3.Cash, Cash Equivalents and Investments

Cash, cash equivalents and investments consisted of the following:

Our short-term investments have maturities of less than twelve months and are classified as available-for-sale. Our long-term investments have maturities of greater than twelve months and are classified as available-for-sale.

The following tables summarize our available-for-sale securities’ adjusted cost, gross unrealized gains, gross unrealized losses and fair value by significant investment category as of December 31, 2013 and June 30, 2014.

The following table presents available-for-sale investments by contractual maturity date as of December 31, 2013 and June 30, 2014.

Our investment policy requires investments to be investment grade, primarily rated “A1” by Standard & Poor’s or “P1” by Moody’s or better for short-term investments and rated “A” by Standard & Poor’s or “A2” by Moody’s or better for long-term investments, with the objective of minimizing the potential risk of principal loss. In addition, the investment policy limits the amount of credit exposure to any one issuer.

The unrealized losses on our available-for-sale securities as of June 30, 2014 were primarily a result of unfavorable changes in interest rates subsequent to the initial purchase of these securities. As of June 30, 2014, we owned 98 securities that were in an unrealized loss position. We do not intend nor expect to need to sell these securities before recovering the associated unrealized losses. We expect to recover the full carrying value of these securities. As a result, no portion of the unrealized losses at June 30, 2014 is deemed to be other-than-temporary and the unrealized losses are not deemed to be credit losses. No available-for-sale securities have been in an unrealized loss position for twelve months or more. When evaluating the investments for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer and any changes thereto, and our intent to sell, or whether it is more likely than not we will be required to sell, the investment before recovery of the investment’s amortized cost basis. During the three and six months ended June 30, 2014, we did not recognize any impairment charges.