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Fair Value Measurements: Schedule of Fair Values (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Dec. 31, 2020
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ContractSubjecttoMasterNetting |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Asset, Fair Value, Gross Asset | $ 18,000 | $ 1,500
Derivative Liability, Fair Value, Gross Liability | 100 | 1,600
Fair Value, Measurements, Recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset | (18,370) | (1,527)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset | (141) | (1,552)
Fair Value, Measurements, Recurring | Fair Value |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Total | 13,928 | 2,042
Derivative Liabilities, Total | 3,471 | 2,044
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Total | 0 | 0
Derivative Liabilities, Total | 0 | 0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Total | 32,298 | 3,569
Derivative Liabilities, Total | 3,612 | 3,596
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Total | 0 | 0
Derivative Liabilities, Total | 0 | 0
Fair Value, Measurements, Recurring | Gas Utilities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset | (18,370) | (1,527)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset | (141) | (1,552)
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 13,928 | 977
Derivative Liabilities, Fair Value Disclosure | 987 | 1,123
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value, Inputs, Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 0 | 0
Derivative Liabilities, Fair Value Disclosure | 0 | 0
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value, Inputs, Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 32,298 | 2,504
Derivative Liabilities, Fair Value Disclosure | 1,128 | 2,675
Fair Value, Measurements, Recurring | Gas Utilities | Fair Value, Inputs, Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 0 | 0
Derivative Liabilities, Fair Value Disclosure | 0 | 0
Fair Value, Measurements, Recurring | Electric Utilities |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset | 0 | 0
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset | 0 | 0
Fair Value, Measurements, Recurring | Electric Utilities | Fair Value |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 0 | 1,065
Derivative Liabilities, Fair Value Disclosure | 2,484 | 921
Fair Value, Measurements, Recurring | Electric Utilities | Fair Value, Inputs, Level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 0 | 0
Derivative Liabilities, Fair Value Disclosure | 0 | 0
Fair Value, Measurements, Recurring | Electric Utilities | Fair Value, Inputs, Level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 0 | 1,065
Derivative Liabilities, Fair Value Disclosure | 2,484 | 921
Fair Value, Measurements, Recurring | Electric Utilities | Fair Value, Inputs, Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Derivative Assets, Commodity Derivatives | 0 | 0
Derivative Liabilities, Fair Value Disclosure | $ 0 | $ 0

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