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Enviromental matters (Details 2) | 12 Months Ended
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Dec. 31, 2019 USD ($)
Portland Harbor Site |
Site Contingency [Line Items] |
Environmental matters investigative costs | $ 100,000,000
Environmental matters, estimated costs | 1,000,000,000
Missoula, MT manufactured gas plant site |
Site Contingency [Line Items] |
Total estimated costs for site remediation | 560,000
Environmental matters accrual for site remediation | 375,000
Bremerton, WA manufactured gas plant site |
Site Contingency [Line Items] |
Environmental matters accrual for site remediation | 6,400,000
Total estimated costs for site remedial investigation and feasibility study | 7,600,000
Incurred costs for site remedial investigation and feasibility study | 4,400,000
Environmental matters accrual of investigative costs | 3,200,000
Bellingham, WA manufactured gas plant site |
Site Contingency [Line Items] |
Site contingency, loss exposure not accrued, preferred alternative estimate | 9,300,000
Minimum | Bremerton, WA manufactured gas plant site |
Site Contingency [Line Items] |
Site contingency, loss exposure not accrued, best estimate | 340,000
Minimum | Bellingham, WA manufactured gas plant site |
Site Contingency [Line Items] |
Site contingency, loss exposure not accrued, best estimate | 8,000,000.0
Maximum | Bremerton, WA manufactured gas plant site |
Site Contingency [Line Items] |
Site contingency, loss exposure not accrued, best estimate | 6,400,000
Maximum | Bellingham, WA manufactured gas plant site |
Site Contingency [Line Items] |
Site contingency, loss exposure not accrued, best estimate | $ 20,400,000

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