| 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 | -73.7 | -70.5 | 34.9 | 49.3 | 37.2 | 46.3 | 21.8 | 19.2 |
| Depreciation and amortization | 55.0 | 49.0 | 33.2 | 26.1 | 19.6 | 17.3 | 17.6 | 12.7 |
| Asset impairment charges | 61.1 | 64.2 | | 0.8 | | 1.4 | | |
| Stock-based compensation | 3.5 | 2.8 | 2.1 | 4.3 | 4.4 | 2.8 | 2.8 | 1.8 |
| Deferred taxes | -4.4 | -14.6 | 0.6 | -2.9 | -1.2 | 3.6 | -1.5 | 1.0 |
| Change in working capital [+] | 26.4 | 37.9 | -24.1 | -16.7 | 6.8 | -17.1 | -6.4 | -4.7 |
| Accounts receivable | -11.7 | 37.5 | -7.1 | -8.0 | 0.4 | -2.7 | -7.2 | -4.1 |
| Inventories | 3.9 | 2.6 | -6.0 | -11.1 | 0.5 | 0.5 | 4.5 | -3.0 |
| Other current assets | 0.2 | 2.0 | -0.5 | -0.8 | -3.4 | -1.3 | -2.3 | 0.2 |
| Accounts payable | 26.2 | -0.4 | -5.1 | 14.3 | 3.5 | -4.9 | 1.2 | -0.1 |
| Income taxes | | | | -5.2 | 0.5 | -4.8 | -3.6 | -0.7 |
| Other | 7.7 | -3.9 | -5.4 | -5.8 | 5.3 | -3.8 | 1.0 | 3.1 |
| Other operating activities | 6.4 | 18.1 | -1.9 | 2.1 | 3.0 | -18.1 | | |
| Cash from operations | 74.2 | 86.9 | 44.7 | 62.9 | 69.7 | 36.1 | 41.6 | 30.3 |
| |
| Capital expenditures [+] | -33.4 | -35.9 | -31.3 | -27.0 | -25.5 | -20.6 | -14.0 | -13.8 |
| Purchases of property and equipment | -33.4 | -35.9 | -31.3 | -27.0 | -25.5 | -20.6 | -14.0 | -13.8 |
| Sales of property and equipment | 0.0 | 0.3 | 0.3 | | | | | |
| Acquisitions | | 0.9 | -270.0 | -0.3 | -152.2 | | -79.4 | |
| Other cash from investing | 5.8 | 2.3 | | | | 28.6 | -0.1 | -0.2 |
| Cash from investing | -27.6 | -32.4 | -301.0 | -27.3 | -177.7 | 7.9 | -93.5 | -14.0 |
| |
| Repurchase of common stock, net | 1.9 | 0.3 | -0.1 | -1.4 | 0.1 | -7.2 | 1.7 | -5.1 |
| Financing costs | | | -0.5 | | | | | |
| Other cash from financing | -2.0 | -52.2 | 247.1 | -51.8 | 106.3 | -19.5 | | |
| Cash from financing | -0.1 | -51.9 | 247.5 | -53.2 | 106.4 | -26.7 | 42.5 | -5.6 |
| |
| Free cash flow | 40.7 | 51.0 | 13.4 | 35.9 | 44.3 | 15.5 | 27.7 | 16.5 |
| Per share (diluted) | $2.34 | $2.95 | $0.78 | $2.07 | $2.57 | $0.91 | $1.63 | $0.98 |
| |
| Cash paid for interest | 14.9 | 14.1 | 6.0 | 2.7 | 0.8 | 0.6 | 0.9 | 0.2 |
| Cash paid for income taxes | 3.0 | 5.9 | 4.6 | 16.2 | 15.7 | 20.2 | 14.7 | 7.2 |