South Dakota Public Utilities Commission (SDPUC) (Details 4) - Subsequent Event - SDPUC	Oct. 23, 2018 USD ($)
Electric rate proceeding
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ (600,000)
Natural gas rate proceeding
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ (1,300,000)

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