Commitments and Contingencies, Purchased Power Agreements (Details) - Independent Power Producing Entities - MW	12 Months Ended
Dec. 31, 2018	Jun. 30, 2019
Purchased Power Agreements [Abstract]
Generating capacity (in MW)	1,197	1,197
Purchase Power Agreement Expiration	2041

The expiration of purchase power agreements currently under contract (year).

No definition available.

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Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration