Fair Value of Investments and Other-Than-Temporary Impairments
As described in Note 2 to the financial statements in Item 8 of this Report, we estimate the fair value of our available-for-sale debt and equity securities each quarter. Available-for-sale debt securities consist of cash equivalents, municipal bonds, U.S. treasury securities, U.S. agency securities, corporate notes, and municipal auction rate securities. Available-for-sale equity securities consist of shares of a single publicly traded company. Fair value is defined as the price that would be received from the sale of an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. When identical or similar assets are traded in active markets, the level of judgment required to estimate their fair value is relatively low. This is generally true for our cash equivalents and our corporate equity securities, which we consider to be Level 1 assets, and our municipal bonds, U.S. agency securities and corporate notes, which we consider to be Level 2 assets. We measure the fair values of our Level 2 investments with the help of a pricing service that either provides quoted market prices in active markets for identical or similar securities or uses observable inputs for their pricing without applying significant adjustments. Our fair value processes include controls that are designed to ensure that we record appropriate fair values for our Level 2 investments. These controls include comparison to pricing provided by a secondary pricing service or investment manager, validation of pricing sources and models, review of key model inputs, analysis of period-over-period price fluctuations, and independent recalculation of prices where appropriate. Significant judgment is required to estimate the fair value of assets and liabilities when observable inputs are not available (Level 3). For example, we use a discounted cash flow model to estimate the fair value of our municipal auction rate securities because we have determined that the market for those securities is inactive. At
July 31, 2013, we held a total of $33 millionin municipal auction rate securities, which was not significant compared with total available-for-sale debt securities of $860 millionat that date. We record unrealized gains and losses on our available-for-sale securities, net of income taxes, in other comprehensive income in the equity section of our balance sheet until the security is sold or we determine that the decrease in fair value is other-than-temporary. We consider a number of factors in determining whether to recognize an impairment charge, including the reason for the decrease in fair value, the severity of the decrease in fair value, the length of time that the fair value has been less than the cost basis of the security, the financial condition and near-term prospects of the issuer, and whether we intend to sell or may be required to sell the security before anticipated recovery of our cost basis. Changes in our estimates of the fair values of our available-for-sale securities may result in material increases or decreases in our net income in the period in which the change occurs.
As described in "Description of Business and Summary of Significant Accounting Policies - Business Combinations," in Note 1 to the financial statements in Item 8 of this Report, under the acquisition method of accounting we generally recognize the identifiable assets acquired, the liabilities assumed, and any noncontrolling interests in an acquiree at their fair values as of the date of acquisition. We measure goodwill as the excess of consideration transferred, which we also measure at fair value, over the net of the acquisition date fair values of the identifiable assets acquired and liabilities assumed. The acquisition method of accounting requires us to exercise judgment and make significant estimates and assumptions regarding the fair values of the elements of a business combination as of the date of acquisition, including the fair values of identifiable intangible assets, deferred tax asset valuation allowances, liabilities related to uncertain tax positions, and contingencies. This method also requires us to refine these estimates over a one-year measurement period to reflect new information obtained about facts and