| In millions, except per share items | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | -33.9 | -18.4 | -26.3 | -61.3 | -23.5 | -13.3 | -4.7 | 4.5 |
| Depreciation and amortization | 50.7 | 50.7 | 49.7 | 45.7 | 42.8 | 26.6 | 10.9 | 6.0 |
| Stock-based compensation | 5.3 | 6.2 | 7.9 | 5.7 | 5.0 | 4.6 | 3.6 | 3.0 |
| Deferred taxes | -1.6 | -1.2 | -1.5 | -2.0 | 0.3 | 0.8 | -0.3 | 0.7 |
| Change in working capital [+] | 19.2 | -7.0 | -11.5 | -18.8 | 8.5 | 2.5 | -3.9 | -5.7 |
| Accounts receivable | 4.5 | -5.2 | -14.0 | -10.0 | -1.7 | 8.0 | -6.9 | -2.7 |
| Inventories | 10.0 | -5.6 | 8.3 | -16.9 | -2.0 | -8.0 | -5.3 | 0.7 |
| Other current assets | 3.8 | 2.4 | 4.0 | -10.5 | -4.6 | -0.4 | -0.2 | -0.4 |
| Deferred revenues | | | | | | -1.1 | 0.6 | -1.0 |
| Other | 0.8 | 1.3 | -9.8 | 18.7 | 16.7 | 4.0 | 7.9 | -2.2 |
| Other operating activities | 8.7 | -0.2 | -6.9 | 25.7 | -4.1 | 4.9 | -2.4 | 0.2 |
| Cash from operations | 48.4 | 30.1 | 11.5 | -5.0 | 28.9 | 26.1 | 3.2 | 8.8 |
| |
| Capital expenditures | -18.5 | -21.1 | -22.2 | -27.4 | -28.4 | -70.0 | -45.5 | -37.3 |
| Purchases of property and equipment | -18.5 | -21.1 | -22.2 | -27.4 | -28.4 | -70.0 | -45.5 | -37.3 |
| Acquisitions | | | | -67.9 | -3.5 | -141.6 | -28.9 | -7.1 |
| Sales of short-term investments, net [+] | | | | | | | | 27.8 |
| Purchases of short-term investments | | | | | | | | -51.4 |
| Sales of short-term investments | | | | | | | | 79.2 |
| Other cash from investing | -1.0 | | 0.7 | -0.7 | 0.8 | 123.0 | -121.1 | |
| Cash from investing | -19.5 | -21.1 | -21.5 | -95.9 | -31.1 | -88.6 | -195.6 | -16.6 |
| |
| Issuance of common stock, net | -2.5 | -9.4 | 28.0 | 15.0 | | | 114.8 | |
| Option exercises | 0.8 | 1.1 | 1.2 | 1.0 | 0.3 | 0.2 | 0.1 | 1.8 |
| Financing costs | -3.2 | | | -5.4 | | -0.9 | -3.7 | -1.4 |
| Other cash from financing | -43.5 | 2.2 | 2.4 | 90.9 | 0.3 | -2.5 | 97.7 | 42.2 |
| Cash from financing | -43.7 | -8.4 | 29.2 | 110.3 | 0.0 | -1.8 | 216.1 | 41.8 |
| |
| Free cash flow | 29.9 | 9.0 | -10.7 | -32.4 | 0.5 | -43.9 | -42.3 | -28.5 |
| Per share (diluted) | $0.38 | $0.11 | ($0.14) | ($0.44) | $0.01 | ($0.62) | ($0.75) | ($0.59) |
| |
| Cash paid for interest | 23.9 | 20.0 | 20.0 | 12.9 | 8.8 | 9.0 | 3.3 | 4.3 |
| Cash paid for income taxes | 5.8 | 4.8 | 5.5 | 0.8 | -0.1 | 0.7 | 0.7 | 1.4 |