Commitments and Contingencies Variable Interest Entities (Details) - MW	Mar. 31, 2020	Dec. 31, 2019
Independent Power Producing Entities
Variable Interest Entity [Line Items]
Generating capacity under long term purchased power agreements	1,347	1,347

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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