| 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 | 0.1 | 0.1 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.3 |
| Total revenue growth | 1676.7% | 40.2% | 3169.9% | -97.8% | -99.5% | -96.7% | -98.9% | 771.7% |
| Revenue from Contract with Customer, Product and Service [Extensible List] | | | | | | | | |
| Costs and expenses: | | | | | | | | |
| Research and development | 4.5 | 2.9 | 3.1 | 3.0 | 3.0 | 3.0 | 3.4 | 3.2 |
| Selling, general and administrative | 1.8 | 1.9 | 1.3 | 1.5 | 1.7 | 1.7 | 1.7 | 1.6 |
| Total costs and expenses | 6.3 | 4.8 | 4.4 | 4.5 | 4.6 | 4.7 | 5.0 | 4.8 |
| Loss from operations | -6.2 | -4.7 | -4.3 | -4.5 | -4.6 | -4.6 | -5.0 | -4.5 |
| Operating margin | -5328.1% | -7307.6% | -6819.6% | -61899.6% | -70817.1% | -10081.5% | -259334.4% | -1361.2% |
| Interest income (expense) | 0.4 | 0.2 | | | | 0.0 | 0.0 | |
| Net loss | -5.8 | -4.5 | -4.3 | -4.5 | -4.6 | -4.6 | -5.0 | -4.5 |
| |
| Other comprehensive income, net of tax | | | | | | | | |
| Unrealized loss on marketable securities | -0.2 | | | | | | | |
| Comprehensive Loss | -5.9 | | | | -4.6 | | | |
| |
| Net loss per share - basic | ($1.11) | ($0.16) | ($0.17) | ($0.18) | ($1.10) | ($0.18) | ($0.20) | ($0.18) |
| Net loss per share - diluted | ($1.11) | ($0.16) | ($0.17) | ($0.18) | ($1.10) | ($0.18) | ($0.20) | ($0.18) |
| |
| Weighted average number of common share - basic | 5.2 | 27.5 | 25.2 | 25.2 | 4.2 | 25.2 | 18.2 | 25.1 |
| Weighted average number of common share - diluted | 5.2 | 27.5 | 25.2 | 25.2 | 4.2 | 25.2 | 18.2 | 25.1 |