| 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 | -5.6 | -22.1 | -14.1 | -10.8 | 19.8 | 31.5 | 12.1 | 16.9 |
| Depreciation and amortization [+] | 148.2 | 110.5 | 88.3 | 89.1 | 85.7 | 86.9 | 76.0 | 56.9 |
| Depreciation | 135.1 | 102.7 | 86.5 | 87.0 | | | | |
| Amortization | 13.0 | 7.8 | 1.8 | 2.2 | | | | |
| Asset impairment charges | | 20.6 | | 3.3 | | | 11.4 | |
| Stock-based compensation | 7.4 | 6.6 | 5.9 | 6.4 | 6.4 | 7.0 | 6.4 | 5.0 |
| Deferred taxes | -7.5 | -6.6 | -7.3 | -2.2 | -23.2 | -13.5 | -5.6 | 17.9 |
| Change in working capital [+] | -19.0 | -41.2 | -16.0 | -15.1 | 33.9 | 6.6 | 32.2 | 6.2 |
| Accounts receivable | -19.1 | -37.9 | -17.8 | -3.5 | -1.7 | -4.1 | 2.6 | 11.7 |
| Other | 0.1 | -3.3 | 1.8 | -11.6 | 35.6 | 10.7 | 29.6 | -5.6 |
| Other operating activities | -20.5 | 12.8 | 29.5 | 17.2 | -6.7 | 27.2 | -20.9 | 36.2 |
| Cash from operations | 102.9 | 80.5 | 86.3 | 87.9 | 115.9 | 145.7 | 111.7 | 139.1 |
| |
| Capital expenditures | 7.9 | 9.7 | -60.4 | -72.7 | -105.8 | -133.8 | -124.3 | -64.8 |
| Purchases of property and equipment | 7.9 | 9.7 | -60.4 | -72.7 | -105.8 | -133.8 | -124.3 | -64.8 |
| Acquisitions | -18.0 | -340.2 | | | | -1.2 | -146.4 | -12.0 |
| Purchases of short-term investments, net | | | -0.1 | 0.1 | 6.4 | -14.3 | -7.4 | |
| Purchases of short-term investments | | | -0.1 | -8.0 | -0.1 | -18.1 | -7.4 | |
| Sales of short-term investments | | | | 8.1 | 6.6 | 3.8 | | |
| Other cash from investing | -157.1 | -96.1 | -9.7 | -15.7 | 12.0 | -23.0 | -18.5 | 44.8 |
| Cash from investing | -167.2 | -426.6 | -70.2 | -88.3 | -87.3 | -172.3 | -296.6 | -32.0 |
| |
| Cash dividends paid | -10.7 | -10.8 | -10.9 | -10.9 | -10.9 | -19.2 | -21.0 | -19.1 |
| Repurchase of common stock, net | -0.9 | -10.5 | -6.6 | -0.2 | -1.6 | -10.6 | -4.1 | -1.9 |
| Other cash from financing | 55.0 | 343.1 | -55.9 | -18.9 | -42.8 | -12.2 | 100.4 | -20.5 |
| Cash from financing | 43.4 | 321.7 | -73.4 | -29.9 | -55.2 | -42.1 | 75.3 | -41.4 |
| |
| Free cash flow | 110.8 | 90.2 | 25.9 | 15.2 | 10.1 | 11.9 | -12.6 | 74.3 |
| Per share (diluted) | $7.04 | $5.69 | $1.63 | $0.95 | $0.63 | $0.74 | ($0.78) | $4.60 |