5. CASH, CASH EQUIVALENTS AND AVAILABLE-FOR-SALE SECURITIES

        Cash, cash equivalents and available-for-sale securities consist of the following (in thousands):

        Cash equivalents and available-for-sale securities included the following securities with unrealized gains and losses (in thousands):

        As of December 31, 2013, the contractual maturities of our cash equivalents and available-for-sale securities were (in thousands):

        As of December 31, 2013, our cash equivalents and available-for-sale securities had a weighted-average time to maturity of approximately 159 days. We view our available-for-sale portfolio as available for use in current operations. Accordingly, we have classified certain investments as available-for-sale securities on our balance sheet even though the stated maturity date of these securities may be more than one year from the current balance sheet date. We have the ability to hold all investments as of December 31, 2013 through their respective maturity dates. In the second quarter of 2013, we sold certain available-for-sale securities at their approximate carrying values prior to maturity and received proceeds of $16.5 million. At December 31, 2013, we had 4 investments in continuous unrealized loss position for more than twelve months, which will mature on February 10, 2014. The total unrealized loss for these investments is approximately $2,000, which is immaterial. At December 31, 2012, we had no investments that had been in a continuous unrealized loss position for more than twelve months. As of December 31, 2013, a total of 12 individual securities had been in an unrealized loss position for twelve months or less and the losses were deemed to be temporary.

        The following table shows the fair value and gross unrealized losses of our investments in individual securities that are in an unrealized loss position, aggregated by investment category (in thousands):