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Regulatory liabilities (Details 2) - USD ($) $ in Thousands | 9 Months Ended |  |
--- | --- | --- | ---
Sep. 30, 2023 | Dec. 31, 2022 | Sep. 30, 2022
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | $ 45,013 | $ 26,440 | $ 18,599
Regulatory liabilities | 495,112 | 448,454 | 433,212
Total regulatory liabilities | 540,125 | 474,894 | 451,811
Net regulatory position | $ 58,092 | 19,857 | 40,791
Natural gas costs refundable through rate adjustments |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 20,445 | 955 | 873
Electric fuel and purchased power deferral |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 0 | 4,929 | 3,763
Cost Recovery Mechanisms |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 5,754 | 1,977 | 2,674
Regulatory liabilities | $ 20,012 | 14,025 | 12,535
Cost Recovery Mechanisms | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 1 year |  |
Cost Recovery Mechanisms | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 19 years |  |
Conservation programs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 1,976 | 4,126 | 325
Taxes refundable to customers |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 1,513 | 3,937 | 4,264
Regulatory liabilities | $ 194,804 | 203,222 | 205,517
Taxes refundable to customers | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 1 year |  |
Taxes refundable to customers | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Over plant lives |  |
Refundable Fuel and Electric Costs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 18 | 3,253 | 1,812
Other regulatory liabilities |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 15,307 | 7,263 | 4,888
Regulatory liabilities | $ 1,751 | 1,587 | 6,327
Other regulatory liabilities | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 1 year |  |
Other regulatory liabilities | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 15 years |  |
Plant removal and decommissioning costs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Over plant lives |  |
Regulatory liabilities | $ 220,499 | 208,650 | 174,481
Accumulated Deferred ITC |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | Up to 19 years |  |
Regulatory liabilities | $ 14,800 | 13,594 | 14,665
Pension and postretirement benefits |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of September 30, 2023 | ** |  |
Regulatory liabilities | $ 7,120 | 7,376 | 19,687
Environmental compliance programs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities | $ 36,126 | $ 0 | $ 0

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- Definition The net amount of all regulatory assets less all regulatory liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481878/980-340-50-1 + Details
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- Definition The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 405 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481854/980-405-25-1 + Details
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