In millions, except per share items | Jun-30-23 | Mar-31-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 |
| 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
Assets [Abstract] | | | | | | | | |
Current assets: | | | | | | | | |
Cash and cash equivalents | 17.6 | 22.9 | 31.2 | 42.8 | 51.6 | 45.8 | 51.8 | 59.7 |
Insurance recovery of legal settlement | | 0.5 | 0.5 | 15.2 | 15.0 | 15.0 | 15.0 | |
Prepaid expenses and other current assets | 1.3 | 1.7 | 1.5 | 3.2 | 2.5 | 2.6 | 2.7 | 3.5 |
Total current assets | 18.5 | 24.7 | 33.0 | 60.3 | 68.3 | 62.7 | 69.0 | 62.6 |
Property and equipment-net | 1.0 | 1.0 | 1.1 | 0.9 | 1.0 | 1.0 | 1.1 | 1.1 |
Operating lease right-of-use assets | 10.8 | 11.2 | 11.7 | 1.3 | 1.6 | 2.7 | 3.1 | |
Other noncurrent assets | 0.4 | 0.4 | 0.4 | 0.7 | 0.5 | 0.5 | 0.1 | 0.1 |
Total assets | 30.7 | 37.3 | 46.1 | 63.2 | 71.4 | 67.0 | 73.2 | 67.1 |
|
Liabilities and Equity [Abstract] | | | | | | | | |
Liabilities [Abstract] | | | | | | | | |
Current liabilities: | | | | | | | | |
Accounts payable | 0.9 | 1.2 | 1.1 | 0.9 | 1.4 | 0.7 | 1.0 | 2.4 |
Accrued legal settlement | | 0.5 | 0.5 | 15.2 | 15.0 | 15.0 | 15.0 | |
Accrued expenses | 2.5 | 2.5 | 3.0 | 16.1 | 15.6 | 15.3 | 15.9 | 1.7 |
Current loan payable | 3.0 | 1.5 | | | | | | |
Current operating lease liabilities | 1.4 | 1.3 | 1.4 | 0.9 | 1.1 | 1.5 | 1.4 | |
Accrued compensation | 0.8 | 0.5 | 1.2 | 0.9 | 0.6 | 0.3 | 0.9 | 0.7 |
Interest payable | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 |
Total current liabilities | 8.6 | 7.5 | 7.3 | 24.1 | 22.4 | 20.8 | 20.0 | 6.2 |
Loan payable (net of discount and issuance costs of $263 and $454, respectively) | 7.5 | 8.9 | 10.4 | 11.8 | 13.3 | 15.1 | 15.1 | 15.0 |
Operating lease liabilities, less current portion | 9.6 | 9.9 | 10.3 | 0.5 | 0.7 | | 2.0 | |
Total liabilities | 25.7 | 26.4 | 28.0 | 36.4 | 36.4 | 37.6 | 37.1 | 23.6 |
|
Commitments and contingencies (Note 5) | | | | | | | | |
Stockholders' equity: | | | | | | | | |
Common stock | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Additional paid-in capital | 156.0 | 154.4 | 153.9 | 153.4 | 152.6 | 137.9 | 136.2 | 135.9 |
Accumulated deficit | -151.0 | -143.4 | -135.8 | -126.7 | -117.7 | -108.6 | -100.1 | -92.3 |
Total stockholders’ equity | 5.0 | 11.0 | 18.1 | 26.8 | 34.9 | 29.4 | 36.1 | 43.5 |
Total liabilities and stockholders’ equity | 30.7 | 37.3 | 46.1 | 63.2 | 71.4 | 67.0 | 73.2 | 67.1 |