| In millions, except per share items | Sep-30-20 | Jun-30-20 | Jun-05-20 | Mar-31-20 | Mar-05-20 | Dec-31-19 | Dec-05-19 | Sep-30-19 |
| | 10-Q | 10-Q | 8-K | 10-Q | 8-K | 10-K | 8-K | 10-Q |
| Revenues: | | | | | | | | |
| Total revenues | 74.4 | 54.6 | 54.6 | 96.6 | 96.6 | 113.3 | 113.3 | 98.5 |
| Total revenues growth | -24.5% | -37.5% | -37.5% | -49.5% | -49.5% | 21.6% | 21.6% | 34.7% |
| Expenses: | | | | | | | | |
| Salaries and related employee expenses | 7.7 | 8.9 | | 10.6 | | 12.3 | | 8.5 |
| Water service-related expenses | 2.3 | 2.2 | 2.2 | 6.8 | 6.8 | 5.4 | 5.4 | 5.1 |
| General and administrative expenses | 1.9 | 2.4 | 2.4 | 3.0 | 3.0 | 2.7 | 2.7 | 2.9 |
| Legal and professional fees | 2.0 | 2.6 | 2.6 | 2.4 | 2.4 | 1.2 | 1.2 | 5.6 |
| Land sales expenses | 0.1 | | | | | | | |
| Depreciation, depletion and amortization | 3.8 | 3.7 | | 3.3 | | 3.6 | | 2.6 |
| Total operating expenses | 17.6 | 19.8 | 8.7 | 26.1 | 26.1 | 2.4 | 45.9 | 24.7 |
| Operating income | 56.7 | 34.7 | 34.7 | 70.5 | 70.5 | 88.2 | 90.4 | 73.8 |
| Operating margin | 76.3% | 63.6% | 63.6% | 73.0% | 73.0% | 77.8% | 79.7% | 74.9% |
| Other income, net | 1.3 | 0.2 | | 0.8 | 0.8 | 0.9 | 0.9 | 0.9 |
| Income before income taxes | 58.0 | 34.9 | | 71.4 | | 89.1 | | 74.8 |
| |
| Income tax expense (benefit): | | | | | | | | |
| Current | 11.1 | 8.0 | 8.0 | 14.0 | 14.0 | 14.0 | 14.0 | 9.9 |
| Deferred | 0.6 | -0.6 | -0.6 | -0.1 | -0.1 | 5.9 | 5.9 | 4.8 |
| Total income tax expense | 11.8 | 7.3 | 7.3 | 14.0 | 14.0 | 19.9 | 19.9 | 14.7 |
| Net income | 46.3 | 27.6 | | 57.4 | 57.4 | 69.1 | 71.3 | 60.0 |
| |
| Other comprehensive income — periodic pension costs, net of income taxes of $4, $2, $11 and $7, respectively | | | | | | | | |
| Total comprehensive income | 46.3 | 27.6 | | 57.4 | | 68.7 | | 60.0 |
| |
| Weighted average number of Sub-share Certificates outstanding (in shares) | 7.8 | 7.8 | | 7.8 | | 7.8 | | 7.8 |
| |
| Net income per Sub-share Certificate — basic and diluted (in dollars per share) | $5.97 | $3.56 | | $7.40 | | $8.91 | | $7.74 |
| |
| Cash dividends per Sub-share Certificate (in dollars per share) | | | | $16.00 | | | | |