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v3.19.3.a.u2

Derivative and Hedging Instruments (Details-5) | 12 Months Ended
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Dec. 31, 2019 USD ($) counterparty | Dec. 31, 2018 USD ($)
Counterparties in net liability position or default [Abstract] |  |
Derivative, net liability position of counterparties | $ 0 | $ 0
Number of counterparties in default | counterparty | 0 |
Commodity Derivative Contracts [Member] | Fuel For Electric Generation Purchased Power [Member] |  |
Realized losses (gains) on income statement [Line Items] |  |
Realized losses (gains) on income statement | $ 1,258,000 | (716,000)
Commodity Derivative Contracts [Member] | Cost Of Gas Sold Expense [Member] |  |
Realized losses (gains) on income statement [Line Items] |  |
Realized losses (gains) on income statement | 863,000 | (199,000)
Financial Transmission Rights [Member] | Fuel For Electric Generation Purchased Power [Member] |  |
Realized losses (gains) on income statement [Line Items] |  |
Realized losses (gains) on income statement | (574,000) | (702,000)
Financial Transmission Rights [Member] | Cost Of Gas Sold Expense [Member] |  |
Realized losses (gains) on income statement [Line Items] |  |
Realized losses (gains) on income statement | 0 | 0
PPA [Member] |  |
Derivative collateral required to be posted for ten-year PPA [Abstract] |  |
Minimum collateral that may be required to be posted | 20,000,000.0 |
Maximum collateral that may be required to be posted | 40,000,000.0 |
Collateral posted | 0 |
PPA [Member] | Fuel For Electric Generation Purchased Power [Member] |  |
Realized losses (gains) on income statement [Line Items] |  |
Realized losses (gains) on income statement | (2,808,000) | 1,080,000
PPA [Member] | Cost Of Gas Sold Expense [Member] |  |
Realized losses (gains) on income statement [Line Items] |  |
Realized losses (gains) on income statement | $ 0 | $ 0

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