| In millions, except per share items | Jun-30-23 | Mar-31-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 |
| | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
| Net income | 14.9 | 16.3 | 15.9 | 14.6 | 14.6 | 15.2 | 16.5 | 16.5 |
| Depreciation and amortization | 1.7 | 1.7 | 1.7 | 1.7 | 1.8 | 1.8 | 1.8 | 1.9 |
| Stock-based compensation | | | 0.0 | 0.0 | | | 0.1 | 0.1 |
| Deferred taxes | 0.1 | 0.3 | 0.5 | -0.2 | -0.2 | -0.4 | 0.1 | 0.6 |
| Change in working capital [+] | -1.0 | -2.3 | -2.3 | -0.3 | -0.6 | -0.8 | 1.2 | -0.3 |
| Income taxes | | | -0.1 | 0.0 | | | -0.1 | -0.4 |
| Other | -0.9 | -2.2 | -2.2 | -0.3 | -0.6 | -0.4 | 1.3 | 0.1 |
| Other operating activities | 0.6 | 2.5 | 1.0 | 8.4 | 11.9 | 8.9 | 10.6 | 7.0 |
| Cash from operations | 16.3 | 18.6 | 16.8 | 24.3 | 27.5 | 24.6 | 30.4 | 25.8 |
| |
| Capital expenditures [+] | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Sales of property and equipment | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | -0.2 | -3.2 | -3.4 |
| Purchases of short-term investments, net | 75.0 | 79.6 | 115.5 | 63.0 | -74.4 | -187.8 | -271.7 | -229.8 |
| Purchases of short-term investments | 6.9 | | | | -173.9 | -296.5 | -385.9 | -372.6 |
| Sales of short-term investments | 68.0 | 78.0 | 80.5 | 88.5 | 99.5 | 108.7 | 114.2 | 142.9 |
| Other cash from investing | -74.7 | -89.7 | -187.4 | -156.3 | -114.8 | -48.9 | -7.6 | -37.5 |
| Cash from investing | 0.5 | -9.8 | -71.6 | -93.1 | -189.0 | -236.9 | -282.5 | -270.6 |
| |
| Cash dividends paid | 0.1 | 0.0 | 0.0 | 0.1 | 0.1 | -2.2 | -4.4 | -4.3 |
| Repurchase of common stock, net | 0.4 | 0.4 | 0.4 | 0.1 | -0.3 | -0.6 | -0.8 | -0.6 |
| Other cash from financing | 0.4 | -8.3 | 56.9 | 61.7 | 122.2 | 119.6 | 231.3 | 236.4 |
| Cash from financing | 0.9 | -7.8 | 57.3 | 61.9 | 122.0 | 116.8 | 226.2 | 231.5 |
| |
| Free cash flow | 16.3 | 18.6 | 16.8 | 24.3 | 27.5 | 24.6 | 30.4 | 25.8 |
| Per share (diluted) | $4.56 | $5.20 | $4.73 | $6.83 | $7.75 | $6.93 | $8.55 | $7.26 |
| |
| Cash paid for interest | 8.9 | 11.2 | 7.7 | 5.6 | 4.6 | 4.6 | 4.8 | 5.1 |
| Cash paid for income taxes | 4.3 | 4.3 | 4.3 | 4.2 | 4.2 | 4.5 | 3.9 | 3.8 |