| 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 | 85.6 | 77.3 | 72.6 | 82.4 | 71.4 | 156.8 | 5.7 | 0.0 |
| Depreciation and amortization | 34.8 | 29.4 | 26.3 | 23.9 | 21.5 | 20.6 | 3.8 | 0.9 |
| Asset impairment charges | | | | | 0.2 | | | |
| Stock-based compensation | 3.9 | 3.4 | 3.6 | 4.0 | 2.7 | 1.6 | 0.1 | 0.1 |
| Deferred taxes | -0.9 | | | | -0.2 | -80.7 | 1.2 | -0.2 |
| Change in working capital [+] | 13.0 | -14.4 | -9.5 | 1.0 | 4.2 | 1.1 | 7.9 | |
| Deferred revenues | | | | | | | 7.9 | |
| Other | 13.0 | -14.4 | -9.5 | 1.0 | 4.2 | 1.1 | | |
| Other operating activities | -14.1 | -4.3 | 11.7 | -30.4 | -20.9 | -28.5 | 3.0 | 0.1 |
| Cash from operations | 122.4 | 91.5 | 104.7 | 80.9 | 78.9 | 70.9 | 21.7 | 1.0 |
| |
| Capital expenditures [+] | -268.4 | -230.5 | -205.2 | -268.3 | -95.1 | -83.3 | -0.6 | -0.1 |
| Purchases of property and equipment | -268.4 | -230.5 | -205.2 | -268.3 | -95.1 | -83.3 | -0.6 | -0.1 |
| Sales of property and equipment | 3.3 | | | 21.1 | 15.6 | 24.1 | | |
| Other cash from investing | 0.1 | 1.5 | -2.2 | 0.1 | -0.9 | -0.1 | | |
| Cash from investing | -264.9 | -229.1 | -207.4 | -247.0 | -80.4 | -59.3 | -0.6 | -0.1 |
| |
| Cash dividends paid | -96.9 | -86.3 | -78.5 | -69.5 | -58.7 | -121.6 | | |
| Issuance of common stock, net | 116.5 | 151.7 | 47.2 | | | | | |
| Financing costs | -4.7 | -1.2 | | -1.5 | -5.5 | | -8.0 | |
| Other cash from financing | 113.5 | 77.0 | 45.8 | 258.0 | 97.4 | 38.6 | 69.0 | -0.9 |
| Cash from financing | 137.7 | 143.6 | 14.5 | 190.0 | 44.2 | -83.0 | 76.9 | -0.9 |
| |
| Free cash flow | -146.0 | -139.1 | -100.5 | -187.4 | -16.2 | -12.3 | 21.1 | 0.9 |
| Per share (diluted) | ($1.90) | ($1.94) | ($1.46) | ($2.91) | ($0.27) | ($0.21) | $3.37 | |
| |
| Cash paid for interest | 22.7 | 23.2 | 25.9 | 20.2 | 14.1 | 13.5 | 1.0 | |
| Cash paid for income taxes | 0.3 | 0.6 | 0.6 | 0.5 | 0.6 | 2.2 | | |