| 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 |
| Operating Activities | | | | | | | | |
| Net Income | 88.3 | 89.2 | 89.8 | 86.4 | 89.2 | 85.9 | 83.5 | 83.1 |
| |
| Adjustments to reconcile net income to net cash from operating activities: | | | | | | | | |
| Depreciation and amortization | 69.3 | 69.2 | 69.0 | 67.7 | 66.2 | 64.3 | 62.7 | 61.8 |
| Deferred income taxes | 18.0 | 18.8 | 23.7 | 24.8 | 25.3 | 27.7 | 26.7 | 20.6 |
| Gain on sale of discontinued operations | | | | | | | | |
| Realized gain on commodity contracts and sale of assets | -1.6 | -3.5 | -7.5 | -10.0 | -10.7 | -9.8 | -9.0 | -7.6 |
| Employee benefits and compensation | 5.4 | 5.9 | 5.3 | 5.7 | 6.0 | 6.1 | 5.9 | 5.5 |
| Share-based compensation | 5.4 | 5.9 | 5.3 | 5.7 | 6.0 | 6.1 | 5.9 | 5.5 |
| Changes in assets and liabilities: | | | | | | | | |
| Accounts receivable and accrued revenue | -5.1 | -13.1 | -11.2 | 6.6 | -0.5 | 6.4 | -1.6 | 4.8 |
| Propane inventory, storage gas and other inventory | -3.1 | -6.5 | -7.8 | -8.5 | -8.2 | -6.9 | -9.5 | -5.5 |
| Regulatory assets/liabilities, net | -3.5 | -19.8 | -38.7 | -39.4 | -32.6 | -26.8 | -18.5 | -9.3 |
| Prepaid expenses and other current assets | 1.8 | 6.5 | 9.1 | 10.8 | 6.0 | 0.9 | -1.5 | -5.5 |
| Accounts payable and other accrued liabilities | -13.3 | -8.8 | 1.5 | -14.4 | -2.2 | -5.5 | 9.5 | 26.5 |
| Income taxes receivable/payable | 11.1 | 18.9 | 14.9 | -6.2 | -4.0 | -4.5 | -4.6 | 14.2 |
| Customer deposits and refunds | 4.0 | 3.3 | 0.7 | 2.0 | 0.5 | 0.9 | 3.2 | 3.1 |
| Accrued compensation | 0.0 | -3.3 | -1.2 | -3.5 | -1.7 | -0.1 | 1.2 | 2.3 |
| Other assets and liabilities, net | 5.9 | 2.4 | 0.0 | 0.2 | -2.5 | -4.6 | 0.0 | 1.8 |
| Net cash provided by operating activities | 184.1 | 171.4 | 158.9 | 133.7 | 140.1 | 139.2 | 150.5 | 195.8 |
| |
| Investing Activities | | | | | | | | |
| Property, plant and equipment expenditures | -153.5 | -140.8 | -128.3 | -136.7 | -147.4 | -164.8 | -186.9 | -190.3 |
| Proceeds from sale of assets | 2.5 | 4.1 | 3.9 | 3.9 | 3.9 | 0.9 | 1.0 | 4.5 |
| |
| Proceeds from the sale of discontinued operations | | | | | | | | |
| Environmental expenditures | 0.1 | 0.2 | -0.3 | -0.7 | -0.7 | -0.7 | -0.8 | -3.6 |
| Net cash used in investing activities | -161.3 | -149.2 | -136.4 | -172.1 | -182.7 | -201.1 | -223.0 | -193.2 |
| |
| Financing Activities | | | | | | | | |
| Common stock dividends | -37.6 | -36.4 | -35.1 | -34.1 | -33.1 | -32.3 | -31.5 | -30.4 |
| Issuance of stock under the Dividend Reinvestment Plan, net of offering fees | 0.2 | | | 4.4 | 6.5 | 8.3 | | 48.3 |
| Tax withholding payments related to net settled stock compensation | | -2.5 | | | | -2.8 | | |
| Change in cash overdrafts due to outstanding checks | 0.0 | -0.6 | 1.0 | -0.8 | -1.3 | 0.1 | -1.2 | 1.0 |
| Net repayments under line of credit agreements | 8.5 | 3.5 | 29.3 | 35.4 | 28.0 | 43.6 | 106.1 | 64.0 |
| Repayment of long-term debt | -21.5 | -19.7 | -18.0 | -16.2 | -14.2 | -14.0 | -13.8 | |
| Net cash used in financing activities | -22.8 | -24.4 | -21.2 | 34.9 | 41.8 | 61.5 | 74.0 | 0.2 |
| Payments to Acquire Businesses, Gross | | | -11.8 | | -38.4 | | -36.4 | |