Stockholders' Equity (Common Stock are Reserved for Future Issuance) (Details) - shares shares in Thousands |
Jun. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Equity [Abstract] | ||
| Warrants outstanding (in shares) | 1,812 | 963 |
| Series A Convertible Preferred (in shares) | 1,345 | |
| Stock options outstanding (in shares) | 473 | 10 |
| Options reserved for future issuance under the Company's 2017 Incentive Plan (in shares) | 343 | |
| Shares reserved for future issuance under the Employee Stock Purchase Plan (in shares) | 115 | |
| Restricted stock units (in shares) | 13 | |
| Total reserved for future issuance (in shares) | 4,101 |