| In millions, except per share items | Jun-30-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 | Jun-30-21 |
| | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q |
| Net income | 153.8 | 218.4 | 113.4 | 69.0 | -13.0 | -34.0 | -67.4 | -18.8 |
| Depreciation and amortization [+] | 32.4 | 28.4 | 27.9 | 27.6 | 27.3 | 27.7 | 27.5 | 17.1 |
| Depreciation | 32.4 | 28.4 | 27.7 | 27.3 | 27.0 | 27.0 | 25.8 | 17.1 |
| Amortization of intangible assets | | | 0.2 | 0.3 | 0.3 | 0.7 | 1.7 | |
| Asset impairment charges | | | | | 1.7 | | | 3.5 |
| Stock-based compensation | 0.1 | 2.3 | 1.7 | 1.6 | 1.1 | 1.6 | 6.6 | 1.2 |
| Change in working capital [+] | 3.1 | -52.4 | -35.3 | -52.8 | -4.7 | 0.8 | -1.3 | 4.1 |
| Accounts receivable | | -59.6 | -48.2 | -61.4 | -13.4 | -10.2 | 1.4 | -4.9 |
| Deferred revenues | | 1.6 | 1.0 | | | -0.8 | 2.1 | |
| Other | 3.1 | 5.7 | 11.9 | 8.6 | 8.7 | 11.8 | -4.8 | 9.0 |
| Other operating activities | | -15.2 | -16.4 | -10.8 | -32.2 | -23.3 | 7.9 | -8.6 |
| Cash from operations | 189.4 | 181.6 | 91.4 | 34.6 | -19.8 | -27.2 | -26.5 | -1.5 |
| |
| Capital expenditures [+] | 0.0 | 0.0 | -0.2 | -3.1 | 2.6 | -0.5 | -0.2 | -0.1 |
| Purchases of property and equipment | | 0.0 | -0.2 | -3.1 | 2.6 | -0.5 | -0.2 | -0.1 |
| Sales of property and equipment | | 28.4 | 33.8 | 15.8 | 38.0 | 33.8 | 20.1 | 20.8 |
| Purchases of short-term investments | | -25.0 | -80.0 | | | | | |
| Purchases of short-term investments | | -25.0 | -80.0 | | | | | |
| Other cash from investing | | -12.6 | -66.1 | 166.5 | -55.2 | -16.1 | 117.3 | -38.4 |
| Cash from investing | 0.0 | -9.2 | -112.5 | 179.2 | -14.6 | 17.1 | 137.2 | -17.6 |
| |
| Cash dividends paid | | -55.0 | -5.9 | -6.0 | -3.0 | -3.0 | -34.6 | -1.7 |
| Repurchase of common stock, net | | | -20.0 | | | -16.7 | | |
| Financing costs | | 0.8 | -0.2 | -0.6 | | 166.6 | -166.6 | 0.0 |
| Other cash from financing | | -48.4 | -9.4 | -52.3 | 14.1 | 162.7 | -243.7 | -18.0 |
| Cash from financing | 0.0 | -104.2 | -35.0 | -57.7 | 11.1 | -23.6 | -111.7 | -19.7 |
| |
| Free cash flow | 189.4 | 181.6 | 91.2 | 31.5 | -17.2 | -27.7 | -26.7 | -1.6 |
| Per share (diluted) | $3.83 | $3.64 | $1.83 | $0.63 | ($0.35) | ($0.72) | ($0.57) | ($0.06) |