the fourth quarter of 2018. This product assists with logistics management and improved safety by tracking and scoring individual drivers based on driving attributes, including phone usage while the vehicle is in motion.
At December 31, 2019, our E&S casualty lines of business had recorded reserves, net of reinsurance, of $382 million, which represented 11% of our total net reserves. In 2019, this line experienced minimal unfavorable prior year reserve development . In 2018, this line experienced unfavorable prior year reserve development of $12.0 million, mostly associated with accident years 2015 and 2016. While we continue to build historical loss experience in this segment, our experience base is still significantly shorter than we have for our Standard Commercial Lines segment, therefore, our reserves for this line have greater uncertainty. In addition, by its nature, the composition of this book tends to undergo greater changes over time, which may impact development patterns.
Like all areas of our organization, our Claims Department is continually identifying areas for improvement and efficiency to increase their value proposition to our insureds and organization. These improvements may lead to changes in claims practices that affect average case reserve levels and claims settlement rates, which directly impact the data used to project ultimate loss and loss expense. While these changes increase the uncertainty in our estimates in the short term, we expect the longer-term benefit will be more refined management of the claims process.
The unfavorable prior year casualty reserve development in both years primarily related to our personal automobile book of business.
Over the past two-year period, we have taken steps to exit certain underperforming classes of E&S Lines business that had produced volatile results in the past, while entering into a new distribution relationship in April 2018. The decision to exit certain underperforming classes negatively impacted our NPW growth in 2019, but we expect it to help improve our underwriting results. Renewal pure price increases in E&S Lines averaged 4.0% in 2019, with substantially higher price increases in targeted classes. While the relatively small size of the book could lead to some volatility, improved underwriting, pricing, and claim outcomes have kept us on track to achieve our risk-adjusted profitability target for this segment.
We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (PCAOB), the Company's internal control over financial reporting as of December 31, 2019, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission, and our report dated February 12, 2020 expressed an unqualified opinion on the effectiveness of the Company’s internal control over financial reporting.
Evaluation of the estimate of reserve for loss and loss expense
We have designated substantially all of our fixed income securities portfolio as available-for-sale ("AFS"), with the remainder being designated as held-to-maturity ("HTM"), as we have the ability and positive intent to hold these securities to maturity. Our AFS securities are reported at fair value in our consolidated balance sheets, with unrealized gains or losses recognized in accumulated other comprehensive income (loss) ("AOCI"), net of tax. HTM securities are recorded at either: (i) amortized cost; or (ii) market value at the date of transfer into the HTM category, adjusted for subsequent amortization. After-tax
We will adopt this guidance on January 1, 2020 and it will not be material to our financial condition or results of operations. We will apply a modified retrospective approach for the adoption and we anticipate recording a cumulative-effect adjustment to the opening balance of 2020 retained earnings, which is not expected to be material. Also, as prescribed in the literature, we will not adjust the amortized cost basis of any securities for which we had previously recorded an OTTI charge. The cumulative-effect adjustment to increase retained earnings represents the net adjustment required to establish valuation allowances on our held-to-maturity ("HTM") debt securities and to re-estimate valuation allowances on our trade receivables and reinsurance recoverables under ASU 2016-13.
(f) The table below reflects the historical average annual percentage payout of incurred claims by age. For example, the general liability line of business averages payout of 6.3% of its ultimate losses in the first year, 12.5% in the second year, and so forth. The following is supplementary information about average historical claims duration as of December 31, 2019:
In computing the results of each segment, we do not make adjustments for interest expense or corporate expenses. We do not maintain separate investment portfolios for the segments and therefore, do not allocate assets to the segments.
We had a goodwill balance of $7.8 million at both December 31, 2019 and 2018 on our Consolidated Balance Sheet that relates to our Standard Commercial Lines reporting unit.
The use of derivative instruments is permitted under certain circumstances for the Pension Plan portfolio, but may not be used for unrelated speculative purposes or to create exposures that are not permitted in the Pension Plan's investment guidelines. Within the liability hedging assets, derivatives may be used to mitigate interest rate risk and reduce the interest duration mismatch between assets and liabilities of the Pension Plan to help insulate the funded status of the plan. We currently invest in a U.S. Treasury overlay derivative strategy, within the funds in our liability hedging assets, to manage the interest rate duration mismatch between the assets and liabilities of the Pension Plan. Considering the impact of this derivative overlay, the liability hedging assets provide for an approximate 57% hedge against the projected benefit obligation.
As part of our overall investment diversification, we invest in various BlackRock funds from time to time. These funds accounted for less than 1% of our invested assets at December 31, 2019 and December 31, 2018, and are predominately reflected in Equity securities on our Consolidated Balance Sheet. During 2019, with regard to BlackRock funds, we (i) purchased $21.7 million, (ii) sold $59.5 million, (iii) recognized a $5.7 million net realized and unrealized gain, and (iv) recorded $0.8 million in income. During 2018, we purchased $41.4 million in securities and recognized net realized and unrealized losses of $3.6 million. There were no material transactions related to these holdings in 2017. There were no amounts payable on the settlement of these investment transactions at December 31, 2019, December 31, 2018, or December 31, 2017.
(a) We purchase annuities from life insurance companies to fulfill obligations under claim settlements that provide for periodic future payments to claimants. As of December 31, 2019, we had purchased such annuities with a present value of $25.5 million for settlement of claims on a structured basis for which we are contingently liable. To our knowledge, there are no material defaults from any of the issuers of such annuities.