Quarterly report pursuant to Section 13 or 15(d)

Short Term Investments

Short Term Investments
9 Months Ended
Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]  
Short Term Investment
Short Term Investments
The following table summarizes the available-for-sale investments held as of September 30, 2018. There were no available-for-sale investments in prior periods.

September 30, 2018
U.S. government agency securities and treasuries
The amortized cost of the available-for-sale investments is adjusted for amortization of premiums and accretion of discounts to maturity. There were no material realized gains or losses recognized on the sale or maturity of available-for-sale investments during the three or nine months ended September 30, 2018.