| 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 |
| | 8-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | 142.6 | -106.1 | -61.2 | -88.6 | -71.9 | 42.5 | 23.0 | 20.3 |
| Depreciation and amortization [+] | | 9.4 | 8.5 | 8.4 | 8.7 | 6.3 | 4.8 | 3.3 |
| Amortization of intangible assets | | | | | | | 0.6 | 0.0 |
| Asset impairment charges | | 7.8 | 3.9 | 7.5 | 4.0 | 6.1 | | |
| Stock-based compensation | | 7.6 | 5.4 | 5.4 | 4.7 | 3.1 | 2.2 | 1.9 |
| Tax benefit from stock-based compensation | | | | | | | 0.1 | 0.0 |
| Deferred taxes | | 3.6 | -4.6 | 16.1 | -4.6 | 35.4 | 5.8 | 1.4 |
| Change in working capital | | -32.6 | 65.1 | 16.6 | -10.1 | -7.5 | -20.4 | -3.5 |
| Other | | -32.6 | 65.1 | 16.6 | -10.1 | -7.5 | -20.4 | -3.5 |
| Other operating activities | | 270.3 | 115.7 | 134.9 | 161.7 | -5.8 | 18.0 | 4.8 |
| Cash from operations | | 160.0 | 132.7 | 100.2 | 92.6 | 80.1 | 33.4 | 28.3 |
| |
| Capital expenditures | | -42.0 | -14.7 | -5.1 | -11.5 | -48.7 | -6.7 | -3.9 |
| Purchases of property and equipment | | -42.0 | -14.7 | -5.1 | -11.5 | -48.7 | -6.7 | -3.9 |
| Acquisitions | | -3.2 | 23.5 | 59.4 | -12.1 | | | |
| Purchases of short-term investments, net | | -403.4 | 30.5 | 12.4 | 38.0 | -51.8 | 62.4 | 36.3 |
| Purchases of short-term investments | | -510.1 | -77.5 | -60.2 | -33.0 | -70.0 | -10.0 | -10.0 |
| Sales of short-term investments | | 106.7 | 108.1 | 72.6 | 71.0 | 18.2 | 72.5 | 46.3 |
| Other cash from investing | | -1,029.3 | -61.4 | -238.8 | 34.2 | -354.8 | 215.9 | -127.5 |
| Cash from investing | | -1,477.8 | -22.2 | -172.1 | 48.6 | -455.2 | 271.7 | -95.1 |
| |
| Cash dividends paid | | -44.5 | -42.9 | -34.2 | -29.6 | -19.3 | -12.6 | -8.7 |
| Repurchase of common stock, net | | -36.1 | -14.8 | -26.1 | -10.8 | | -1.9 | -6.5 |
| Option exercises | | 1.9 | 1.2 | 1.3 | 5.3 | 3.4 | 4.0 | 0.4 |
| Other cash from financing | | 306.5 | 1,133.9 | 144.4 | -82.7 | 206.0 | -29.2 | 90.1 |
| Cash from financing | | 224.0 | 1,074.9 | 82.8 | -128.4 | 183.3 | -47.7 | 74.6 |
| |
| Free cash flow | | 117.9 | 117.9 | 95.2 | 81.1 | 31.4 | 26.8 | 24.4 |
| Per share (diluted) | | $1.98 | $1.96 | $1.88 | $1.70 | $0.95 | $1.14 | $1.45 |
| |
| Cash paid for interest | | 37.4 | 66.5 | 52.3 | 36.4 | 20.2 | 13.2 | 8.9 |