| In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | -17.1 | -20.9 | -19.3 | -16.5 | -19.0 | -26.0 | -22.7 | -17.6 |
| Depreciation and amortization | 0.7 | 1.3 | 1.3 | 1.5 | 1.2 | 1.5 | 0.7 | 0.5 |
| Asset impairment charges | 0.2 | 0.1 | 0.2 | 0.1 | 0.4 | 0.7 | 0.2 | 0.1 |
| Stock-based compensation | 1.3 | 1.6 | 1.2 | 1.9 | 1.4 | 0.9 | 0.4 | 0.2 |
| Change in working capital [+] | 4.8 | 6.6 | 4.6 | 4.2 | -10.0 | 9.2 | 7.9 | 4.1 |
| Accounts receivable | -0.8 | 1.6 | 1.8 | 1.3 | -5.0 | -0.7 | 0.0 | -0.3 |
| Inventories | -1.4 | -0.3 | -0.1 | -0.2 | 0.1 | 0.0 | -0.7 | -0.7 |
| Other current assets | 0.6 | 0.3 | -0.2 | -0.1 | 0.0 | 0.0 | -0.3 | 0.1 |
| Accounts payable | 0.5 | 0.0 | -0.2 | -0.2 | 1.2 | 0.0 | -0.3 | 0.2 |
| Accrued expenses | 0.6 | -0.4 | -1.4 | -0.4 | 2.1 | 0.1 | 0.5 | 0.3 |
| Deferred revenues | | | | | | 0.3 | 0.0 | -0.1 |
| Other | 5.3 | 5.4 | 4.6 | 3.7 | -8.4 | 9.5 | 8.7 | 4.8 |
| Other operating activities | -6.4 | -5.0 | -4.5 | -4.3 | 9.4 | -8.5 | -5.7 | -0.2 |
| Cash from operations | -16.5 | -16.3 | -16.7 | -13.2 | -16.6 | -22.2 | -19.2 | -13.0 |
| |
| Capital expenditures | -0.6 | -0.5 | -1.1 | -0.9 | -1.0 | -1.9 | -1.3 | -0.9 |
| Purchases of property and equipment | -0.6 | -0.5 | -1.1 | -0.9 | -1.0 | -1.9 | -1.3 | -0.9 |
| Purchases of short-term investments, net | -6.0 | 19.2 | -2.4 | -22.3 | 4.3 | 26.4 | -30.8 | |
| Purchases of short-term investments | -18.6 | -12.5 | -34.6 | -54.0 | | -3.4 | -38.3 | |
| Sales of short-term investments | 12.6 | 31.7 | 32.2 | 31.7 | 4.3 | 29.8 | 7.5 | |
| Cash from investing | -6.7 | 18.7 | -3.5 | -23.2 | 3.3 | 24.4 | -32.2 | -0.9 |
| |
| Issuance of common stock, net | | 0.6 | | 37.7 | -0.2 | 2.0 | 47.7 | |
| Option exercises | 0.1 | 0.0 | 0.1 | 0.3 | 0.4 | 0.2 | 0.0 | 0.0 |
| Financing costs | | -0.1 | | | 0.0 | | -0.1 | |
| Other cash from financing | 10.5 | 8.4 | 19.5 | 0.7 | 16.2 | 0.2 | 3.4 | 15.7 |
| Cash from financing | 10.4 | 9.0 | 19.4 | 38.1 | 15.8 | 2.0 | 51.1 | 15.7 |
| |
| Free cash flow | -17.2 | -16.7 | -17.8 | -14.1 | -17.6 | -24.2 | -20.6 | -13.9 |
| Per share (diluted) | ($2.47) | ($3.62) | ($7.01) | ($0.51) | ($1.66) | ($3.40) | ($4.55) | ($137.64) |
| |
| Cash paid for interest | 0.6 | 0.9 | 0.7 | 0.6 | 0.7 | 1.1 | 0.9 | 0.4 |
| Cash paid for income taxes | 0.0 | 0.0 | 0.0 | | | | | |