Fair Value Measurements: Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Contract Subject to Master Netting Arrangement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 1,500	$ 1,100
Derivative Liability, Fair Value, Gross Liability	1,600	2,900
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	(1,527)	(1,085)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(1,552)	(2,909)
Fair Value, Measurements, Recurring \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Total	2,042	348
Derivative Liabilities, Total	2,044	2,345
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	3,569	1,433
Derivative Liabilities, Total	3,596	5,254
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	(1,527)	(1,085)
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	(1,552)	(2,909)
Fair Value, Measurements, Recurring \| Gas Utilities \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	977	348
Derivative, Liabilities, Fair Value Disclosure	1,123	2,345
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, Fair Value Disclosure	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, Fair Value Disclosure	2,504	1,433
Derivative, Liabilities, Fair Value Disclosure	2,675	5,254
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, Fair Value Disclosure	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
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	0
Fair Value, Measurements, Recurring \| Electric Utilities \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets, Fair Value Disclosure	1,065
Derivative, Liabilities, Fair Value Disclosure	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, Fair Value Disclosure	0
Derivative, Liabilities, Fair Value Disclosure
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, Fair Value Disclosure	1,065
Derivative, Liabilities, Fair Value Disclosure	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, Fair Value Disclosure	0
Derivative, Liabilities, Fair Value Disclosure

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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