During 2016, we realized pretax investment gains, net of losses, of $215 million ($140 million after-tax) from sales and redemptions of securities. These net gains were primarily related to foreign currency gains on sale and redemption activities as well as gains related to call activity on previously impaired securities. We realized pretax investment losses of $83 million ($54 million after-tax) as a result of the recognition of other-than-temporary impairment losses on certain securities.
Our Reconciliation of Net Earnings to Operating Earnings table above includes a line item related to the costs incurred in using foreign currency forward contracts to hedge a portion of the foreign currency exchange risk on the U.S. dollar-denominated assets in Aflac Japan's investment portfolio. These hedge costs are derived from the difference between the foreign currency spot rate at time of trade inception and the contractual foreign currency forward rate. For our non-U.S. GAAP reporting disclosures, we have historically reported the total hedge costs of these contracts in the period in which the foreign currency forward was executed. Beginning in 2016, we changed our non-U.S. GAAP reporting for these hedge costs by amortizing them evenly over the life of the foreign currency forward contracts. We believe amortizing the hedge costs over the life of these contracts provides a better measure of our non-U.S. GAAP results as compared to our historical methodology. In 2016, we began increasing the duration of the foreign currency forward contracts used to hedge our U.S. dollar-denominated assets in Aflac Japan's investment portfolio to cover periods extending beyond one year. Therefore, recognizing these costs over the extended hedging periods provides a better measure of our costs, and better reflects the economics of how hedge costs emerge over the life of the hedge. The table below summarizes the impact of our change in hedge cost reporting methodology:
Under state insurance guaranty association laws and similar laws in international jurisdictions, we are subject to assessments, based on the share of business we write in the relevant jurisdiction, for certain obligations of insolvent insurance companies to policyholders and claimants. In the United States, some states permit member insurers to recover assessments paid through full or partial premium tax offsets. The Company's policy is to accrue assessments when the entity for which the insolvency relates has met its state of domicile's statutory definition of insolvency, the amount of the loss is reasonably estimable and the related premium upon which the assessment is based is written. In most states, the definition is met with a declaration of financial insolvency by a court of competent jurisdiction.
The ratings of our securities referenced in the table below are based on the ratings designations provided by major NRSROs (Moody's, S&P and Fitch) or, if not rated, are determined based on our internal analysis of such securities. For investment-grade securities where the ratings assigned by the major credit agencies are not equivalent, we use the second lowest rating that is assigned. For a description of the ratings methodology that we use when a security is below investment grade or split-rated, see "Investments, Below-Investment-Grade and Split-Rated Securities" in the Analysis of Financial Condition section of this MD&A.
Generally, declines in fair values can be a result of changes in interest rates, yen/dollar exchange rate, and changes in net spreads driven by a broad market move or a change in the issuer's underlying credit quality. At times in 2016, market volatility was at elevated levels, especially in the energy and commodity-related sectors. As we believe these issuers have the ability to continue making timely payments of principal and interest, we view these changes in fair value to be temporary and do not believe it is necessary to impair the carrying value of these securities. See the Unrealized Investment Gains and Losses section in Note 3 of the Notes to the Consolidated Financial Statements for further discussions of unrealized losses related to financial institutions, including perpetual securities, and other corporate investments.
The 2016 referendum in the United Kingdom (UK) in favor of the UK withdrawing from the European Union (EU) (Brexit) has added a new level of uncertainty to Europe’s economic recovery, although financial markets have stabilized after initially reacting to Brexit with increased volatility. We cannot estimate the ultimate impact of Brexit, which may include changes to the economies of the UK and other EU countries, policy action by the UK government, the Bank of England, the EU, or the ECB, or an increase in economic isolationism throughout Europe and the rest of the world.
Our primary exposure to be hedged is our investment in Aflac Japan, which is affected by changes in the yen/dollar exchange rate. To mitigate this exposure, we have taken several courses of action. First, Aflac Japan maintains certain unhedged U.S. dollar-denominated securities, which serve as an economic currency hedge of a portion of our investment in Aflac Japan. Second, we have designated the majority of the Parent Company’s yen-denominated liabilities (Samurai and Uridashi notes) as non-derivative hedging instruments and certain foreign currency forwards and options as derivative hedges of our net investment in Aflac Japan. We make our net investment hedge designation at the beginning of each quarter. If the total of the designated Parent Company non-derivative and derivatives notional is equal to or less than our net investment in Aflac Japan, the hedge is deemed to be effective, and the exchange effect on the yen-denominated liabilities and the change in estimated fair value of the derivatives are reported in the unrealized foreign currency component of other comprehensive income. We estimate that if the designated net investment hedge positions exceeded our net investment in Aflac Japan by 10 billion yen, we would report a foreign exchange gain/loss of approximately $1 million for every 1% yen weakening/strengthening in the end-of-period yen/dollar exchange rate. Our net investment hedge was effective during the years ended December 31, 2016, 2015 and 2014, respectively.
(1) Aflac Japan’s policy liabilities increased 3.6% in yen during the year ended December 31, 2016.
obtain the underlying collateral, nor do we have control over the instruments in the VIEs, unless there is an event of default. For those entities where we are the primary beneficiary, the assets consolidated are fixed-maturity securities, perpetual securities, equity securities, and derivative instruments; collateral consisting of these asset classes is reported separately with the caption "- consolidated variable interest entities" on our balance sheet.
Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments: In August 2016, the FASB issued amendments that provide guidance on eight specific statement of cash flows classification issues. The amendments are effective for public companies for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted for any interim or annual period. The adoption of this guidance is not expected to have a significant impact on our financial position, results of operations, disclosures, or statements of cash flows.
Revenue from Contracts with Customers: In May 2014, the FASB issued updated guidance that affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards (e.g., insurance contracts or lease contracts). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, the FASB deferred the effective date for this standard to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. Other updates related to the new guidance, which are effective as of the same reporting period, pertain to improvements in certain areas. Earlier application is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods. We have identified revenue in scope of this guidance to include certain revenues associated with affiliated entities in support of our operations. We estimate the revenue within scope of the guidance to represent less than 1% of our total revenues as of December 31, 2016. We estimate that the adoption of this guidance will not have a significant impact on our financial position, results of operations and disclosures.
The unrealized losses on our fixed income or perpetual securities investments have been primarily related to general market changes in interest rates, foreign exchange rates, and/or the levels of credit spreads rather than specific concerns with the issuer's ability to pay interest and repay principal. The unrealized losses on our investments in equity securities are primarily related to foreign exchange rates, general market conditions which reflect prospects for the economy as a whole, or specific information pertaining to an industry or an individual company.
At December 31, 2016, debt securities with a fair value of $17 million were on deposit with regulatory authorities in the United States (including U.S. territories) and Japan. We retain ownership of all securities on deposit and receive the related investment income.
these derivatives and the related hedged items in current earnings within derivative and other gains (losses). The change in the fair value of the interest rate swaptions related to the time value of the option is excluded from the assessment of hedge effectiveness.
The following table summarizes the impact to realized investment gains (losses) and other comprehensive income (loss) from all derivatives and hedging instruments for the years ended December 31.
Collateral posted by us to third parties for derivative transactions can generally be repledged or resold by the counterparties. The aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a net liability position by counterparty was approximately $1.2 billion and $26 million as of December 31, 2016 and 2015, respectively. We are generally allowed to sell or repledge collateral obtained from our derivative counterparties, although we do not typically exercise such rights. (See the Offsetting tables below for collateral posted or received as of the reported balance sheet dates.)
The significant drivers of the valuation of the interest and foreign exchange swaps are interest rates, foreign exchange rates and CDS spreads. Our swaps have long maturities that increase the sensitivity of the swaps to interest rate fluctuations. Since most of our yen-denominated cross currency swaps are in a net liability position, an increase in interest rates will decrease the liabilities and increase the value of the swap.
In March 2015, the Parent Company issued two series of senior notes totaling $1.0 billion through a U.S. public debt offering. The first series, which totaled $550 million, bears interest at a fixed rate of 2.40% per annum, payable semi-
Share Repurchase Program: During 2016, we purchased 21.6 million shares of our common stock in the open market, compared with 21.2 million shares in 2015 and 19.7 million shares in 2014. As of December 31, 2016, a remaining balance of 26.8 million shares of our common stock was available for purchase under share repurchase authorizations by our board of directors.
We have funded defined benefit plans in Japan and the United States, however the U.S. plan was frozen to new participants effective October 1, 2013. We also maintain non-qualified, unfunded supplemental retirement plans that