Redeemable Convertible Preferred Stock	9 Months Ended
Redeemable Convertible Preferred Stock	Sep. 30, 2019
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred Stock On January 2, 2019, the Company amended and restated its restated certificate of incorporation to, among other things, increase its authorized shares of convertible preferred stock from 750,300,000 to 955,500,000 shares, of which 205,200,000 shares are designated as Series G convertible preferred stock and set forth the rights, preferences and privileges of the Series G convertible preferred stock. On July 11, 2019, the Company amended and restated its restated certificate of incorporation to among other things, increase its authorized shares of convertible preferred stock from 955,500,000 to 1,038,667,059 shares, of which 479,967,595 shares are designated as Series H redeemable convertible preferred stock and set forth the rights, preferences and privileges of the Series H redeemable convertible preferred stock. Upon completion of the Company's IPO in September 2019, an aggregate of 7,816,643 shares of common stock, excluding warrant conversions, were issued to the holders of the Company's Series A-3, Series B-3, Series C, Series D, Series E, Series F and Series H redeemable convertible preferred stockholders upon the automatic conversion of all shares of redeemable convertible preferred stock to common stock. As a result, no shares of redeemable convertible preferred stock remain outstanding at September 30, 2019. Series F Financing In December 2017, the Company's Board of Directors authorized a third tranche closing of the issuance to existing preferred stockholders in connection with the Company's Series F financing, which was completed between December 2017 and January 2018. In December 2017, a group of existing investors of the Company purchased 54,246,756 shares of Series F redeemable convertible preferred stock at a per share price of $0.078 for aggregate gross proceeds of approximately $4.2 million. In early January 2018, a group of existing stockholders of the Company purchased an additional 34,914,327 shares of Series F redeemable convertible preferred stock at a per share price of $0.078 for aggregate gross proceeds of approximately $2.7 million. The Company concluded that the third tranche closing of the Series F preferred stock purchase agreement contained a single freestanding financial instrument, shares of Series F redeemable convertible preferred stock, and the Company determined there were no embedded features requiring bifurcation in the shares of Series F redeemable convertible preferred stock issued in the third tranche closing. The Company accounted for the difference between the estimated fair value and the $0.078 per share purchase price of shares of Series F redeemable convertible preferred stock issued in the third tranche closing as a deemed dividend since all investors in the third closing are existing preferred stockholders of the Company, and the Company did not identify any elements to the transaction which it believes were compensatory in nature. As a result, the Company recognized a deemed dividend in the amount of $1.2 million in the first quarter of 2018, that was recorded as additional paid-in capital (in the absence of retained earnings) in the accompanying condensed statement of redeemable convertible preferred stock and stockholders’ deficit. Series G Financing In January 2019, the Company entered into an agreement with new and certain existing preferred stockholders to issue shares of Series G redeemable convertible preferred stock in multiple separate closings at per share price of $0.078 in each closing. Shares of Series G redeemable convertible preferred stock were issuable under the Series G preferred stock purchase agreement until the earlier of March 31, 2019 or the issuance of all authorized shares of Series G redeemable convertible preferred stock, as specified in the Company's amended and restated certificate of incorporation. In January 2019 and March 2019, the Company sold 88,030,905 and 9,615,384 shares, respectively, of Series G redeemable convertible preferred stock for aggregate gross proceeds of approximately $7.6 million to new and existing investors, of which $3.75 million of gross proceeds were received as of December 31, 2018 and are included in the accompanying December 31, 2018 balance sheet. In May 2019, the Company sold an additional 51,282,048 shares of Series G redeemable convertible preferred stock for aggregate gross proceeds of approximately $4.0 million to existing investors. In addition, in May 2019, the Series G preferred stock purchase agreement was amended to include the right of the Company to require certain holders of Series G redeemable convertible preferred stock to purchase an additional 32,051,280 shares of Series G redeemable convertible preferred stock at $0.078 per share, for total aggregate proceeds of $2.5 million, at any time after July 31, 2019 and prior to May 31, 2020. This right terminated in connection with the issuance of the Series H redeemable convertible stock in July 2019. The Company concluded that the closings of the Series G preferred stock purchase agreement in January and March 2019, contained a single freestanding financial instrument, shares of Series G redeemable convertible preferred stock, and the Company determined there were no embedded features requiring bifurcation in the shares of Series G redeemable convertible preferred stock issued. The Company concluded the closing in May 2019 contained two freestanding financial instruments, shares of Series G redeemable convertible preferred stock and the Company call right, and the Company concluded there were no embedded features requiring bifurcation in the shares of Series G redeemable convertible preferred stock issued. The Company call right was deemed to have nominal value since it was with insiders with knowledge of the imminent closing of Series H redeemable convertible stock. Series H Financing In July 2019, the Company entered into an agreement with a new investor to issue shares of Series H redeemable convertible preferred stock at a per share price of $0.04712. Pursuant to the terms of the agreement, the new investor purchased 233,446,519 shares of Series H redeemable convertible preferred stock for gross proceeds of approximately $11.0 million. In connection with the Series H financing, the Company converted all of the 148,928,337 outstanding shares of the Company's Series G redeemable convertible preferred stock into 246,521,076 shares of Series H redeemable convertible preferred stock on a dollar-for-dollar basis. The Company concluded that the closing of the Series H preferred stock purchase agreement contained a single freestanding financial instrument, shares of Series H redeemable convertible preferred stock, and the Company determined there were no embedded features requiring bifurcation in the shares of Series H redeemable convertible preferred stock issued at closing. The Company accounted for the difference between the effective conversion price of $0.04712 and the fair value of the underlying common stock at the commitment date as a beneficial conversion feature, which was immediately accreted as a deemed dividend. As a result, the Company recognized a beneficial conversion feature in the amount of $6.7 million in the third quarter of 2019, that was recorded as additional paid-in capital (in the absence of retained earnings) in the accompanying condensed statement of redeemable convertible preferred stock and stockholders’ equity (deficit). Additionally, the Company concluded that the conversion of shares of Series G into shares of Series H redeemable convertible preferred stock in connection with the issuance of Series H redeemable convertible preferred stock represented an extinguishment of the Series G shares. As a result, the Company recognized a deemed dividend for the extinguishment charge in the amount of $6.9 million in the third quarter of 2019, that was recorded as additional paid-in capital (in the absence of retained earnings) in the accompanying condensed statement of redeemable convertible preferred stock and stockholders' equity (deficit).