the following tables present a reconciliation of the beginning and ending balances of the fair value measurements using significant unobservable inputs ( level 3 ) for 2015 and 2014 , respectively: .
what was the growth rate in the account balance 2015
purchases , issuances and settlements , net . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 balance as of december 31 , 2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ 127 the company 2019s other postretirement benefit plans are partially funded and the assets are held under various trusts . the investments and risk mitigation strategies for the plans are tailored specifically for each trust . in setting new strategic asset mixes , consideration is given to the likelihood that the selected asset allocation will effectively fund the projected plan liabilities and the risk tolerance of the company . the company periodically updates the long-term , strategic asset allocations and uses various analytics to determine the optimal asset allocation . considerations include plan liability characteristics , liquidity characteristics , funding requirements , expected rates of return and the distribution of returns . in june 2012 , the company implemented a de-risking strategy for the medical bargaining trust within the plan to minimize volatility . as part of the de-risking strategy , the company revised the asset allocations to increase the matching characteristics of assets relative to liabilities . the initial de-risking asset allocation for the plan was 60% ( 60 % ) return-generating assets and 40% ( 40 % ) liability-driven assets . the investment strategies and policies for the plan reflect a balance of liability driven and return-generating considerations . the objective of minimizing the volatility of assets relative to liabilities is addressed primarily through asset 2014liability matching , asset diversification and hedging . the fixed income target asset allocation matches the bond-like and long-dated nature of the postretirement liabilities . assets are broadly diversified within asset classes to achieve risk-adjusted returns that in total lower asset volatility relative to the liabilities . the company assesses the investment strategy regularly to ensure actual allocations are in line with target allocations as appropriate . strategies to address the goal of ensuring sufficient assets to pay benefits include target allocations to a broad array of asset classes and , within asset classes strategies are employed to provide adequate returns , diversification and liquidity . the assets of the company 2019s other trusts , within the other postretirement benefit plans , have been primarily invested in equities and fixed income funds . the assets under the various other postretirement benefit trusts are invested differently based on the assets and liabilities of each trust . the obligations of the other postretirement benefit plans are dominated by obligations for the medical bargaining trust . thirty-nine percent and four percent of the total postretirement plan benefit obligations are related to the medical non-bargaining and life insurance trusts , respectively . because expected benefit payments related to the benefit obligations are so far into the future , and the size of the medical non-bargaining and life insurance trusts 2019 obligations are large compared to each trusts 2019 assets , the investment strategy is to allocate a significant portion of the assets 2019 investment to equities , which the company believes will provide the highest long-term return and improve the funding ratio . the company engages third party investment managers for all invested assets . managers are not permitted to invest outside of the asset class ( e.g . fixed income , equity , alternatives ) or strategy for which they have been appointed . investment management agreements and recurring performance and attribution analysis are used as tools to ensure investment managers invest solely within the investment strategy they have been provided . futures and options may be used to adjust portfolio duration to align with a plan 2019s targeted investment policy. .