| 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 | 111.0 | 105.8 | 92.4 | 86.9 | 84.2 | 97.6 | 75.6 | 71.3 |
| Depreciation and amortization | | | | | 56.4 | 53.1 | | |
| Deferred taxes | | | | | 3.7 | -4.1 | | |
| Change in working capital [+] | 15.6 | 29.7 | 3.7 | -0.4 | 12.6 | -22.4 | -12.2 | 0.9 |
| Accounts receivable | 16.7 | 24.7 | 5.5 | -1.1 | -2.2 | -4.5 | -3.6 | 4.5 |
| Inventories | | | | | 2.7 | -2.6 | | |
| Other current assets | | | | | 0.3 | -2.8 | | |
| Accounts payable | | | | | -4.9 | -5.3 | | |
| Other | -1.1 | 5.0 | -1.7 | 0.7 | 16.7 | -7.3 | -8.6 | -3.7 |
| Other operating activities | 27.1 | 2.1 | 76.3 | 44.0 | -3.9 | 7.2 | 84.5 | 69.0 |
| Cash from operations | 153.7 | 137.5 | 172.4 | 130.5 | 153.0 | 131.4 | 147.9 | 141.2 |
| |
| Capital expenditures [+] | 175.0 | 153.2 | 203.1 | 164.0 | -212.2 | -108.1 | 83.7 | 72.0 |
| Purchases of property and equipment | 175.0 | 153.2 | 203.1 | 164.0 | -212.2 | -108.1 | 83.7 | 72.0 |
| Sales of property and equipment | | | | | | 2.8 | | |
| Other cash from investing | -355.2 | -310.1 | -413.6 | -336.4 | -6.1 | -11.0 | -170.5 | -145.3 |
| Cash from investing | -180.1 | -157.0 | -210.4 | -172.4 | -218.3 | -116.3 | -86.8 | -73.3 |
| |
| Cash dividends paid | 57.5 | 54.8 | 51.7 | 47.8 | -45.8 | -43.7 | 41.8 | 40.0 |
| Issuance of common stock, net | | | 79.6 | | | | | |
| Other cash from financing | -32.0 | -63.5 | -72.2 | -65.1 | 83.9 | 39.0 | -87.9 | -92.3 |
| Cash from financing | 25.5 | -8.8 | 59.2 | -17.2 | 38.1 | -4.6 | -46.1 | -52.2 |
| |
| Free cash flow | 328.8 | 290.7 | 375.6 | 294.5 | -59.2 | 23.2 | 231.5 | 213.2 |
| Per share (diluted) | $9.09 | $8.04 | $10.55 | $8.50 | ($1.71) | $0.67 | $6.68 | $6.15 |
| |
| Cash paid for interest | 26.0 | 23.5 | 23.9 | 23.2 | 20.0 | 19.2 | 19.4 | 19.6 |