by adverse paid and reported loss emergence and related updates to loss development factors, mainly in accident years 2015 through 2019.

•Net favorable development of $30 million in short-tail business primarily from:

•Net favorable development of $37 million, in accident & health, mainly in accident years 2018 and 2019, driven by lower than expected paid loss emergence;

•Net favorable development of $31 million in surety businesses, driven by accident year 2018, where loss emergence was lower than expected; and

•Net adverse development of $21 million in our marine portfolios, mainly impacting the 2019 accident year, driven by higher than expected non-catastrophe loss development.

2019
North America Commercial P&C Insurance experienced net favorable PPD of $649 million, which was the net result of several underlying favorable and adverse movements, and was driven by the following principal changes:
•Net favorable development of $668 million in long-tail business, primarily from:

•Net favorable development of $303 million in workers’ compensation lines. This included favorable development of $61 million related to our annual assessment of multi-claimant events including industrial accidents, in the 2018 accident year. Consistent with prior years, we reviewed these potential exposures after the close of the accident year to allow for late reporting or identification of significant losses. This development in accident year 2018 was partially
offset by some higher than expected activity from other claims and from involuntary pools. The remaining overall favorable development was mainly in accident years 2015 and prior, generally driven by lower than expected loss experience and related updates to loss development factors;

•Net favorable development of $217 million in management liability portfolios, favorably impacting accident years 2015 and prior where paid and reported loss activity was lower than expected, partially offset by adverse development in the 2016 through 2018 accident years, mostly as a result of higher severity claim costs compared to prior expectations in certain lines or coverages, particularly in our Directors and Officers (D&O) portfolios;

•Net favorable development of $60 million in professional liability (errors & omissions and cyber), mainly in the 2015 and prior accident years where case activity was less than expected, partially offset by adverse development in the 2016 accident year, which was driven by several large adverse claim developments;

•Net favorable development of $41 million in commercial excess and umbrella portfolios, mainly in accident years 2013 and prior driven by lower paid and reported loss activity relative to prior expectations as well as an increase in weighting towards experience-based methods, partly offset by modestly adverse development in more recent accident years, mainly in 2017 and 2018, due to higher than expected large loss activity;

•Net favorable development of $39 million in foreign casualty business, impacting accident years 2015 and prior, driven by reported loss activity that was generally lower than expected;

•Net favorable development of $36 million on large multi-line prospective deals in the 2015 and prior accident years, due to lower than expected reported loss activity. These structured deals typically cover large clients for multiple product lines and with varying loss limitations; this development is net of premium returns of $34 million tied to the loss performance of the particular deals;

•Net favorable development of $24 million in medical and life sciences businesses, mainly impacting accident years 2015 and prior, primarily due to favorable reported experience and an increase in weighting towards experience-based methods;

•Favorable development of $23 million in political risk and trade credit portfolios, mainly impacting the 2015 accident year, primarily due to favorable reported experience and an increase in weighting towards experience-based methods;

•Net adverse development of $26 million mainly in products and general liability portfolios, including adverse movements within construction, partly offset by commercial-multi peril (CMP) liability, with older accident years generally experiencing favorable run-off, while more recent accident years developing adversely; and

•Net adverse development of $38 million in automobile liability, driven by adverse paid and reported loss experience mainly in accident years 2014 through 2018.

•Net adverse development of $19 million in short-tail business, primarily from:

•Net adverse development, excluding catastrophes, of $108 million in property and marine portfolios with adverse development of $152 million across our retail, wholesale, and program distribution channels in accident year 2018, primarily due to a higher than expected severity of non-catastrophe claims, partly offset by favorable development of $44 million in 2017 and prior accident years on non-catastrophe claims;

•Net favorable catastrophe development in property and marine portfolios of $36 million. There was $41 million of favorable development on the 2017 and 2018 natural catastrophes, mostly in 2017, partly offset by some adverse development on older catastrophe events; and

•Favorable development of $49 million in surety businesses, mainly in accident year 2017, driven by lower than expected reported loss activity.

2018
North America Commercial P&C Insurance experienced net favorable PPD of $610 million, representing 1.2 percent of the beginning consolidated net unpaid losses and loss expense reserves.
North America Personal P&C Insurance
2020
North America Personal P&C Insurance incurred net adverse PPD of $63 million, which was the net result of several underlying favorable and adverse movements, and was driven by the following principal changes:

•Net adverse development of $84 million in the homeowners product line, including valuables, mainly in accident years 2017 through 2019 due to higher than expected non-catastrophe loss emergence and adverse development arising from natural catastrophes in accident years 2017 and 2018; and

•Net favorable development of $22 million in the personal excess line, driven by favorable development mainly in the 2017 accident year, partially offset by adverse development in accident year 2019.

2019
North America Personal P&C Insurance incurred net favorable PPD of $95 million, which was the net result of several underlying favorable and adverse movements, and was driven by the following principal changes:

•Net favorable claim development of $132 million on the 2017 and 2018 natural catastrophes for all lines;

•Net favorable development of $26 million in our personal excess lines primarily impacting the 2016 accident year, due to lower than expected loss emergence and an increase in weighting towards experience-based methods, partly offset by adverse emergence in accident year 2015; and

•Net adverse development of $82 million in our homeowners lines, including valuables, arising from non-catastrophe loss emergence, mainly in the 2018 accident year.

2018
North America Personal P&C Insurance incurred net adverse PPD of $41 million, representing 0.1 percent of the beginning consolidated net unpaid losses and loss expense reserves.

North America Agricultural Insurance
North America Agricultural Insurance experienced net favorable PPD of $10 million, $80 million, and $110 million in 2020, 2019, and 2018, respectively. Actual claim development mainly relates to our Multiple Peril Crop Insurance business and was favorable due to better than expected crop yield results in certain states at the prior year-end period (i.e., 2020 results based on crop yield results at year-end 2019).

Overseas General Insurance
2020
Overseas General Insurance experienced net favorable PPD of $150 million which was the net result of several underlying favorable and adverse movements, and was driven by the following principal changes:

•Net favorable development of $49 million in long-tail business, primarily from:

•Net favorable development of $94 million in casualty lines, including favorable development of $143 million in accident years 2016 and prior, due to lower than expected loss emergence across primary and excess lines in Continental Europe, U.K., and Asia Pacific, partially offset by adverse development of $49 million in accident years 2017 through 2019, primarily due to adverse large loss experience in U.K. and Asia Pacific;

•Net favorable development of $22 million in political risk, driven by lower than expected loss emergence in accident years 2018 and 2019; and

•Net adverse development of $80 million in financial lines, with favorable development of $61 million in accident years 2015 and prior, primarily from favorable case-specific settlements within Continental Europe and Asia Pacific financial institutions, which was more than offset by adverse development of $141 million in accident years 2016 through 2019, primarily due to adverse large loss experience in D&O portfolios in the U.K. and Asia Pacific.

•Net favorable development of $101 million in short-tail business, primarily from:
•Net favorable development of $69 million in marine, driven by favorable loss emergence and claim-specific loss settlements across all regions in accident years 2012 through 2019; and

•Net favorable development of $21 million in A&H, driven by favorable development across Continental Europe, U.K. and Latin America primarily in accident years 2018 and 2019.

2019
Overseas General Insurance experienced net favorable PPD of $92 million, which was the net result of several underlying favorable and adverse movements, and was driven by the following principal changes:

•Net favorable development of $68 million in long-tail business, primarily from:

•Net favorable development of $101 million in casualty lines, including favorable development of $123 million in accident years 2015 and prior, due to lower than expected loss emergence mainly across primary lines in Continental Europe, U.K., and Asia Pacific, partially offset by adverse development of $22 million in accident years 2016 through 2018, primarily due to adverse attritional and large loss experience in Continental Europe; and

•Net adverse development of $52 million in financial lines, including adverse development of $127 million in accident years 2016 through 2018, primarily due to adverse large loss experience in D&O in the U.K. and Asia Pacific, offset by favorable development of $75 million in accident years 2015 and prior, due to lower than expected loss emergence across most regions in D&O and Professional Indemnity.

•Net favorable of $24 million in short-tail business, primarily from:

•Net favorable development of $45 million in A&H, driven by favorable development across Continental Europe, Latin America and Asia Pacific primarily in accident years 2017 and 2018;

•Net favorable development of $36 million in marine, driven by favorable loss emergence and claim-specific loss settlements across most regions and several accident years, including favorable liability emergence and litigation settlements in accident years 2016 and prior;

•Net adverse development of $23 million in construction, driven by adverse large loss experience in accident year 2018 for U.K. and Asia Pacific; and

•Net adverse development of $27 million in Surety, driven by adverse large loss experience across Continental Europe and Latin America in accident years 2017 and 2018.

2018
Overseas General Insurance experienced net favorable PPD of $212 million, representing 0.4 percent of the beginning consolidated net unpaid losses and loss expense reserves.

Global Reinsurance
2020
Global Reinsurance experienced net favorable PPD of $29 million, which was the net result of several underlying favorable and adverse movements, none of which is significant individually or in the aggregate.

2019
Global Reinsurance experienced net favorable PPD of $29 million, which was the net result of several underlying favorable and adverse movements, and was driven by the following principal changes:

•Net favorable development of $59 million in long-tail business, primarily in our auto, casualty, professional liability, medical malpractice, and workers’ compensation lines primarily from treaty years 2013 and prior principally due to lower than expected loss emergence; and

•Net adverse development of $30 million in short-tail business, which included $44 million of adverse development on 2017 and 2018 natural catastrophe events.
2018
Global Reinsurance experienced net favorable PPD of $50 million, representing 0.1 percent of the beginning consolidated net unpaid losses and loss expense reserves.

Corporate
2020
Corporate incurred adverse development of $433 million in long-tail lines, driven by the following principal changes:

•Adverse development of $254 million for U.S. child molestation claims, predominantly reviver statute-related;

•Adverse development of $106 million associated with asbestos and environmental liabilities, generally attributable to certain case specific incurred activity and higher than expected indemnity, expenses and defense costs on a limited number of accounts;

•Adverse development of $38 million on unallocated loss adjustment expenses due to run-off operating expenses paid and incurred in 2020 and $27 million from an increase in the provision for uncollectible reinsurance.
2019
Corporate incurred adverse development of $153 million in long-tail lines, driven by the following principal changes:

•Adverse development of $116 million driven principally by adverse development in asbestos and environmental liabilities due to the emergence of a limited number of excess accounts and somewhat greater than expected defense and indemnity costs (generally impacting larger modeled accounts); and

•Adverse development of $37 million on unallocated loss adjustment expenses due to run-off operating expenses paid and incurred in 2019.

2018
Corporate incurred adverse PPD of $45 million, representing 0.1 percent of the beginning consolidated net unpaid losses and loss expense reserves.

Asbestos and environmental (A&E)
Chubb's exposure to A&E claims principally arises out of liabilities acquired when it purchased Westchester Specialty in 1998, CIGNA's P&C business in 1999, and Chubb Corp in 2016. 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:
AsbestosEnvironmentalTotal
(in millions of U.S. dollars)GrossNetGrossNetGrossNet
Balance at December 31, 2017$1,621 $1,051 $607 $476 $2,228 $1,527 
Incurred activity136 75 101 (97)237 (22)(1)
Paid activity(265)(162)(83)104 (348)(58)
Balance at December 31, 20181,492 964 625 483 2,117 1,447 
Incurred activity129 70 46 28 175 98 (1)
Paid activity(162)(118)(142)(101)(304)(219)
Balance at December 31, 20191,459 916 529 410 1,988 1,326 
Incurred activity150 90 79 41 229 131 (1)
Paid activity(258)(133)(91)(72)(349)(205)
Balance at December 31, 2020$1,351 $873 $517 $379 $1,868 $1,252 
(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, 2020 and 2019 shown in the table above is comprised of:
December 31
(in millions of U.S. dollars)20202019
Brandywine operations$736 $754 
Westchester Specialty103 117 
Chubb Corp333 381 
Other, mainly Overseas General Insurance80 74 
Total$1,252 $1,326 

Brandywine Run-off entities – The Restructuring Plan and uncertainties relating to Chubb's ultimate Brandywine exposure

In 1996, the Pennsylvania Insurance Commissioner approved a plan to restructure INA Financial Corporation and its subsidiaries (the Restructuring) which included the division of Insurance Company of North America (INA) into two separate corporations:

(1) An active insurance company that retained the INA name and continued to write P&C business; and
(2) An inactive run-off company, now called Century Indemnity Company (Century).

As a result of the division, predominantly all A&E and certain other liabilities of INA were ascribed to Century and extinguished, as a matter of Pennsylvania law, as liabilities of INA.

As part of the Restructuring, most A&E liabilities of various U.S. affiliates of INA were reinsured to Century. Century and certain other run-off companies having A&E and other liabilities were contributed to Brandywine Holdings.

The U.S.-based Chubb INA companies assumed two contractual obligations in respect of the Brandywine operations in connection with the Restructuring: a surplus maintenance obligation in the form of the excess of loss (XOL) agreement and a dividend retention fund obligation.

XOL Agreement
In 1996, in connection with the Restructuring, a Chubb INA insurance subsidiary provided reinsurance coverage to Century in the amount of $800 million under an Aggregate Excess of Loss Reinsurance Agreement (XOL Agreement), triggerable if the statutory capital and surplus of Century falls below $25 million or if Century lacks liquid assets with which to pay claims as they become due.

Dividend Retention Fund
INA Financial Corporation established and funded a dividend retention fund (the Dividend Retention Fund) consisting of $50 million plus investment earnings. The full balance of the Dividend Retention Fund was contributed to Century as of December 31, 2002. Under the Restructuring Order, while any obligation to maintain the Dividend Retention Fund is in effect, to the extent dividends are paid by INA Holdings Corporation to its parent, INA Financial Corporation, and to the extent INA Financial Corporation then pays such dividends to INA Corporation, a portion of those dividends must be withheld to replenish the principal of the Dividend Retention Fund to $50 million. During 2020, 2019, 2018, 2011 and 2010, $250 million, $90 million, $50 million, $35 million and $15 million, respectively, were withheld from such dividends and deposited into the Dividend Retention Fund as a result of dividends paid up to the INA Corporation. Pursuant to a 2011 amendment to the Restructuring Order, capital contributions from the Dividend Retention Fund to Century are not required until the XOL Agreement has less than $200 million of capacity remaining on an incurred basis for statutory reporting purposes. The amount of the required capital contribution shall be the lesser of the amount necessary to restore the XOL Agreement remaining capacity to $200 million or the Dividend Retention Fund balance. In 2020 and 2019, capital contributions of $302 million and $64 million were made, respectively, from the Dividend Retention Fund to Century. The Dividend Retention Fund may not be terminated without prior written approval from the Pennsylvania Insurance Commissioner.

Effective December 31, 2004, Chubb INA contributed $100 million to Century in exchange for a surplus note. After giving effect to the contribution and issuance of the surplus note, the statutory surplus of Century at December 31, 2020 was $25 million and $573 million in statutory-basis losses have been ceded to the XOL Agreement on an inception-to-date basis. Century reports the amount ceded under the XOL Agreement in accordance with statutory accounting principles, which differ from GAAP
by, among other things, allowing Century to discount its liabilities, including certain asbestos related and environmental pollution liabilities and Century's reinsurance payable to active companies. For GAAP reporting purposes, intercompany reinsurance recoverables related to the XOL are eliminated upon consolidation.

While Chubb believes it has no legal obligation to fund Century losses above the XOL limit of coverage, Chubb's consolidated results would nevertheless continue to include any losses above the limit of coverage for so long as the Brandywine companies remain consolidated subsidiaries of Chubb.

Certain active Chubb companies are primarily liable for asbestos, environmental, and other exposures that they have reinsured to Century. Accordingly, if Century were to become insolvent and placed into rehabilitation or liquidation, some or all of the recoverables due to these active Chubb companies from Century could become uncollectible. At December 31, 2020 and 2019, the aggregate reinsurance recoverables owed by Century to certain active Chubb companies were approximately $1.6 billion and $1.5 billion, respectively, on an undiscounted basis. Chubb believes the active company intercompany reinsurance recoverables, which relate to direct liabilities payable over many years, are not impaired. At December 31, 2020 and 2019, Century's carried gross reserves (including reserves assumed from the active Chubb companies) were $2.1 billion and $1.8 billion, respectively. Should Century's loss reserves experience adverse development in the future and should Century be placed into rehabilitation or liquidation, the reinsurance recoverables due from Century to certain active Chubb companies would be payable only after the payment in full of certain expenses and liabilities, including administrative expenses and direct policy liabilities. Thus, the intercompany reinsurance recoverables would be at risk to the extent of the shortage of assets remaining to pay these recoverables.

Westchester Specialty – impact of NICO contracts on Chubb’s run-off entities

As part of the Westchester Specialty acquisition in 1998, NICO provided a 75 percent pro-rata share of $1.0 billion of reinsurance protection on losses and loss adjustment expenses incurred on or before December 31, 1996, in excess of a retention of $721 million. At December 31, 2020, the remaining unused incurred limit under the Westchester NICO agreement was $372 million.