Loan Agreement and Warrant to Purchase Preferred Stock	12 Months Ended
Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Loan Agreement and Warrant to Purchase Preferred Stock	7. Loan Agreement and Warrant to Purchase Preferred Stock On June 23, 2017, the Company entered into the Loan Agreement with a lender, which provided for the issuance of term loans of up to $10,000, subject to the achievement of various development and corporate milestones. Any outstanding principal amounts under the Loan Agreement accrued interest at a floating per annum rate equal to the greater of 1% and the “prime rate,” as defined in the Loan Agreement, minus 3%. The Loan Agreement contained customary indemnification obligations and customary events of default. In the event of default by the Company under the Loan Agreement, the lender would be entitled to exercise their remedies thereunder, including the right to accelerate the debt, upon which the Company may be required to repay all amounts then outstanding under the Loan Agreement or the lender may take possession of the collateral securing the Loan Agreement. The Loan Agreement also includes certain restrictions on, among other things, the Company’s ability to incur additional indebtedness, change the name or location of its business, merge with or acquire other entities, pay dividends or make other distributions to holders of the Company’s capital stock, make certain investments, engage in transactions with affiliates, create liens, open new deposit accounts, sell assets or pay subordinated debt. As of October 31, 2018, the Company had not drawn down from the facility and the Loan Agreement expired on October 31, 2018. In connection with the Loan Agreement, the Company agreed to issue a warrant to the lender for the purchase of up to 188,702 shares of the Company’s Series A Preferred Stock with an exercise price of $0.7949 per share. The warrant expires on June 22, 2027. The warrant was initially exercisable for the purchase of up to 28,305 shares of Series A Preferred Stock and could become exercisable for up to an additional 160,397 shares of Series A Preferred Stock based on the amounts drawn under the Loan Agreement. On the issuance date of the warrant, the Company recorded a deferred financing cost and a liability for the warrant to purchase preferred stock in the Company’s consolidated balance sheet equal to the issuance-date fair value of the warrant. Upon closing of the IPO, the carrying amount of the warrant to purchase preferred stock as of the date of IPO was transferred to the account of additional paid in capital (Note 3). On the date of issuance, the fair value of the warrant was determined to be $18. The Company recognized a loss of $162 and $17 in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2018 and 2017, respectively, related to the change in fair value of the warrant. On July 13, 2018, the lender of the Loan Agreement exercised its common stock warrants to purchase 6,850 shares of common stock on a net basis, resulting in the issuance of 6,091 shares of common stock.

7. Loan Agreement and Warrant to Purchase Preferred Stock

On June 23, 2017, the Company entered into the Loan Agreement with a lender, which provided for the issuance of term loans of up to $10,000, subject to the achievement of various development and corporate milestones. Any outstanding principal amounts under the Loan Agreement accrued interest at a floating per annum rate equal to the greater of 1% and the “prime rate,” as defined in the Loan Agreement, minus 3%.

The Loan Agreement contained customary indemnification obligations and customary events of default. In the event of default by the Company under the Loan Agreement, the lender would be entitled to exercise their remedies thereunder, including the right to accelerate the debt, upon which the Company may be required to repay all amounts then outstanding under the Loan Agreement or the lender may take possession of the collateral securing the Loan Agreement.

The Loan Agreement also includes certain restrictions on, among other things, the Company’s ability to incur additional indebtedness, change the name or location of its business, merge with or acquire other entities, pay dividends or make other distributions to holders of the Company’s capital stock, make certain investments, engage in transactions with affiliates, create liens, open new deposit accounts, sell assets or pay subordinated debt.

As of October 31, 2018, the Company had not drawn down from the facility and the Loan Agreement expired on October 31, 2018.

In connection with the Loan Agreement, the Company agreed to issue a warrant to the lender for the purchase of up to 188,702 shares of the Company’s Series A Preferred Stock with an exercise price of $0.7949 per share. The warrant expires on June 22, 2027. The warrant was initially exercisable for the purchase of up to 28,305 shares of Series A Preferred Stock and could become exercisable for up to an additional 160,397 shares of Series A Preferred Stock based on the amounts drawn under the Loan Agreement. On the issuance date of the warrant, the Company recorded a deferred financing cost and a liability for the warrant to purchase preferred stock in the Company’s consolidated balance sheet equal to the issuance-date fair value of the warrant. Upon closing of the IPO, the carrying amount of the warrant to purchase preferred stock as of the date of IPO was transferred to the account of additional paid in capital (Note 3).

On the date of issuance, the fair value of the warrant was determined to be $18. The Company recognized a loss of $162 and $17 in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2018 and 2017, respectively, related to the change in fair value of the warrant. On July 13, 2018, the lender of the Loan Agreement exercised its common stock warrants to purchase 6,850 shares of common stock on a net basis, resulting in the issuance of 6,091 shares of common stock.