to pay current benefits and other cash obligations of the plan. This is achieved by investing in a globally diversified mix of public and private equity, fixed income, real assets, hedge funds, and other assets and instruments. Our expected long-term rate of return on assets for net periodic pension benefit cost for the year ended December 31, 2014 was 9% .  

 

Life Expectancy . We have historically utilized the Society of Actuaries' ("SOA") published mortality data in developing a best estimate of life expectancy. On October 27, 2014, the SOA published updated mortality tables for U.S. plans and an updated improvement scale, which both reflect improved longevity. Based on an evaluation of these new tables and our perspective of future longevity, we updated the mortality assumptions for purposes of measuring pension and other postretirement and postemployment benefit obligations at December 31, 2014 . The improvement in life expectancy increases our benefit obligations and future expense as benefit payments are paid over an extended period of time.  

 

Funding. Our funding obligations for qualified defined benefit plans are governed by the Employee Retirement Income Security Act. The Pension Protection Act of 2006 allows commercial airlines to elect alternative funding rules (“Alternative Funding Rules”) for defined benefit plans that are frozen. Delta elected the Alternative Funding Rules under which the unfunded liability for a frozen defined benefit plan may be amortized over a fixed 17-year period and is calculated using an 8.85% discount rate.  

 

While the Pension Protection Act makes our funding obligations for these plans more predictable, factors outside our control continue to have an impact on the funding requirements. Estimates of future funding requirements are based on various assumptions and can vary materially from actual funding requirements. Assumptions include, among other things, the actual and projected market performance of assets; statutory requirements; and demographic data for participants. For additional information, see Note 11 of the Notes to the Consolidated Financial Statements.  

 

Recent Accounting Standards  

 

Revenue from Contracts with Customers  

 

In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, "Revenue from Contracts with Customers." While the standard supersedes existing revenue recognition guidance, it closely aligns with current GAAP. Under the new standard, revenue is recognized at the time a good or service is transferred to a customer for the amount of consideration received for that specific good or service. It is effective for annual reporting periods beginning after December 15, 2016, including interim reporting periods, and early adoption is not permitted. Entities may use a full retrospective approach or report the cumulative effect as of the date of adoption. We are currently evaluating the impact, if any, the adoption of this standard will have on our Consolidated Financial Statements.  

 

Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income  

 

In February 2013, the FASB issued