Unaudited Condensed Statements of Stockholders' Equity (Deficit) - Parenthetical - $ / shares |
Sep. 30, 2019 |
Dec. 31, 2018 |
Mar. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|---|---|
| Statement of Stockholders' Equity [Abstract] | ||||
| Common stock, par or stated value per share (in usd per share) | $ 0.0001 | $ 0.0001 | $ 0.0001 | $ 0.001 |