Unaudited Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Preferred stock, par value (usd per share)	$ 0.0001	$ 0
Preferred stock, shares authorized (shares)	10,000,000	0
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value (usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (shares)	150,000,000	20,988,730
Common stock, shares issued (shares)	23,964,746	914,602
Common stock, shares outstanding (shares)	23,856,689	726,994
Series A redeemable convertible preferred stock
Redeemable convertible preferred stock, par value (usd per share)		$ 0.0001
Redeemable convertible preferred stock, shares authorized (shares)		45,000,000
Redeemable convertible preferred stock, shares issued (shares)		44,500,001
Redeemable convertible preferred stock, shares outstanding (shares)	0	44,500,001
Series B redeemable convertible preferred stock
Redeemable convertible preferred stock, par value (usd per share)		$ 0.0001
Redeemable convertible preferred stock, shares authorized (shares)		62,500,000
Redeemable convertible preferred stock, shares issued (shares)		62,500,000
Redeemable convertible preferred stock, shares outstanding (shares)	0	62,500,000

Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Per share amount of par value or stated value of stock classified as temporary equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable.

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