| In millions, except per share items | Mar-31-22 | Dec-31-21 | Sep-30-21 | Mar-31-21 | Dec-31-20 | Sep-30-20 | Jun-30-20 | Jun-05-20 |
| | 10-Q | 10-K | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 8-K |
| Service revenue | | | | 0.3 | 0.2 | | | |
| Service revenue growth | | | | | | -25.7% | | |
| Operating expenses: | | | | | | | | |
| Cost of service revenue | | | | 0.2 | | | | |
| Research and development | | | | 21.4 | 21.6 | 21.9 | 22.6 | |
| General and administrative | | | | 10.9 | 11.2 | 11.7 | 12.0 | |
| Total operating expenses | | | | 25.0 | 25.3 | 17.1 | | |
| Loss from operations | | | | -32.2 | -32.8 | -33.6 | -34.6 | |
| Operating margin | | | | -12484.5% | | -680.6% | | |
| |
| Other income (expense): | | | | | | | | |
| Interest income | | | | 0.0 | 0.0 | 0.0 | 0.1 | |
| Interest expense | | | | -0.6 | -0.7 | -0.7 | -0.8 | |
| Other income (expense), net | | | | 0.0 | 0.1 | 0.1 | 0.0 | |
| Loss before provision for income taxes | | | | -32.8 | -33.4 | -26.3 | -35.4 | |
| Net loss | | | | -32.8 | -33.4 | -34.2 | -35.4 | |
| |
| Net loss per common share - basic (in USD per share) | | | | ($3.02) | ($0.53) | ($0.94) | ($1.38) | |
| Net loss per common share - diluted (in USD per share) | | | | ($3.02) | ($0.53) | ($0.94) | ($1.38) | |
| |
| Weighted-average common shares used in computing net loss per common share – basic | | | | 50.9 | 59.2 | 46.4 | 31.4 | |
| Weighted-average common shares used in computing net loss per common share – diluted | | | | 50.9 | 59.2 | 46.4 | 31.4 | |
| |
| Revenue from Contract with Customer, Product and Service [Extensible List] | | | | | | | | |
| Cost, Product and Service [Extensible List] | | | | | | | | |