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Risk Management and Derivatives: Utilities (Details) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2020 USD ($) MMBTU mW | Dec. 31, 2019 MMBTU mW
Derivative [Line Items] |  |
Credit Risk Derivative Liabilities, at Fair Value | $ | $ 500 |
Natural Gas, Distribution | Cash Flow Hedging |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | 1,274,900 |
Natural Gas, Distribution | Natural gas futures purchased |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | 1,930,000 | 1,450,000
Derivative, Remaining Maturity | 6 months | 12 months
Natural Gas, Distribution | Natural gas options purchased, net |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | 8,320,000 | 3,240,000
Derivative, Remaining Maturity | 6 months | 3 months
Natural Gas, Distribution | Natural gas basis swaps purchased |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | 1,780,000 | 1,290,000
Derivative, Remaining Maturity | 6 months | 12 months
Natural Gas, Distribution | Natural gas over-the-counter swaps, net |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | 4,525,100 | 4,600,000
Derivative, Remaining Maturity | 20 months | 24 months
Natural Gas, Distribution | Natural gas physical contracts, net |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | 23,350,287 | 13,548,235
Derivative, Remaining Maturity | 13 months | 12 months
Electricity | Electric wholesale contracts |  |
Derivative [Line Items] |  |
Derivative, Nonmonetary Notional Amount | mW | 55,225 | 0
Derivative, Remaining Maturity | 3 months | 0 months

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