| 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 | -0.1 | -2.5 | -3.8 | 5.5 | 4.5 | -4.9 | 5.3 | 5.6 |
| Depreciation and amortization | 5.5 | 4.6 | 3.3 | 2.9 | 2.1 | 2.0 | 1.8 | 2.2 |
| Asset impairment charges | | | | | | 0.8 | | |
| Stock-based compensation | 2.2 | 2.4 | | | 0.8 | 0.7 | 0.6 | 0.5 |
| Change in working capital [+] | -0.8 | -1.4 | -0.2 | -0.4 | 1.3 | 0.7 | -3.9 | -2.3 |
| Accounts receivable | 2.0 | 0.5 | | | -2.0 | 1.5 | -0.8 | -2.2 |
| Inventories | -4.9 | -1.2 | | | -2.6 | 1.1 | -4.3 | -0.7 |
| Accounts payable | 0.6 | -2.1 | | | 3.8 | -1.4 | 1.6 | 0.6 |
| Accrued expenses | 2.3 | 1.7 | | | 2.1 | -0.5 | -0.1 | -0.3 |
| Other | -0.8 | -0.3 | -0.2 | -0.4 | 0.1 | 0.0 | -0.2 | 0.3 |
| Other operating activities | -6.4 | 2.6 | 2.2 | -6.6 | -3.4 | 0.4 | -3.1 | -2.9 |
| Cash from operations | 0.4 | 5.6 | 1.5 | 1.5 | 5.4 | -0.4 | 0.7 | 3.2 |
| |
| Capital expenditures [+] | -2.5 | -3.6 | 4.6 | 5.5 | -2.3 | -1.8 | -4.0 | -1.5 |
| Purchases of property and equipment | -2.5 | -3.6 | 4.6 | 5.5 | -2.3 | -1.8 | -4.0 | -1.5 |
| Sales of property and equipment | | | | | 0.0 | | | 0.1 |
| Purchases of intangible assets | -0.2 | | | | | | | |
| Acquisitions | | -7.1 | | | -0.7 | -0.5 | | |
| Purchases of short-term investments, net | 0.7 | 7.3 | 93.4 | 38.1 | | | | |
| Purchases of short-term investments | -24.8 | -19.9 | 43.8 | 38.1 | | | | |
| Sales of short-term investments | 25.4 | 27.2 | 49.6 | | | | | |
| Other cash from investing | -0.2 | | -98.2 | -88.6 | -1.8 | | -0.2 | 0.5 |
| Cash from investing | -2.2 | -3.5 | -0.2 | -45.0 | -4.7 | -2.3 | -4.2 | -1.0 |
| |
| Issuance of common stock, net | | | | 63.1 | | 3.7 | | |
| Option exercises | 0.5 | 0.2 | 0.3 | 0.7 | 0.3 | 0.1 | 0.3 | 0.2 |
| Financing costs | | | | 0.1 | -0.1 | -0.1 | | |
| Other cash from financing | -0.7 | -1.8 | 0.2 | -10.2 | 0.1 | -0.2 | 4.1 | -1.8 |
| Cash from financing | -1.2 | -2.0 | -0.1 | 52.0 | 0.0 | 3.5 | 3.7 | -1.9 |
| |
| Free cash flow | -2.1 | 2.0 | 6.1 | 7.0 | 3.1 | -2.2 | -3.3 | 1.6 |
| Per share (diluted) | ($0.23) | $0.22 | $0.70 | $0.81 | $0.42 | ($0.33) | ($0.53) | $0.27 |