customer attrition, and royalty rates, each of which have a significant impact on the estimated fair values. Though management considers its judgments and assumptions to be reasonable, changes in these assumptions could impact the estimated fair value.
In completing our goodwill impairment testing in the fourth quarter of 2015, the estimated fair value of all reporting units substantially exceeded carrying value except for our ONG reporting unit, which exceeded its carrying value by 14 percent. Our financial plan for 2016 anticipated the beginning of a recovery in oil and natural gas markets that would drive improved ONG performance in the second half of the year. After considering third quarter 2016 operating results and preliminary projections from our 2017 planning process, we concluded that the depth and length of industry weakness, and its continuing impact on ONG results, were greater than previously expected. At the end of the third quarter we initiated an impairment analysis. We completed the analysis in the fourth quarter and recorded adjustments to reduce goodwill by $147 million and other intangible assets by $45 million. The non-cash impairment charges reduced operating earnings by $192 million, created a $31 million deferred tax benefit, and decreased net earnings by $161 million.
We completed our annual impairment testing of goodwill and other intangible assets in the fourth quarter of 2016. No further impairment charges were recorded as a result of that review.
Income Taxes. In the preparation of the Company’s consolidated financial statements, management calculates income taxes. This includes estimating current tax liability as well as assessing temporary differences resulting from different treatment of items for tax and financial statement purposes. These differences result in deferred tax assets and liabilities, which are recorded on the balance sheet using statutory rates in effect for the year in which the differences are expected to reverse. These assets and liabilities are analyzed regularly and management assesses the likelihood that deferred tax assets will be recoverable from future taxable income. A valuation allowance is established to the extent that management believes that recovery is not likely. Liabilities for uncertain tax positions are also established for potential and ongoing audits of federal, state and international issues. The Company routinely monitors the potential impact of such situations and believes that liabilities are properly stated. Valuations related to amounts owed and tax rates could be impacted by changes to tax codes, changes in statutory rates, the Company’s future taxable income levels and the results of tax audits.
Retirement Obligations. The measurements of the Company’s pension and postretirement medical obligations are dependent on a number of assumptions including estimates of the present value of projected future payments, taking into consideration future events such as salary increase and demographic experience. These assumptions may have an impact on the expense and timing of future contributions.
The assumptions used in developing the required estimates for pension obligations include discount rate, inflation, salary increases, retirement rates, expected return on plan assets and mortality rates. The assumptions used in developing the required estimates for postretirement medical obligations include discount rates, rate of future increase in medical costs and participation rates.
For U.S. plans, the Company establishes its discount rate assumption by reference to a yield curve published by an actuary and projected plan cash flows. For plans outside the U.S., the Company establishes a rate by country by reference to highly rated corporate bonds. These reference points have been determined to adequately match expected plan cash flows. The Company bases its inflation assumption on an evaluation of external market indicators. The salary assumptions are based on actual historical experience, the near-term outlook and assumed inflation. Retirement rates are based on experience. The investment return assumption is based on the expected long-term performance of plan assets. In setting this number, the Company considers the input of actuaries and investment advisors, its long-term historical returns, the allocation of plan assets and projected returns on plan assets. The Company decreased its investment return assumption for its U.S. plan to 7.3 percent for 2017. Mortality rates are based on current common group mortality tables for males and females.
In 2016, net pension cost of $15 million was allocated to cost of products sold and operating expenses based on salaries and wages. At December 30, 2016, a one-half percentage point decrease in the indicated assumptions would have the following effects (in millions):
Expected return on assets
Recent Accounting Pronouncements
Refer to Note A (Summary of Significant Accounting Policies) to the Consolidated Financial Statements of this Form 10-K for disclosures related to recent accounting pronouncements.