NDPSC (Details 3) - NDPSC - USD ($)	Jul. 19, 2019	Jan. 23, 2019
Subsequent Event [Member] | Electric rate proceeding
Public Utilities, General Disclosures [Line Items]
Public utilities, requested rate increase (decrease), amount	$ 1,500,000
Tax Cuts and Jobs Act [Member] | Natural gas rate proceeding [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount		$ (168,000)
Public Utilities, Approved One-Time Increase (Decrease) to Customers, Amount		$ (200,000)