| In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | S-1/A |
| Net income | 36.8 | 34.7 | 94.8 | 63.0 | 20.7 | 4.9 |
| Depreciation and amortization | 49.2 | 53.1 | 42.3 | 25.1 | 3.5 | |
| Stock-based compensation | 9.8 | 8.9 | 5.2 | | | |
| Deferred taxes | 9.2 | 10.0 | 26.3 | 5.8 | 4.5 | |
| Change in working capital [+] | 8.3 | -3.6 | -31.9 | 78.8 | -27.0 | |
| Accounts receivable | 1.2 | 0.9 | -1.2 | | | |
| Other | 7.1 | -4.4 | -30.7 | 78.8 | -27.0 | |
| Other operating activities | 134.8 | 126.7 | 81.5 | 0.7 | -1.6 | |
| Cash from operations | 248.1 | 229.9 | 218.2 | 173.4 | 0.0 | |
| |
| Capital expenditures [+] | -160.0 | -136.8 | -241.8 | -164.9 | 0.0 | |
| Purchases of property and equipment | -160.0 | -136.8 | -241.8 | | | |
| Capitalized product costs | | | | -164.9 | | |
| Sales of property and equipment | 80.7 | 18.7 | 0.0 | | | |
| Other cash from investing | -104.0 | -62.7 | -336.6 | | | |
| Cash from investing | -183.3 | -180.8 | -578.4 | -164.9 | 0.0 | |
| |
| Cash dividends paid | -97.1 | -115.4 | -763.2 | | | |
| Issuance of common stock, net | -47.6 | -14.7 | 719.4 | | | |
| Financing costs | | -10.0 | -4.3 | | | |
| Other cash from financing | 75.9 | 84.4 | 401.7 | 0.0 | | |
| Cash from financing | -68.8 | -35.8 | 362.2 | 0.0 | 0.0 | |
| |
| Free cash flow | 88.1 | 93.1 | -23.6 | 173.4 | 0.0 | |
| Per share (diluted) | $2.17 | $2.13 | ($0.54) | | | |
| |
| Cash paid for interest | 29.2 | 7.4 | 2.7 | | | |