| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | -113.3 | -65.2 | -41.3 | -25.1 | -19.9 | -23.6 |
| Depreciation and amortization | 8.4 | 6.0 | 5.8 | 4.7 | 3.1 | 1.2 |
| Stock-based compensation | | | | 4.9 | 1.3 | 0.8 |
| Change in working capital [+] | -1.5 | 3.4 | 3.5 | 1.9 | -0.7 | 2.2 |
| Accounts receivable | | | | 1.1 | -2.5 | -1.2 |
| Other current assets | | | | -2.6 | -1.3 | 0.2 |
| Accounts payable | | | | 1.4 | 2.2 | 2.6 |
| Accrued expenses | -1.5 | 3.4 | 3.5 | 2.0 | 1.0 | 0.7 |
| Other | | | | | -0.1 | -0.1 |
| Other operating activities | 36.1 | -15.0 | -10.7 | -4.5 | 21.8 | 19.7 |
| Cash from operations | -70.2 | -70.8 | -42.7 | -18.1 | 5.6 | 0.3 |
| |
| Capital expenditures | 49.9 | 11.1 | 3.2 | -8.4 | -7.9 | -5.2 |
| Purchases of property and equipment | 49.9 | 11.1 | 3.2 | -8.4 | -7.9 | -5.2 |
| Purchases of short-term investments, net | 345.4 | 485.3 | 261.7 | -73.2 | | |
| Purchases of short-term investments | 121.5 | 267.1 | 161.8 | -78.9 | | |
| Sales of short-term investments | 223.9 | 218.1 | 99.9 | 5.7 | | |
| Other cash from investing | -342.8 | -556.4 | -330.0 | | | |
| Cash from investing | 52.5 | -60.1 | -65.1 | -81.6 | -7.9 | -5.2 |
| |
| Issuance of common stock, net | | 162.3 | 117.5 | 144.0 | | |
| Option exercises | 2.5 | 4.5 | 4.2 | 1.4 | 0.1 | 0.1 |
| Financing costs | | | | -0.5 | | -0.1 |
| Other cash from financing | 3.8 | 11.9 | 8.0 | -8.2 | -0.5 | 16.4 |
| Cash from financing | 1.4 | 169.7 | 121.3 | 134.9 | -0.6 | 16.4 |
| |
| Free cash flow | -20.3 | -59.7 | -39.4 | -26.5 | -2.3 | -4.9 |
| Per share (diluted) | ($0.44) | ($1.36) | ($1.15) | ($1.47) | ($0.74) | ($1.61) |
| |
| Cash paid for interest | | | | 1.3 | 0.7 | 0.3 |
| Cash paid for income taxes | 0.0 | 0.0 | 0.0 | 0.0 | | |