For many exposures, especially those that can be considered long-tail, a particular accident or policy year may not have a sufficient volume of paid losses to produce a statistically reliable estimate of ultimate losses. In such a case, our actuaries typically assign more weight to the incurred development method than to the paid development method. As claims continue to settle and the volume of paid loss increases, the actuaries may assign additional weight to the paid development method. For most of our products, even the incurred losses for accident or policy years that are early in the claim settlement process will not be of sufficient volume to produce a reliable estimate of ultimate losses. In these cases, we may not assign much if any weight to the paid and incurred development methods. We may use the loss ratio, Bornhuetter-Ferguson and/or frequency times severity methods. For short-tail exposures, the paid and incurred development methods can often be relied on sooner, primarily because our history includes a sufficient number of years to cover the entire period over which paid and incurred losses are expected to change. However, we may also use the loss ratio, Bornhuetter-Ferguson and/or frequency times severity methods for short-tail exposures.
The table below summarizes the estimated pretax impact on our results of operations from various hypothetical revisions to our active life reserve assumptions. The annual GPV process involves updating all assumptions to the then current best estimate, and historically all significant assumptions have been revised each year. In the Hypothetical Revisions table below, we have assumed that revisions to such assumptions would occur in each policy type, age and duration within each policy group and would occur absent any changes, mitigating or otherwise, in the other assumptions. Although such hypothetical revisions are not currently required or anticipated, we believe they could occur based on past variances in experience and our expectations of the ranges of future experience that could reasonably occur. Any required increase in the recorded reserves resulting from the hypothetical revision in the table below would first reduce the margin in our carried reserves before it would affect results of operations. Any actual adjustment would be dependent on the specific policies affected and, therefore, may differ from the estimates summarized below. The estimated impacts to results of operations in the table below are after consideration of the existing margin.
The following table summarizes the gross and net carried reserves for Corporate & Other.
Insurance receivables include balances due currently or in the future, including amounts due from insureds related to losses under high deductible policies, and are presented at unpaid balances, net of an allowance for uncollectible receivables. Amounts are considered past due based on policy payment terms. The allowance is determined based on periodic evaluations of aged receivables, management's experience and current economic conditions. Insurance receivables and any related allowance are written off after collection efforts are exhausted or a negotiated settlement is reached.
Earnings (loss) per share is based on weighted average number of outstanding common shares. Basic earnings (loss) per share excludes the impact of dilutive securities and is computed by dividing Net income (loss) by the weighted average number of common shares outstanding for the period. Diluted earnings (loss) per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock.
components of net periodic pension cost to be presented outside of any subtotal of operating income. The ASU also stipulates that only the service cost component of net benefit cost is eligible for capitalization. The guidance is effective for interim and annual periods beginning after December 15, 2017. The guidance is to be applied on a prospective basis for capitalization of service costs and on a retrospective basis for the presentation of the service cost and other components of net periodic benefit costs in the Company's Consolidated Statements of Operations or in its disclosures. The Company will adopt the updated guidance effective January 1, 2018. The Company plans to expand the related footnote disclosure to show the amount of service cost and non-service cost components of net periodic benefit cost and the line items in the Consolidated Statements of Operations in which such amounts are reported. The adoption impact from the change is not expected to be material to the Company’s results of operations or financial position.
Net realized investment gains (losses) for the year ended December 31, 2017 included a $42 million loss related to the redemption of the Company's $350 million senior notes due November 2019.
As of December 31, 2017 and 2016, there were no unrecognized tax benefits.
As of December 31, 2017, the CNA Tax Group had no loss carryforwards or tax credit carryforwards.
In developing claim and claim adjustment expense (“loss” or “losses”) reserve estimates, our actuaries perform detailed reserve analyses that are staggered throughout the year. Every reserve group is reviewed at least once during the year. The analyses generally review losses gross of ceded reinsurance and apply the ceded reinsurance terms to the gross estimates to establish estimates net of reinsurance. In addition to the detailed analyses, we review actual loss emergence for all products each quarter. In developing the loss reserve estimates for property and casualty contracts, we generally project ultimate losses using several common actuarial methods as listed below. We review the various indications from the various methods and apply judgment to select an actuarial point estimate. The indicated required reserve is the difference between the selected ultimate loss and the inception-to-date paid losses. The difference between the selected ultimate loss and the case incurred or reported loss is IBNR. IBNR includes a provision for development on known cases as well as a provision for late reported incurred claims. Further, the Company does not establish case reserves for allocated loss adjustment expenses (ALAE), therefore ALAE reserves are included in our estimate of IBNR. The most frequently utilized methods to project ultimate losses include the following:
Bornhuetter-Ferguson using premiums and paid loss: The Bornhuetter-Ferguson using premiums and paid loss method is a combination of the paid development approach and the loss ratio approach. This method normally determines expected loss ratios similar to the approach used to estimate the expected loss ratio for the loss ratio method.
Favorable development for medical professional liability was primarily due to lower than expected severities for individual healthcare professionals, allied facilities and hospitals in accident years 2011 and prior and better than expected severity in medical products liability in accident years 2010 through 2015. This was partially offset by unfavorable development in accident years 2012 and 2013 related to higher than expected large loss emergence in hospitals and higher than expected frequency and severity in accident years 2014 and 2015 in our aging services business.
Favorable development for other coverages was due to better than expected claim frequency in property coverages provided to Specialty customers in accident year 2014.
In 2016, CNA adopted the Annual Performance Share Plan (PSP). The PSP provides officers with an opportunity to earn an award based upon attainment of specific performance goals achieved over a one-year performance period. Awards are granted at the beginning of each performance year and are generally subject to a two-year cliff vesting period after the Company’s annual performance has been determined. Prior to the PSP, CNA issued performance share units under the Long Term Incentive Plan (LTI Plan). The LTI Plan had a three-year performance period and continued to have outstanding awards through 2017. In both plans, the performance share units become payable within a range of 0% to 200% of the number of performance share units initially granted.
2017 Net realized investment gains (losses) includes a $42 million loss on the early redemption of the Company's $350 million senior notes due November 2019.