| 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 |
| Revenue: | | | | | | | | |
| Total revenue | 0.3 | 0.1 | 0.1 | 0.1 | 0.4 | 1.7 | 3.1 | 3.3 |
| Total revenue growth | -34.3% | -91.8% | -96.0% | -98.1% | -87.1% | -5.2% | 343.9% | |
| Revenue from Contract with Customer, Product and Service [Extensible List] | | | | | | | | |
| Costs and expenses: | | | | | | | | |
| Research and development | 13.4 | 11.9 | 12.0 | 12.4 | 12.5 | 9.6 | 6.5 | 3.2 |
| Selling, general and administrative | 6.6 | 6.5 | 6.2 | 6.5 | 6.6 | 5.0 | 3.3 | 1.6 |
| Total costs and expenses | 20.0 | 18.3 | 18.3 | 18.9 | 19.2 | 18.5 | 17.9 | 14.2 |
| Loss from operations | -19.8 | -18.2 | -18.1 | -18.8 | -18.8 | -16.5 | -14.3 | -9.5 |
| Operating margin | -7850.0% | -12825.3% | -14686.2% | -30468.6% | -4907.0% | -951.4% | -461.5% | -292.1% |
| Interest income (expense) | 0.7 | 0.2 | | | | 0.0 | 0.0 | |
| Net loss | -19.0 | -17.9 | -18.1 | -18.8 | -18.8 | -16.8 | -14.8 | -11.0 |
| |
| Other comprehensive income, net of tax | | | | | | | | |
| Unrealized loss on marketable securities | -0.2 | | | | | | | |
| Comprehensive Loss | -5.9 | | | | -4.6 | | | |
| |
| Net loss per share - basic | ($1.62) | ($1.61) | ($1.63) | ($1.66) | ($1.66) | ($0.78) | ($0.86) | ($0.81) |
| Net loss per share - diluted | ($1.62) | ($1.61) | ($1.63) | ($1.66) | ($1.66) | ($0.56) | ($0.38) | ($0.18) |
| |
| Weighted average number of common share - basic | 20.8 | 20.5 | 20.0 | 18.2 | 18.2 | 20.2 | 16.4 | 13.9 |
| Weighted average number of common share - diluted | 20.8 | 20.5 | 20.0 | 18.2 | 18.2 | 17.1 | 10.8 | 6.3 |