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Notes to Condensed Financial Statements (Details 4) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
MDU Resources Group, Inc. [Member] |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |
Cash dividends paid to parent company by consolidated subsidiaries | $ 228.4 | $ 177.1 | $ 115.9

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- References No definition available. + Details
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- Definition This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(b)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690 + Details
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Balance Type: | debit
Period Type: | duration

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- Details
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