We believe we will continue to be competitive in the life and annuity markets through our broad line of products, diverse distribution channels, and consistent high level of customer service. We modify our products to meet customer needs and to expand our reach where we believe we can obtain profitable growth.
GAAP requires us to evaluate the recoverability of our deferred tax assets and establish a valuation allowance, if necessary, to reduce our deferred tax asset to an amount that is more-likely-than-not to be realized. Considerable judgment is required in determining whether a valuation allowance is necessary, and if so, the amount of such valuation allowance. Although realization is not assured, management believes it is more-likely-than-not that the deferred tax assets will be realized and that no valuation allowance is necessary.
Bonds-We allocate most of our fixed maturity securities to support our insurance business. At December 31, 2015, our fixed maturity securities had an estimated fair value of $13.2 billion, which was $0.2 billion, or 1.6%, above amortized cost. At December 31, 2014, our fixed maturity securities had an estimated fair value of $13.6 billion, which was $0.7 billion, or 5.1%, above amortized cost. Fixed maturity securities’ estimated fair value, due in one year or less, decreased from $1.3 billion as of December 31, 2014 to $0.5 billion as of December 31, 2015, primarily as a result of maturities.
Net realized gains increased $39.3 million during 2015 compared to 2014 due to the sale of equity securities. Net realized gains decreased $76.1 million during 2014 compared to 2013 primarily as a result of very strong markets for the type and location of investment real estate sold in 2013. Other-than-temporary impairment on investment securities increased $21.3 million during 2015 compared to 2014 primarily relating to equity securities in the energy and utility sectors. Other-than-temporary impairment on investment securities increased $2.1 million during 2014 compared to 2013.
Participating business comprised approximately 6.7% of the life insurance in-force at December 31, 2015 and 19.6% of life premiums in 2015. Of the total participating business, 77.8% was written by Farm Family Life Insurance Company (“Farm Family Life”). For the participating business excluding Farm Family Life, the allocation of dividends to participating policyowners is based upon a comparison of experienced rates of mortality, interest and expenses, as determined periodically for representative plans of insurance, issue ages and policy durations, with the corresponding rates assumed in the calculation of premiums.
In February 2015, the FASB issued guidance amending the consolidation analysis. The guidance modifies the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities. The guidance eliminates the presumption that a general partner should consolidate a limited partnership and affects the consolidation analysis of reporting entities that are involved with VIEs. The amended guidance is effective for reporting periods beginning after December 15, 2015. The impact of the adoption is not expected to be material to the Company’s financial statements.
Index to Financial Statements Note 9 - Fair Value of Financial Instruments