(10) Investments

     Auction Rate Certificates

          Auction rate certificates are long-term securities structured to reset their coupon rates by means of an auction. We accounted for our investment in auction rate certificates as available-for-sale securities. In January 2010, our investment in the auction rate certificates was called by the issuer at par plus accrued interest, or $9,456, resulting in a gain of $425 in the six months ended June 30, 2010.

     Restricted Investments

          Restricted investments relate to reimbursement obligations under letters of credit issued for the benefit of lessors of office space. As of June 30, 2011 and December 31, 2010, our Long-term restricted investments were $3,146 and $3,396, respectively. During the three months ended June 30, 2011, $250 of obligations relating to these letters of credit were terminated.