| 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 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | 61.4 | 69.0 | 59.5 | 57.2 | 53.1 | 28.5 | 40.1 | 21.0 |
| Depreciation and amortization [+] | 3.5 | 3.7 | 3.8 | 3.9 | 3.8 | 3.8 | 4.4 | 3.2 |
| Depreciation | 2.9 | 3.1 | 3.1 | 3.2 | 3.0 | 2.0 | 2.5 | 1.9 |
| Amortization of intangible assets | 0.6 | 0.7 | 0.7 | 0.7 | 0.7 | 1.8 | 1.9 | 1.3 |
| Stock-based compensation | 2.6 | 2.4 | 1.8 | 1.9 | 1.7 | 1.5 | 2.0 | 0.8 |
| Deferred taxes | 1.8 | -0.6 | -1.8 | | | | | |
| Change in working capital | -1.8 | 0.0 | 2.6 | -0.3 | 0.9 | 15.5 | -1.3 | 1.8 |
| Other | -1.8 | 0.0 | 2.6 | -0.3 | 0.9 | 15.5 | -1.3 | 1.8 |
| Other operating activities | 37.7 | 68.2 | -47.7 | -29.8 | 4.9 | 9.1 | 12.3 | -10.9 |
| Cash from operations | 105.2 | 142.7 | 18.2 | 32.9 | 64.3 | 58.3 | 57.4 | 15.9 |
| |
| Capital expenditures [+] | -2.2 | -1.9 | -2.9 | -4.3 | -5.0 | -2.8 | -1.7 | -3.2 |
| Purchases of property and equipment | -2.2 | -1.9 | -2.9 | -4.3 | -5.0 | -2.8 | -1.7 | -3.2 |
| Sales of property and equipment | 0.5 | | | | 0.7 | 0.1 | 0.1 | |
| Purchases of short-term investments, net | 174.5 | -437.2 | -169.3 | 223.3 | 14.1 | 4.8 | -35.6 | 45.3 |
| Purchases of short-term investments | -95.4 | -758.8 | -433.4 | -339.3 | -232.2 | -170.5 | -220.2 | -111.2 |
| Sales of short-term investments | 270.0 | 321.6 | 264.1 | 562.6 | 246.3 | 175.3 | 184.6 | 156.4 |
| Other cash from investing | -660.5 | -210.0 | -122.2 | -274.9 | -286.6 | -214.3 | -130.8 | -96.8 |
| Cash from investing | -487.7 | -649.1 | -294.5 | -55.8 | -276.8 | -212.1 | -168.0 | -54.7 |
| |
| Cash dividends paid | -23.5 | -21.1 | -19.8 | -18.6 | -17.2 | -14.3 | -12.4 | -9.8 |
| Repurchase of common stock, net | -10.2 | -10.1 | -9.7 | -20.8 | 0.0 | | | |
| Option exercises | 0.1 | 0.2 | 0.0 | 0.1 | 0.2 | 0.1 | 1.3 | 0.7 |
| Other cash from financing | 271.2 | 612.6 | 375.9 | 71.1 | 193.9 | 183.5 | 132.4 | 68.0 |
| Cash from financing | 237.3 | 581.2 | 346.4 | 31.6 | 176.5 | 169.1 | 118.8 | 57.5 |
| |
| Free cash flow | 103.0 | 140.9 | 15.3 | 28.6 | 59.3 | 55.5 | 55.7 | 12.7 |
| Per share (diluted) | $7.01 | $9.41 | $1.02 | $1.85 | $3.80 | $3.56 | $3.60 | $1.05 |
| |
| Cash paid for interest | 24.5 | 11.2 | 21.5 | 41.4 | 30.2 | 20.8 | 16.7 | 12.6 |