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Commitments, Contingencies and Guarantees: Power Purchase Agreements (Details) - Solar - MW	Jun. 23, 2022	Mar. 21, 2022	Feb. 19, 2021
Roundhouse Renewable Energy II, LLC | Wyoming Electric
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of Megawatts Capacity Purchased	106
Purchase Power Agreement Set to Expire after a Certain Number of Years Following Completion of the Facility	20 years
South Cheyenne Solar, LLC | Wyoming Electric
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of Megawatts Capacity Purchased		150
Purchase Power Agreement Set to Expire after a Certain Number of Years Following Completion of the Facility		20 years
TC Colorado Solar, LLC | Colorado Electric
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of Megawatts Capacity Purchased			200

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