| 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 | 68.7 | 81.1 | 85.0 | 84.9 | 84.9 | 86.9 | 89.3 | 69.8 |
| Depreciation and amortization [+] | 11.5 | 11.5 | 11.6 | 11.5 | 11.5 | 11.6 | 11.6 | |
| Amortization of intangible assets | 0.6 | 0.7 | 0.9 | 1.0 | 1.1 | 1.2 | 1.3 | 1.0 |
| Stock-based compensation | 4.5 | 4.4 | 4.3 | 4.4 | 4.7 | 4.9 | 5.1 | |
| Change in working capital | -0.4 | -1.3 | -1.7 | 1.2 | 4.6 | 9.1 | 8.6 | |
| Other | -0.4 | -1.3 | -1.7 | 1.2 | 4.6 | 9.1 | 8.6 | |
| Other operating activities | 12.2 | 6.4 | 4.2 | 10.1 | 16.5 | 2.3 | 6.6 | |
| Cash from operations | 96.6 | 102.2 | 103.3 | 112.1 | 122.2 | 114.8 | 121.2 | |
| |
| Capital expenditures [+] | -6.7 | -9.5 | -8.2 | -7.6 | -7.6 | -4.0 | -4.7 | |
| Purchases of property and equipment | -6.7 | -9.5 | -8.2 | -7.6 | -7.6 | -4.0 | -4.7 | |
| Sales of property and equipment | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.1 | 0.1 | |
| Purchases of short-term investments, net | 363.8 | 294.8 | 214.5 | 55.5 | -73.9 | -175.8 | -475.4 | -481.7 |
| Purchases of short-term investments | -23.7 | -30.4 | -154.8 | -224.6 | -508.3 | -683.0 | -1,071.8 | -1,002.0 |
| Sales of short-term investments | 387.5 | 325.2 | 369.3 | 280.1 | 434.4 | 507.2 | 596.4 | 520.3 |
| Other cash from investing | -185.6 | -216.9 | -215.0 | -159.5 | -157.5 | -70.4 | -103.3 | |
| Cash from investing | 171.6 | 68.5 | -8.4 | -111.5 | -238.8 | -250.0 | -583.3 | |
| |
| Cash dividends paid | -34.4 | -33.9 | -33.6 | -33.2 | -33.0 | -32.7 | -32.4 | |
| Repurchase of common stock, net | -7.7 | | | -18.0 | -29.9 | -32.6 | -23.8 | |
| Option exercises | -0.6 | -0.6 | 2.4 | 2.8 | | 2.3 | -0.8 | -0.7 |
| Other cash from financing | -225.6 | -236.8 | -28.8 | -176.5 | -28.5 | -140.6 | 192.1 | |
| Cash from financing | -267.0 | -275.2 | -80.2 | -230.6 | -94.0 | -208.2 | 136.8 | |
| |
| Free cash flow | 89.8 | 92.6 | 95.2 | 104.5 | 114.6 | 110.9 | 116.4 | |
| Per share (diluted) | $6.25 | $6.44 | $6.60 | $7.22 | $7.90 | $7.59 | $7.93 | |
| |
| Cash paid for interest | 50.0 | 33.2 | 21.0 | 12.2 | 12.2 | 14.7 | 16.9 | 15.9 |
| Cash paid for income taxes | 21.0 | 23.8 | 23.9 | 22.8 | 20.2 | 29.1 | 28.6 | 23.4 |