| 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 |
| Operating expenses | | | | | | | | |
| Research and development | 56.6 | 51.4 | 49.8 | 39.6 | 30.3 | 40.2 | 35.1 | 29.6 |
| General and administrative | 32.2 | 33.2 | 35.1 | 35.6 | 32.7 | 28.9 | 22.9 | 17.7 |
| Total operating expenses | 88.8 | 84.6 | 84.9 | 75.3 | 63.0 | 69.0 | 58.0 | 47.3 |
| Loss from operations | -88.8 | -84.6 | -84.9 | -75.3 | -63.0 | -69.0 | -58.0 | -47.3 |
| Other income (expense), net | 5.5 | 4.8 | 3.5 | 1.3 | 0.1 | -0.4 | -0.4 | -0.4 |
| Net loss | -83.3 | -79.8 | -81.4 | -74.0 | -62.8 | -69.3 | -58.4 | -47.6 |
| |
| Other comprehensive income (loss) | | | | | | | | |
| Foreign currency translation adjustment | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | | |
| Unrealized gain (loss) on marketable securities | 0.0 | | | | | | | |
| Comprehensive loss | -83.3 | -79.8 | -81.3 | -74.0 | -62.8 | -69.3 | -58.4 | -47.6 |
| |
| Shares used in calculating net loss per common share - basic (in shares) | 223.8 | 218.1 | 213.2 | 208.3 | 203.8 | 198.8 | 193.9 | 173.2 |
| Shares used in calculating net loss per common share - diluted (in shares) | 223.8 | 218.1 | 213.2 | 208.3 | 203.8 | 198.8 | 193.9 | 173.2 |
| |
| Net loss per share of common stock - basic (in USD per share) | ($0.37) | ($0.36) | ($0.38) | ($0.35) | ($0.30) | ($0.34) | ($0.29) | ($0.20) |
| Net loss per share of common stock - diluted (in USD per share) | ($0.37) | ($0.36) | ($0.38) | ($0.35) | ($0.30) | ($0.34) | ($0.29) | ($0.20) |