We maintain non-contributory defined benefit pension plans for many of our employees. In addition, we maintain postretirement health care and life insurance plans for our retirees and their dependents, which are both contributory and non-contributory, and include a limit on our share of the cost for certain recent and future retirees. In accordance with our accounting policy for pension and other postretirement benefits, operating expenses include pension and benefit related credits and/or charges based on actuarial assumptions, including projected discount rates and an estimated return on plan assets. These estimates are updated in the fourth quarter or upon a remeasurement event to reflect actual return on plan assets and updated actuarial assumptions. The adjustment will be recognized in the income statement during the fourth quarter or upon a remeasurement event pursuant to our accounting policy for the recognition of actuarial gains and losses.

Net Periodic Cost

The following table summarizes the benefit (income) cost related to our pension and postretirement health care and life insurance plans:

Severance Payments

During the three months ended March 31, 2015, we paid severance benefits of $0.3 billion. At March 31, 2015, we had a remaining severance liability of $0.6 billion, a portion of which includes future contractual payments to employees separated as of March 31, 2015.

Employer Contributions

During the three months ended March 31, 2015, we contributed $0.3 billion to our other postretirement benefit plans and $0.2 billion to our qualified pension plans. The contributions to our nonqualified pension plans were not material during the three months ended March 31, 2015. There have been no material changes with respect to the qualified and nonqualified pension contributions in 2015 as previously disclosed in Part II. Item 7. “Management’s Discussion and Analysis of Financial Condition and Results of Operations” in our Annual Report on Form 10-K for the year ended December 31, 2014.