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Regulatory liabilities (Details 2) - USD ($) $ in Thousands | 6 Months Ended |  |
--- | --- | --- | ---
Jun. 30, 2023 | Dec. 31, 2022 | Jun. 30, 2022
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | $ 48,057 | $ 26,440 | $ 17,884
Regulatory liabilities | 455,877 | 448,454 | 433,019
Total regulatory liabilities | 503,934 | 474,894 | 450,903
Net regulatory position | $ 34,413 | 19,857 | (1,307)
Natural gas costs refundable through rate adjustments |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 17,820 | 955 | 738
Electric fuel and purchased power deferral |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 8,481 | 4,929 | 4,161
Cost Recovery Mechanisms |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 3,304 | 1,977 | 3,172
Regulatory liabilities | $ 18,226 | 14,025 | 10,898
Cost Recovery Mechanisms | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 1 year |  |
Cost Recovery Mechanisms | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 19 years |  |
Conservation programs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 2,851 | 4,126 | 352
Taxes refundable to customers |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 1,513 | 3,937 | 3,728
Regulatory liabilities | $ 197,757 | 203,222 | 209,022
Taxes refundable to customers | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 1 year |  |
Taxes refundable to customers | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Over plant lives |  |
Refundable Fuel and Electric Costs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 103 | 3,253 | 1,092
Other regulatory liabilities |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 13,985 | 7,263 | 4,641
Regulatory liabilities | $ 1,694 | 1,587 | 6,649
Other regulatory liabilities | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 1 year |  |
Other regulatory liabilities | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 15 years |  |
Plant removal and decommissioning costs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Over plant lives |  |
Regulatory liabilities | $ 216,682 | 208,650 | 172,755
Accumulated Deferred ITC |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | Up to 19 years |  |
Regulatory liabilities | $ 14,398 | 13,594 | 14,009
Pension and postretirement benefits |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of June 30, 2023 | ** |  |
Regulatory liabilities | $ 7,120 | $ 7,376 | $ 19,686

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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 Describes the continual or periodic assessment of the probability of future recovery of regulatory assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482000/980-340-25-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 40 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481938/980-340-40-1 + Details
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- Definition The amount for the individual regulatory liability as itemized in a table of regulatory 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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- 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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