| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 |
| | 8-K | 10-K | 10-K | S-1 |
| Revenue from contract with customer, product and service, extensible enumeration | | | | |
| Service revenue | 0.3 | 0.3 | 0.4 | 0.0 |
| Service revenue growth | -9.4% | -9.6% | -19010516.7% | |
| Cost of revenue | | -0.1 | 0.4 | |
| Gross profit | 0.3 | 0.5 | 0.0 | |
| Gross margin | 91.3% | 140.9% | -0.8% | |
| |
| Operating expenses: | | | | |
| Research and development expenses | 41.7 | 51.3 | 22.7 | 9.8 |
| Selling, general and administrative expenses | 49.8 | 48.9 | 11.9 | |
| Total operating expenses | 91.5 | 209.2 | 70.8 | 15.1 |
| Loss from operations | -91.3 | -99.8 | -34.7 | -15.1 |
| Operating margin | -30526.8% | -30230.6% | -9497.5% | 788572812.5% |
| |
| Other income (expense): | | | | |
| Change in fair value of warrant liability | | 37.3 | -3.2 | |
| Realized (loss) gain on disposal of asset | | 0.0 | -0.5 | |
| Interest income | 0.5 | 0.0 | 0.0 | 0.0 |
| Interest expense | | -14.2 | -0.5 | -0.6 |
| Litigation settlement, net | | -7.0 | | |
| Other income | -0.2 | -5.0 | -0.9 | -0.1 |
| Total other income (expense) | -0.2 | 220.4 | -272.4 | -0.6 |
| Net loss | -95.4 | 120.7 | -307.0 | -15.8 |
| |
| Net loss per share, basic (in dollars per share) | ($1.17) | $1.85 | ($4.90) | ($0.16) |
| Net loss per share, fully diluted (in dollars per share) | ($1.17) | $1.70 | ($4.90) | ($0.16) |
| |
| Weighted average shares outstanding, basic (in shares) | 81.5 | 65.2 | 62.6 | 95.5 |
| Weighted average shares outstanding, fully diluted (in shares) | 81.5 | 70.9 | 62.6 | 95.5 |