Cash and Cash Equivalents

6 Months Ended

Jun. 30, 2018

Cash And Cash Equivalents [Abstract]

Cash and Cash Equivalents

5. Cash and Cash Equivalents

The Company considers all highly liquid investments with original maturity from the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include bank demand deposits and money market funds that invest primarily in U.S. government-backed securities and treasuries. Cash equivalents are carried at cost, which approximates their fair value.