| 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 | 8.3 | 10.5 | 8.5 | 4.2 | 8.4 | 8.6 | 9.1 | 7.9 |
| Depreciation and amortization [+] | 1.1 | 1.2 | 2.2 | 2.2 | 2.0 | 1.6 | 1.6 | 1.4 |
| Depreciation | 1.1 | 1.2 | 1.2 | 1.3 | 1.1 | 0.9 | 0.8 | 0.7 |
| Amortization of intangible assets | 0.0 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | | |
| Stock-based compensation | 0.2 | 0.1 | | 5.1 | 3.8 | 3.4 | 2.8 | 2.4 |
| Deferred taxes | -0.1 | 0.5 | -0.7 | | 0.1 | -0.2 | 0.0 | 0.3 |
| Change in working capital [+] | 1.9 | 41.9 | -39.5 | 1.7 | -0.9 | 2.1 | 1.6 | 1.4 |
| Accrued expenses | 2.8 | 42.3 | 20.3 | 1.7 | -0.8 | 1.5 | 1.7 | 1.5 |
| Other | -0.9 | -0.4 | -59.8 | 0.0 | -0.1 | 0.6 | -0.1 | 0.0 |
| Other operating activities | 28.4 | -33.0 | 31.3 | 2.1 | -1.5 | -8.6 | 0.5 | -3.7 |
| Cash from operations | 39.9 | 21.3 | 1.8 | 15.4 | 11.9 | 6.9 | 15.6 | 9.8 |
| |
| Capital expenditures [+] | -3.6 | -0.6 | -0.7 | -2.4 | -3.0 | -6.5 | -3.6 | -1.8 |
| Purchases of property and equipment | -3.6 | -0.6 | -0.7 | -2.4 | -3.0 | -6.5 | -3.6 | -1.8 |
| Sales of property and equipment | | 0.1 | | | | | | |
| Acquisitions | | | | 25.9 | | | | |
| Sales of short-term investments, net [+] | 40.8 | 25.9 | 23.7 | 3.1 | 18.5 | -2.7 | -14.9 | -3.8 |
| Purchases of short-term investments | | | -0.9 | -5.2 | -3.4 | -89.4 | -47.1 | -12.0 |
| Sales of short-term investments | 40.8 | 25.9 | 24.5 | 8.3 | 21.9 | 86.7 | 32.2 | 8.2 |
| Other cash from investing | -185.1 | -269.1 | -165.1 | -5.1 | -47.2 | -0.9 | -57.3 | -67.8 |
| Cash from investing | -147.9 | -243.7 | -142.1 | 21.5 | -31.7 | -10.0 | -75.7 | -73.4 |
| |
| Cash dividends paid | -3.6 | -3.6 | -3.6 | -3.3 | -4.3 | -3.4 | -3.1 | -2.9 |
| Repurchase of common stock, net | 0.3 | 0.3 | -0.5 | 0.3 | -1.5 | 0.1 | -0.4 | -0.1 |
| Other cash from financing | 58.1 | 235.5 | 147.0 | 31.0 | 24.6 | 2.0 | 71.5 | 52.0 |
| Cash from financing | 54.8 | 232.1 | 142.9 | 28.0 | 18.8 | -1.3 | 68.0 | 49.0 |
| |
| Free cash flow | 36.2 | 20.7 | 1.1 | 13.0 | 8.9 | 0.4 | 12.0 | 8.0 |
| Per share (diluted) | $10.51 | $6.02 | $0.32 | $3.75 | $2.47 | $0.10 | $3.24 | $2.13 |
| |
| Cash paid for interest | 7.4 | 4.1 | 5.8 | 6.8 | 4.7 | 3.9 | 3.6 | 2.9 |
| Cash paid for income taxes | 0.0 | 2.0 | 0.6 | 0.3 | 2.0 | 4.5 | 2.3 | 1.5 |