Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

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Name:	us-gaap_ShortTermBorrowings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Short-term Debt (Details 2) - USD ($) $ in Thousands	Dec. 31, 2021	Mar. 08, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Short-term borrowings	$ 0		$ 50,000
Term Loan Agreement [Member] \| Montana-Dakota Utilities Co. [Member]
Short-term Debt [Line Items]
Short-term borrowings	$ 0	$ 50,000
Ratio of total debt to total capitalization as specified in debt covenants	65.00%