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Regulatory liabilities (Details 2) - USD ($) $ in Thousands | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2022 | Dec. 31, 2021 | Mar. 31, 2021
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | $ 31,186 | $ 16,303 | $ 34,266
Regulatory liabilities | 433,628 | 428,790 | 429,060
Total regulatory liabilities | 464,814 | 445,093 | 463,326
Net regulatory position | $ (16,508) | 31,449 | 15,043
Natural gas costs refundable through rate adjustments |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 13,107 | 6,700 | 16,344
Taxes refundable to customers |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 3,470 | 3,841 | 3,092
Regulatory liabilities | $ 212,472 | 215,421 | 224,795
Taxes refundable to customers | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Up to 1 year |  |
Taxes refundable to customers | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Over plant lives |  |
Electric fuel and purchased power deferral |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 0 | 0 | 2,001
Other regulatory liabilities |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 14,609 | 5,762 | 12,829
Regulatory liabilities | $ 15,885 | 12,087 | 6,442
Other regulatory liabilities | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Up to 1 year |  |
Other regulatory liabilities | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Up to 20 years |  |
Plant removal and decommissioning costs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Over plant lives |  |
Regulatory liabilities | $ 171,485 | 168,152 | 169,430
Pension and postretirement benefits |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | ** |  |
Regulatory liabilities | $ 20,434 | 20,434 | 16,965
Accumulated Deferred ITC |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2022 | Up to 20 years |  |
Regulatory liabilities | $ 13,352 | $ 12,696 | $ 11,428

X
- 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 -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + 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 -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 40 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499898&loc=d3e44174-110380 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=123417213&loc=d3e43603-110378 + 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 -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394 + 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 -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394 + Details
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