| 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 | 89.8 | 83.5 | 71.5 | 65.2 | 56.6 | 58.1 | 44.7 | 41.1 |
| Depreciation and amortization | 69.0 | 62.7 | 58.1 | 45.9 | 40.8 | 36.6 | 32.2 | 30.0 |
| Stock-based compensation | 5.3 | 5.9 | 5.0 | 6.3 | 3.7 | 4.1 | 4.3 | 3.2 |
| Deferred taxes | 23.7 | 26.7 | 24.7 | 24.5 | 21.2 | 11.1 | 31.3 | 20.5 |
| Change in working capital [+] | 3.8 | -12.6 | 0.6 | -24.9 | -21.0 | -12.0 | -10.3 | -2.7 |
| Accounts receivable | -11.2 | -1.6 | -7.4 | 36.5 | -16.3 | -19.5 | -27.0 | 17.1 |
| Inventories | -7.8 | -9.5 | 1.7 | 8.2 | 2.1 | -9.0 | -2.5 | 1.5 |
| Other current assets | 9.1 | -1.5 | 2.4 | 11.1 | -7.4 | -7.0 | -1.4 | -0.8 |
| Other | 13.6 | 0.0 | 3.9 | -80.7 | 0.6 | 23.5 | 20.6 | -20.6 |
| Other operating activities | -32.7 | -15.6 | -1.1 | -13.9 | 16.1 | 12.2 | 2.1 | 12.6 |
| Cash from operations | 158.9 | 150.5 | 158.9 | 103.0 | 117.4 | 110.1 | 104.1 | 104.7 |
| |
| Capital expenditures [+] | -128.3 | -186.9 | -165.5 | -184.7 | -240.4 | -175.3 | -169.9 | -143.6 |
| Purchases of property and equipment | -128.3 | -186.9 | -165.5 | -184.7 | -240.4 | -175.3 | -169.9 | -143.6 |
| Sales of property and equipment | 3.9 | 1.0 | 8.1 | 0.4 | 0.8 | 0.7 | 0.2 | 0.2 |
| Acquisitions | -11.8 | -36.4 | -22.2 | -24.0 | -16.7 | -11.9 | | -20.9 |
| Other cash from investing | -0.3 | -0.8 | -2.0 | 21.7 | -0.6 | -0.3 | -0.4 | -0.2 |
| Cash from investing | -136.4 | -223.0 | -181.6 | -186.6 | -256.8 | -186.9 | -170.0 | -164.5 |
| |
| Cash dividends paid | -35.1 | -31.5 | -27.2 | -24.7 | -22.0 | -19.9 | -17.5 | -15.9 |
| Issuance of common stock, net | 4.5 | 15.9 | 83.6 | -0.7 | -0.7 | 0.0 | 57.4 | |
| Other cash from financing | 9.4 | 89.7 | -37.2 | 109.9 | 162.7 | 98.2 | 27.3 | 74.0 |
| Cash from financing | -21.2 | 74.0 | 19.2 | 84.5 | 140.0 | 78.2 | 67.2 | 58.1 |
| |
| Free cash flow | 30.6 | -36.4 | -6.6 | -81.8 | -123.0 | -65.2 | -65.7 | -38.9 |
| Per share (diluted) | $1.72 | ($2.07) | ($0.39) | ($4.97) | ($7.49) | ($3.98) | ($4.21) | ($2.57) |