| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Operating Activities | | | | | | | | |
| Net Income | 89.8 | 83.5 | 71.5 | 65.2 | 56.6 | 58.1 | 44.7 | 41.1 |
| |
| Adjustments to reconcile net income to net cash from operating activities: | | | | | | | | |
| Depreciation and amortization | 69.0 | 62.7 | 58.1 | 45.9 | 40.8 | 36.6 | 32.2 | 30.0 |
| Deferred income taxes | 23.7 | 26.7 | 24.7 | 24.5 | 21.2 | 11.1 | 31.3 | 20.5 |
| Gain on sale of discontinued operations | | | | | | | | |
| Realized gain on commodity contracts and sale of assets | -7.5 | -9.0 | -6.2 | -4.1 | 5.5 | 3.2 | 0.7 | -0.3 |
| Employee benefits and compensation | 5.3 | 5.9 | 5.0 | 6.3 | 3.7 | 4.1 | 4.3 | 3.2 |
| Share-based compensation | 5.3 | 5.9 | 5.0 | 6.3 | 3.7 | 4.1 | 4.3 | 3.2 |
| Changes in assets and liabilities: | | | | | | | | |
| Accounts receivable and accrued revenue | -11.2 | -1.6 | -7.4 | 36.5 | -16.3 | -19.5 | -27.0 | 17.1 |
| Propane inventory, storage gas and other inventory | -7.8 | -9.5 | 1.7 | 8.2 | 2.1 | -9.0 | -2.5 | 1.5 |
| Regulatory assets/liabilities, net | -38.7 | -18.5 | -5.0 | -7.8 | 2.3 | -2.9 | -7.5 | 3.9 |
| Prepaid expenses and other current assets | 9.1 | -1.5 | 2.4 | 11.1 | -7.4 | -7.0 | -1.4 | -0.8 |
| Accounts payable and other accrued liabilities | 1.5 | 9.5 | 2.5 | -59.9 | 36.6 | 18.1 | 20.0 | -11.7 |
| Income taxes receivable/payable | 14.9 | -4.6 | 7.2 | -4.8 | -0.5 | 8.1 | 2.5 | -5.0 |
| Customer deposits and refunds | 0.7 | 3.2 | 2.2 | -1.8 | -0.6 | | | |
| Accrued compensation | -1.2 | 1.2 | -2.5 | 2.1 | 0.7 | 2.5 | 0.4 | -0.3 |
| Net cash provided by operating activities | 158.9 | 150.5 | 158.9 | 103.0 | 117.4 | 110.1 | 104.1 | 104.7 |
| |
| Investing Activities | | | | | | | | |
| Property, plant and equipment expenditures | -128.3 | -186.9 | -165.5 | -184.7 | -240.4 | -175.3 | -169.9 | -143.6 |
| Proceeds from sale of assets | 3.9 | 1.0 | 8.1 | 0.4 | 0.8 | 0.7 | 0.2 | 0.2 |
| |
| Proceeds from the sale of discontinued operations | | | | | | | | |
| Environmental expenditures | -0.3 | -0.8 | -2.2 | -1.2 | -0.6 | -0.3 | -0.4 | -0.2 |
| Net cash used in investing activities | -136.4 | -223.0 | -181.6 | -186.6 | -256.8 | -186.9 | -170.0 | -164.5 |
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| Financing Activities | | | | | | | | |
| Common stock dividends | -35.1 | -31.5 | -27.2 | -24.7 | -22.0 | -19.9 | -17.5 | |
| Issuance of stock under the Dividend Reinvestment Plan, net of offering fees | | | 61.0 | | | 0.0 | 57.4 | |
| Tax withholding payments related to net settled stock compensation | -2.8 | -1.5 | -1.0 | -0.7 | -1.2 | -0.7 | -0.8 | -0.6 |
| Change in cash overdrafts due to outstanding checks | 1.0 | -1.2 | -0.8 | -1.2 | -5.9 | 1.7 | 3.9 | 2.5 |
| Net repayments under line of credit agreements | 29.3 | 106.1 | 18.2 | 153.7 | 204.3 | 109.1 | 32.5 | 82.2 |
| Repayment of long-term debt | -18.0 | -13.8 | -53.6 | -41.9 | -34.4 | -12.1 | -9.1 | -10.8 |
| Net cash used in financing activities | -21.2 | 74.0 | 19.2 | 84.5 | 140.0 | 78.2 | 67.2 | 58.1 |
| Payments to Acquire Businesses, Gross | -11.8 | -36.4 | -22.2 | -24.0 | -16.7 | -11.9 | | -20.9 |