Investments	3 Months Ended
Mar. 31, 2018
Investments
Investments	7. Investments As of March 31, 2018, our investments consisted of U.S. Treasury securities, maturing at various dates through January 2019. These securities are classified as short-term investments on our consolidated balance sheets based on maturity and are classified as available-for-sale and are recorded at fair value. As of March 31, 2018, all five of our U.S. Treasury securities were in an unrealized loss position, none of which had been in an unrealized loss position for 12 months or greater. Total amortized cost and fair value were $24.9 million and $24.8 million, respectively, as of March 31, 2018. Based on review of these securities, we believe that the cost basis of these available-for-sale securities is recoverable and that there were no other-than-temporary impairments on these securities as of March 31, 2018.

7. Investments

As of March 31, 2018, our investments consisted of U.S. Treasury securities, maturing at various dates through January 2019. These securities are classified as short-term investments on our consolidated balance sheets based on maturity and are classified as available-for-sale and are recorded at fair value.

As of March 31, 2018, all five of our U.S. Treasury securities were in an unrealized loss position, none of which had been in an unrealized loss position for 12 months or greater. Total amortized cost and fair value were $24.9 million and $24.8 million, respectively, as of March 31, 2018. Based on review of these securities, we believe that the cost basis of these available-for-sale securities is recoverable and that there were no other-than-temporary impairments on these securities as of March 31, 2018.