| 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 | 125.4 | 117.7 | 64.8 | 92.1 | 68.3 | 40.6 | 44.8 | 43.8 |
| Depreciation and amortization [+] | 12.3 | 6.4 | 6.5 | 6.9 | 7.0 | 6.8 | 6.5 | 5.9 |
| Amortization of intangible assets | 6.3 | 5.5 | 5.7 | 5.7 | 3.5 | 1.4 | 1.4 | 1.2 |
| Stock-based compensation | 3.9 | 2.6 | 2.0 | 1.7 | 1.5 | 1.6 | 1.5 | 1.4 |
| Deferred taxes | -8.0 | -0.9 | -14.2 | 1.7 | 2.6 | 12.5 | 3.2 | 0.7 |
| Change in working capital | 7.6 | 2.7 | 7.4 | -0.2 | 5.6 | -4.8 | -5.3 | 2.1 |
| Other | 7.6 | 2.7 | 7.4 | -0.2 | 5.6 | -4.8 | -5.3 | 2.1 |
| Other operating activities | 21.7 | 3.8 | 48.2 | 0.7 | 6.1 | -1.2 | -2.4 | 1.0 |
| Cash from operations | 162.9 | 132.2 | 114.8 | 102.8 | 91.1 | 55.4 | 48.2 | 54.8 |
| |
| Capital expenditures [+] | -3.6 | -3.2 | -2.8 | -4.3 | -7.4 | -15.2 | -10.9 | -5.5 |
| Purchases of property and equipment | -3.6 | -3.2 | -2.8 | -4.3 | -7.4 | -15.2 | -10.9 | -5.5 |
| Sales of property and equipment | 6.7 | 2.7 | | | | 3.3 | 1.7 | 0.0 |
| Purchases of short-term investments, net | -431.2 | -819.1 | -449.8 | 187.8 | -70.4 | -89.7 | -54.4 | -214.0 |
| Purchases of short-term investments | -699.0 | -1,190.7 | -617.6 | -37.3 | -436.7 | -265.8 | -247.7 | -341.3 |
| Sales of short-term investments | 267.8 | 371.6 | 167.7 | 225.1 | 366.3 | 176.1 | 193.4 | 127.3 |
| Other cash from investing | -295.1 | -64.3 | -363.7 | -213.3 | -64.2 | -255.9 | -75.8 | -384.9 |
| Cash from investing | -723.2 | -883.8 | -816.3 | -29.8 | -142.0 | -357.4 | -139.4 | -604.3 |
| |
| Cash dividends paid | -35.8 | -29.7 | -26.3 | -25.0 | -18.8 | -15.1 | -13.7 | -11.8 |
| Repurchase of common stock, net | -27.1 | -4.3 | -26.7 | -2.2 | -2.5 | -1.6 | -1.9 | -0.4 |
| Option exercises | 1.2 | 0.1 | 0.2 | 0.0 | 0.2 | 0.4 | 0.5 | 0.7 |
| Other cash from financing | -36.7 | 884.7 | 1,147.8 | 3.2 | 94.5 | 219.0 | 109.4 | 255.1 |
| Cash from financing | -100.9 | 850.5 | 1,094.6 | -24.0 | 73.0 | 201.9 | 93.3 | 242.2 |
| |
| Free cash flow | 159.3 | 129.0 | 112.0 | 98.5 | 83.7 | 40.2 | 37.3 | 49.3 |
| Per share (diluted) | $4.87 | $4.32 | $3.73 | $3.21 | $3.11 | $1.73 | $1.62 | $2.14 |
| |
| Cash paid for interest | 9.3 | 5.9 | 10.5 | 15.0 | 11.8 | 5.6 | 5.7 | 5.6 |
| Cash paid for income taxes | 41.0 | 46.3 | 29.5 | 35.1 | 14.5 | 21.2 | 27.6 | |