| 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 | -109.7 | -88.4 | -46.2 | -61.1 | -122.1 | -210.1 | -54.9 | -47.0 |
| Depreciation and amortization | 21.9 | 22.2 | 24.5 | 31.2 | 34.5 | 26.8 | 8.2 | 2.9 |
| Asset impairment charges | | | 7.6 | 1.3 | | 9.5 | | |
| Stock-based compensation | 6.1 | 9.7 | 8.5 | 9.0 | 16.3 | 11.3 | 3.0 | 1.1 |
| Change in working capital [+] | -15.1 | -0.8 | 2.9 | 11.4 | 1.8 | -12.5 | 18.8 | 14.0 |
| Accounts receivable | -0.3 | -0.1 | 0.1 | 0.3 | 1.3 | 0.6 | -0.4 | -0.3 |
| Inventories | 0.2 | -6.8 | 8.1 | 8.6 | 9.8 | 0.5 | -25.7 | -16.2 |
| Other current assets | -6.0 | 11.2 | -14.4 | 3.0 | -2.7 | -0.8 | -3.6 | -3.4 |
| Accounts payable | -9.2 | 4.3 | -0.5 | 1.7 | -6.6 | -4.8 | 3.7 | 18.9 |
| Deferred revenues | | | | | | | 18.0 | 4.0 |
| Other | 0.3 | -9.4 | 9.5 | -2.2 | 0.0 | -7.9 | 26.8 | 11.0 |
| Other operating activities | 5.3 | 8.4 | -2.6 | -8.2 | -7.4 | 22.6 | 1.3 | 2.5 |
| Cash from operations | -91.6 | -49.0 | -5.4 | -16.5 | -76.9 | -152.4 | -23.5 | -26.4 |
| |
| Capital expenditures [+] | -6.6 | -5.1 | -6.0 | -5.2 | -15.0 | -124.2 | -62.8 | -11.9 |
| Purchases of property and equipment | -6.6 | -5.1 | -6.0 | -5.2 | -15.0 | -124.2 | -62.8 | -11.9 |
| Sales of property and equipment | 0.2 | 1.4 | 0.2 | 0.7 | 1.0 | 0.1 | | 0.0 |
| Acquisitions | | | | | -0.3 | -1.2 | | |
| Sales of short-term investments | | | | | | | | 6.0 |
| Sales of short-term investments | | | | | | | | 6.0 |
| Other cash from investing | | | | | | | -3.6 | |
| Cash from investing | -6.4 | -3.7 | -5.8 | -4.5 | -14.3 | -125.3 | -66.5 | -5.9 |
| |
| Issuance of common stock, net | 82.2 | 99.6 | 68.1 | | | 283.5 | | |
| Option exercises | | | 0.5 | 0.1 | 0.2 | 1.0 | 0.4 | 0.1 |
| Financing costs | -2.3 | -5.6 | -2.3 | -0.8 | -0.9 | | | |
| Other cash from financing | -35.4 | -14.7 | -59.4 | -30.7 | -43.1 | 140.7 | 45.0 | 137.1 |
| Cash from financing | 49.1 | 90.4 | 10.5 | -29.9 | -42.4 | 423.2 | 44.6 | 137.0 |
| |
| Free cash flow | -98.2 | -54.0 | -11.4 | -21.7 | -91.9 | -276.7 | -86.4 | -38.3 |
| Per share (diluted) | ($2.70) | ($2.42) | ($0.75) | ($1.66) | ($7.16) | ($32.41) | ($1.32) | ($0.75) |
| |
| Cash paid for interest | 3.5 | 7.0 | 6.3 | 10.0 | 8.3 | 4.7 | 0.1 | 0.0 |
| Cash paid for income taxes | 0.0 | 0.0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.4 | |