Investments	12 Months Ended
Dec. 31, 2018
Investments
Investments	7. Investments As of December 31, 2018 and 2017, our investments consisted of U.S. Treasury securities, maturing at various dates through January 2019. Investments are classified as short- or long-term investments on our consolidated balance sheets based on maturity. U.S. Treasury securities are classified as available-for-sale and are recorded at amortized cost. As of December 31, 2018, our one U.S. Treasury security was in an unrealized loss position. While this security has been in an unrealized loss position for more than 12 months, the security matured in January 2019 and we recovered the full amortized cost basis. Accordingly, we believe that there was no other-than-temporary impairment as of December 31, 2018. Total amortized cost and fair value each were $5.0 million as of December 31, 2018, with an unrealized loss of $1 thousand. Total amortized cost and fair value were $24.9 million and $24.8 million as of December 31, 2017, respectively, with a combined unrealized loss of $96 thousand.

7. Investments

As of December 31, 2018 and 2017, our investments consisted of U.S. Treasury securities, maturing at various dates through January 2019. Investments are classified as short- or long-term investments on our consolidated balance sheets based on maturity. U.S. Treasury securities are classified as available-for-sale and are recorded at amortized cost.

As of December 31, 2018, our one U.S. Treasury security was in an unrealized loss position. While this security has been in an unrealized loss position for more than 12 months, the security matured in January 2019 and we recovered the full amortized cost basis. Accordingly, we believe that there was no other-than-temporary impairment as of December 31, 2018. Total amortized cost and fair value each were $5.0 million as of December 31, 2018, with an unrealized loss of $1 thousand. Total amortized cost and fair value were $24.9 million and $24.8 million as of December 31, 2017, respectively, with a combined unrealized loss of $96 thousand.