| In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | 36.1 | 32.2 | 44.2 | 33.0 | 29.0 | 27.1 | 26.3 | 24.7 |
| Depreciation and amortization | 59.5 | 54.5 | 52.0 | 50.4 | 46.9 | | | |
| Deferred taxes | 10.8 | 9.3 | 13.5 | 8.0 | 17.5 | 15.4 | 11.9 | 14.4 |
| Change in working capital [+] | 15.0 | -13.7 | 11.3 | 5.3 | -7.2 | -4.5 | 1.5 | -0.1 |
| Accounts receivable | -4.9 | -6.9 | 11.7 | 0.6 | -14.5 | -2.6 | 14.8 | -12.7 |
| Accounts payable | 19.2 | -4.4 | -5.0 | 1.1 | 9.1 | -0.9 | -10.9 | 6.1 |
| Other | 0.7 | -2.4 | 4.6 | 3.6 | -1.8 | -1.0 | -2.4 | 6.5 |
| Other operating activities | -13.6 | -6.6 | -16.1 | -18.2 | | 30.3 | 75.4 | 45.0 |
| Cash from operations | 107.8 | 75.7 | 104.9 | 78.5 | 86.2 | 68.3 | 115.1 | 84.0 |
| |
| Capital expenditures | -115.0 | -122.6 | -119.2 | -102.4 | -119.3 | -98.1 | -103.9 | -92.6 |
| Purchases of property and equipment | -115.0 | -122.6 | -119.2 | -102.4 | -119.3 | -98.1 | -103.9 | -92.6 |
| Other cash from investing | | | 13.4 | | | | | |
| Cash from investing | -115.0 | -122.6 | -105.8 | -102.4 | -119.3 | -98.1 | -103.9 | -92.6 |
| |
| Cash dividends paid | -23.6 | -22.6 | -22.1 | -21.8 | -20.4 | -20.0 | -19.6 | -19.2 |
| Issuance of common stock, net | 45.5 | 1.1 | 1.1 | 1.2 | 33.0 | 1.3 | 1.3 | 1.2 |
| Financing costs | | -0.6 | -0.4 | -0.1 | | | | |
| Other cash from financing | -14.2 | 68.6 | 18.9 | 43.3 | 23.6 | 45.6 | 7.4 | 25.6 |
| Cash from financing | 7.7 | 47.7 | -1.7 | 22.8 | 36.2 | 26.9 | -10.9 | 7.6 |
| |
| Free cash flow | -7.2 | -46.9 | -14.3 | -23.9 | -33.1 | -29.8 | 11.2 | -8.6 |
| Per share (diluted) | ($0.47) | ($3.13) | ($0.96) | ($1.61) | ($2.35) | ($2.13) | $0.80 | ($0.62) |
| |
| Cash paid for interest | 26.0 | 23.7 | 24.1 | 24.6 | 23.0 | 22.1 | 22.3 | 20.8 |
| Cash paid for income taxes | 1.4 | 0.9 | 0.8 | 0.4 | | 1.6 | 1.8 | 1.2 |