| 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 |
| | 8-K | 10-K | 10-K | 10-K | 10-K | 10-K | S-1/A |
| Net income | 40.0 | 52.7 | 44.7 | 29.5 | 25.9 | 15.0 | 14.0 |
| Depreciation and amortization [+] | | 8.9 | 9.0 | 8.8 | 8.7 | 9.9 | |
| Depreciation | | 4.5 | 5.0 | 4.7 | 4.1 | 4.2 | |
| Amortization | | 4.4 | 4.0 | 4.1 | 4.6 | 5.6 | |
| Stock-based compensation | | 3.1 | 1.9 | 1.8 | 1.8 | 0.9 | |
| Deferred taxes | | 2.8 | -4.4 | 0.3 | 0.0 | 9.7 | |
| Change in working capital [+] | | 130.9 | -26.3 | -11.0 | 12.1 | 9.6 | |
| Accrued expenses | | 5.9 | -5.5 | 2.2 | 0.8 | -6.6 | |
| Other | | 125.1 | -20.7 | -13.1 | 11.3 | 16.2 | |
| Other operating activities | | -49.2 | -47.1 | -10.2 | 5.0 | 2.8 | |
| Cash from operations | | 149.1 | -22.3 | 19.2 | 53.6 | 47.9 | |
| |
| Capital expenditures [+] | | -1.7 | -3.8 | -2.9 | -3.8 | -2.9 | |
| Purchases of property and equipment | | -1.7 | -3.8 | -2.9 | -3.8 | -2.9 | |
| Sales of property and equipment | | | | 0.9 | 0.0 | 2.4 | |
| Acquisitions | | | -9.3 | | | | |
| Purchases of short-term investments, net | | -431.1 | -269.4 | -53.6 | 12.0 | 4.0 | |
| Purchases of short-term investments | | -571.6 | -414.7 | -123.2 | -29.6 | -38.2 | |
| Sales of short-term investments | | 140.5 | 145.3 | 69.7 | 41.6 | 42.3 | |
| Other cash from investing | | 15.8 | -255.9 | -10.0 | -163.0 | -208.6 | |
| Cash from investing | | -416.9 | -538.4 | -65.6 | -154.7 | -205.1 | |
| |
| Cash dividends paid | | -10.8 | -10.4 | -8.9 | -7.5 | -6.7 | |
| Issuance of common stock, net | | -0.7 | -0.5 | 60.9 | -0.4 | -0.3 | |
| Other cash from financing | | 348.6 | 600.5 | 97.8 | 27.6 | 78.9 | |
| Cash from financing | | 337.2 | 589.6 | 149.7 | 19.8 | 71.8 | |
| |
| Free cash flow | | 147.4 | -26.1 | 16.3 | 49.8 | 44.9 | |
| Per share (diluted) | | $8.43 | ($1.50) | $1.08 | $3.54 | $3.21 | |
| |
| Cash paid for interest | | 4.5 | 12.6 | 18.4 | 12.3 | 8.0 | |
| Cash paid for income taxes | | 13.1 | 13.6 | 7.2 | 5.3 | 13.1 | |