| In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 |
| | 10-K | 10-K | 10-K | 10-K/A | S-1/A |
| Cash flows used in operating activities | | | | | |
| Net loss | -42.9 | -50.0 | -55.2 | -23.2 | |
| |
| Adjustments to reconcile net loss to net cash used in operating activities: | | | | | |
| Depreciation of property and equipment | 0.1 | 0.1 | 0.0 | 0.0 | |
| Share-based compensation expense | 7.3 | 4.9 | 1.2 | 0.6 | |
| Changes in operating assets and liabilities: | | | | | |
| Other receivables | 0.1 | 0.0 | 0.1 | -0.3 | |
| Research and development tax credits receivable | 0.4 | -0.1 | -0.3 | 0.1 | |
| Prepaid expenses | 1.1 | -3.6 | -0.4 | -1.3 | |
| Accounts payable and accrued liabilities | 0.6 | -2.1 | 3.5 | 2.9 | |
| Net cash used in operating activities | -33.2 | -50.7 | -51.2 | -21.0 | |
| |
| Cash provided by (used in) investing activities | | | | | |
| Acquisition of property and equipment | | | -0.4 | 0.0 | |
| Acquisition of short-term investments | -15.0 | -90.0 | -35.0 | -3.0 | |
| Redemption of short-term investments | 85.0 | 20.0 | 35.0 | 19.0 | 0.0 |
| Net cash provided by (used in) investing activities | 70.0 | -70.0 | -0.4 | 16.0 | |
| |
| Cash provided by financing activities | | | | | |
| Proceeds from exercise of options | 0.1 | 0.3 | 0.0 | 0.5 | |
| Cash provided by financing activities | 5.1 | 73.2 | 85.4 | 80.1 | |