| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | S-1/A |
| Net income | 0.0 | 0.0 | -28.9 | -31.9 | -29.5 | -18.7 | -13.9 |
| Depreciation and amortization [+] | | | 0.3 | 0.2 | 0.2 | 0.2 | 0.2 |
| Depreciation | | | 0.3 | 0.2 | 0.2 | 0.2 | 0.2 |
| Stock-based compensation | | | 0.7 | 0.4 | 0.2 | 0.3 | 0.1 |
| Change in working capital [+] | | | -1.1 | 0.5 | 1.9 | -0.9 | 1.7 |
| Accounts receivable | | | 0.7 | -0.3 | -0.5 | 0.0 | -0.1 |
| Other current assets | | | -0.2 | 0.7 | -0.4 | -0.3 | |
| Accounts payable | | | 0.1 | 0.7 | 0.4 | -0.6 | 0.4 |
| Accrued expenses | | | -1.7 | -0.7 | 2.4 | 0.0 | |
| Other | | | | | | | 1.3 |
| Other operating activities | -19.1 | -25.3 | 0.2 | 0.0 | 1.9 | -2.3 | -7.7 |
| Cash from operations | -19.1 | -25.3 | -28.6 | -30.7 | -25.3 | -21.4 | -19.7 |
| |
| Capital expenditures | 0.1 | 0.0 | -0.3 | -0.1 | -0.2 | -0.1 | -0.8 |
| Purchases of property and equipment | 0.1 | 0.0 | -0.3 | -0.1 | -0.2 | -0.1 | -0.8 |
| Sales of short-term investments, net [+] | | | | 14.2 | -14.0 | | |
| Purchases of short-term investments | | | | | -20.8 | | |
| Sales of short-term investments | | | | 14.2 | 6.8 | | |
| Other cash from investing | -0.2 | -0.1 | | | | | |
| Cash from investing | -0.1 | 0.0 | -0.3 | 14.1 | -14.2 | -0.1 | -0.8 |
| |
| Issuance of common stock, net | 3.6 | 32.8 | 28.5 | 13.8 | 37.1 | | |
| Option exercises | | | 0.0 | | 0.0 | 0.0 | |
| Financing costs | | | -0.1 | | | | |
| Other cash from financing | 13.4 | -9.5 | 8.3 | | 3.8 | 24.0 | 16.4 |
| Cash from financing | 17.0 | 23.3 | 36.8 | 13.8 | 41.0 | 24.0 | 16.4 |
| |
| Free cash flow | -19.0 | -25.3 | -28.9 | -30.8 | -25.5 | -21.5 | -20.5 |
| Per share (diluted) | ($0.45) | ($0.88) | ($1.54) | ($2.39) | ($4.88) | ($19.47) | ($38,594.10) |
| |
| Cash paid for interest | | | | | 0.3 | 0.0 | |