| In millions, except per share items | Jun-30-21 | Mar-31-21 | Dec-31-20 | Sep-30-20 | Jun-30-20 | Mar-31-20 | Dec-31-19 | Sep-30-19 |
| | 10-Q | 10-Q | 10-K/A | 10-Q | 10-Q | 10-Q | 10-K/A | 10-Q |
| Net income | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.9 | 5.2 |
| Depreciation and amortization | 0.3 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 |
| Stock-based compensation | 0.9 | 0.8 | 0.8 | 0.9 | 1.1 | 1.1 | 1.1 | 1.1 |
| Deferred taxes | 0.8 | | -0.3 | -1.7 | -1.3 | 1.4 | 2.3 | 2.9 |
| Change in working capital | 95.3 | 93.0 | 93.7 | -3.3 | -1.9 | -0.2 | -7.2 | -0.8 |
| Other | 95.3 | 93.0 | 93.7 | -3.3 | -1.9 | -0.2 | -7.2 | -0.8 |
| Other operating activities | -90.5 | -85.5 | -84.5 | 11.3 | 14.7 | 11.8 | 19.6 | 11.2 |
| Cash from operations | 6.8 | 9.2 | 10.2 | 7.6 | 13.0 | 14.5 | 17.0 | 20.0 |
| |
| Capital expenditures [+] | -0.1 | -0.2 | -0.3 | -0.5 | -0.6 | -0.6 | -0.5 | -0.3 |
| Purchases of property and equipment | | -0.2 | -0.3 | -0.5 | -0.6 | -0.6 | -0.5 | -0.3 |
| Sales of property and equipment | 0.1 | 0.1 | | | 0.1 | | | |
| Sales of short-term investments, net [+] | 29.2 | -7.9 | -9.6 | -2.0 | 2.9 | -0.1 | 0.8 | 2.4 |
| Purchases of short-term investments | | -32.8 | -22.7 | -8.0 | | | -5.0 | |
| Sales of short-term investments | 62.0 | 24.9 | 13.1 | 6.0 | 8.0 | 4.9 | 5.8 | 4.4 |
| Other cash from investing | 233.0 | -102.5 | -98.1 | -116.6 | -285.0 | -74.7 | -39.0 | -83.5 |
| Cash from investing | 262.3 | -110.4 | -107.9 | -119.0 | -282.6 | -75.4 | -38.7 | -81.4 |
| |
| Option exercises | 0.7 | 0.1 | | | | 0.6 | 0.6 | 0.1 |
| Other cash from financing | -165.9 | -32.4 | 163.9 | 179.4 | 263.9 | 196.2 | 54.7 | 96.2 |
| Cash from financing | -166.6 | -32.4 | 163.8 | 178.9 | 263.4 | 195.6 | 54.1 | 96.1 |
| |
| Free cash flow | 6.7 | 9.0 | 9.9 | 7.1 | 12.3 | 13.9 | 16.5 | 19.7 |
| Per share (diluted) | $281.54 | $380.40 | $417.53 | $298.79 | $521.90 | $590.51 | $2.80 | $1.67 |
| |
| Cash paid for interest | 5.0 | 6.5 | 8.8 | 11.2 | 13.5 | 15.5 | 16.1 | 16.2 |