| 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 | 8-K |
| Net income | 70.1 | -186.0 | -237.2 | -32.4 | -63.1 | -84.5 | -12.7 | 25.4 |
| Depreciation and amortization | 37.6 | 41.5 | 45.9 | 49.1 | 64.9 | 52.1 | 48.7 | |
| Asset impairment charges | | 64.6 | 191.8 | | | 75.2 | | |
| Stock-based compensation | 0.2 | 7.0 | 6.3 | 10.1 | 12.3 | 7.9 | 7.3 | |
| Deferred taxes | 0.7 | 4.5 | -4.0 | 3.8 | -31.7 | -66.2 | -4.2 | |
| Change in working capital [+] | -5.0 | 18.8 | 72.6 | 27.2 | 21.9 | -3.7 | 31.2 | |
| Accounts receivable | -33.5 | 0.7 | 46.1 | 27.2 | 15.4 | -39.8 | 16.5 | |
| Inventories | -1.7 | 0.5 | 2.7 | 9.6 | 0.0 | 0.6 | 2.1 | |
| Other current assets | -3.2 | 4.2 | -0.2 | 0.5 | 6.9 | 6.6 | -0.2 | |
| Accounts payable | -13.3 | 1.2 | 3.8 | -5.4 | -9.0 | 6.4 | 8.4 | |
| Accrued expenses | 15.2 | 11.6 | -12.8 | -8.4 | 9.2 | 14.9 | -2.3 | |
| Income taxes | 31.4 | 34.3 | 33.0 | 3.7 | -0.6 | 7.5 | 8.7 | |
| Other | | -33.7 | | | | | -2.0 | |
| Other operating activities | -161.5 | 14.1 | -22.6 | 1.2 | 37.7 | 5.4 | 9.3 | |
| Cash from operations | -57.9 | -35.5 | 52.8 | 58.8 | 41.9 | -13.7 | 79.6 | |
| |
| Capital expenditures [+] | -24.7 | -17.6 | -20.0 | -29.0 | -27.2 | -36.8 | -45.8 | |
| Purchases of property and equipment | -24.7 | -17.6 | -20.0 | -29.0 | -27.2 | -36.8 | -45.8 | |
| Sales of property and equipment | 7.2 | 3.5 | 2.6 | 0.9 | 2.6 | 3.3 | 4.2 | |
| Acquisitions | | | -1.0 | | | | -48.4 | |
| Other cash from investing | 260.8 | | 0.0 | | -0.4 | -0.5 | 14.1 | |
| Cash from investing | 243.4 | -14.1 | -18.3 | -28.1 | -25.0 | -34.0 | -75.8 | |
| |
| Issuance of common stock, net | 9.6 | | | | | | -2.4 | |
| Option exercises | | | | | | 0.5 | 5.9 | |
| Financing costs | -13.7 | -10.5 | -9.1 | -1.5 | -0.9 | -1.9 | -0.8 | |
| Other cash from financing | -215.3 | 81.4 | -32.6 | -38.3 | -23.9 | 24.1 | 1.4 | |
| Cash from financing | -192.0 | 91.9 | -23.5 | -36.8 | -23.0 | 25.6 | -6.0 | |
| |
| Free cash flow | -82.6 | -53.1 | 32.8 | 29.8 | 14.7 | -50.5 | 33.8 | |
| Per share (diluted) | ($19.73) | ($17.13) | $1.07 | $0.98 | $0.49 | ($1.69) | $1.20 | |
| |
| Cash paid for interest | 29.2 | 28.2 | 23.6 | 22.7 | 24.9 | 13.2 | 12.2 | |
| Cash paid for income taxes | -0.6 | 5.8 | -10.0 | -3.5 | 2.7 | 5.7 | -2.7 | |