| 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 | Dec-31-15 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | -42.8 | -54.4 | -59.9 | -71.2 | -57.6 | -60.6 | -62.9 | -55.9 |
| Depreciation and amortization [+] | 2.5 | 2.5 | 2.2 | 2.2 | 1.4 | 1.8 | 1.8 | 1.7 |
| Depreciation | | | | | | | | 1.5 |
| Amortization | | | | | | | | 0.2 |
| Asset impairment charges | | | | | | | 0.2 | |
| Stock-based compensation | | | | | 10.4 | 9.4 | 8.1 | 6.7 |
| Deferred taxes | | | | | | | 0.0 | 0.0 |
| Change in working capital [+] | 6.4 | 10.5 | 6.7 | 13.1 | 20.1 | -64.6 | 4.3 | 11.8 |
| Accounts receivable | | | | | 3.7 | -5.5 | -1.1 | -0.3 |
| Inventories | | | | | 0.8 | -2.1 | -1.8 | 4.0 |
| Accounts payable | | | | | 5.7 | 2.5 | 3.3 | -3.9 |
| Deferred revenues | | | | | | | | 0.2 |
| Other | 6.4 | 10.5 | 6.7 | 13.1 | 9.9 | -59.5 | 3.9 | 11.8 |
| Other operating activities | 8.3 | 7.5 | 9.1 | -9.5 | -5.6 | 61.8 | -5.0 | -15.5 |
| Cash from operations | -25.6 | -33.9 | -41.8 | -65.5 | -31.2 | -52.2 | -53.5 | -51.1 |
| |
| Capital expenditures | 2.0 | 0.9 | 1.6 | 8.9 | -1.1 | -0.4 | -0.6 | -0.7 |
| Purchases of property and equipment | 2.0 | 0.9 | 1.6 | 8.9 | -1.1 | -0.4 | -0.6 | -0.7 |
| Sales of short-term investments | 40.1 | 65.7 | 50.9 | 81.0 | 38.0 | 69.6 | 63.5 | 92.6 |
| Sales of short-term investments | 40.1 | 65.7 | 50.9 | 81.0 | 38.0 | 69.6 | 63.5 | 92.6 |
| Other cash from investing | -33.6 | -53.9 | -102.0 | -61.8 | -80.7 | -68.8 | -82.8 | -90.4 |
| Cash from investing | 8.5 | 12.7 | -49.6 | 28.2 | -43.8 | 0.4 | -19.9 | 1.5 |
| |
| Issuance of common stock, net | -0.1 | 2.7 | 76.5 | 26.9 | 85.0 | 30.2 | 25.2 | 88.1 |
| Option exercises | 4.1 | 9.4 | 11.8 | 3.2 | 7.8 | 2.4 | | |
| Other cash from financing | 8.4 | 40.9 | 27.0 | 19.8 | 15.6 | 15.2 | -0.6 | 9.9 |
| Cash from financing | 4.2 | 34.3 | 91.8 | 43.5 | 92.8 | 43.0 | 24.6 | 98.0 |
| |
| Free cash flow | -23.6 | -33.0 | -40.2 | -56.6 | -32.4 | -52.6 | -54.1 | -51.9 |
| Per share (diluted) | ($0.13) | ($0.19) | ($0.25) | ($0.40) | ($0.25) | ($0.49) | ($0.53) | ($0.54) |
| |
| Cash paid for interest | 5.1 | 4.2 | 3.3 | 3.1 | 2.7 | 2.0 | 1.4 | 1.1 |