    <SEC-DOCUMENT>0000067716-20-000060-index.html : 20201119
    <SEC-HEADER>0000067716-20-000060.hdr.sgml : 20201119
    <ACCEPTANCE-DATETIME>20201119165759
    ACCESSION NUMBER:		0000067716-20-000060
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		16
    CONFORMED PERIOD OF REPORT:	20201119
    ITEM INFORMATION:		Regulation FD Disclosure
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20201119
    DATE AS OF CHANGE:		20201119

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			MDU RESOURCES GROUP INC
    		CENTRAL INDEX KEY:			0000067716
    		STANDARD INDUSTRIAL CLASSIFICATION:	MINING, QUARRYING OF NONMETALLIC MINERALS (NO FUELS) [1400]
    		IRS NUMBER:				301133956
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-03480
    		FILM NUMBER:		201329439

    	BUSINESS ADDRESS:
    		STREET 1:		1200 WEST CENTURY AVENUE
    		CITY:			BISMARCK
    		STATE:			ND
    		ZIP:			58503
    		BUSINESS PHONE:		701-530-1000

    	MAIL ADDRESS:
    		STREET 1:		1200 WEST CENTURY AVENUE
    		CITY:			BISMARCK
    		STATE:			ND
    		ZIP:			58503

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	MONTANA DAKOTA UTILITIES CO
    		DATE OF NAME CHANGE:	19850429
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>mdu-20201119.htm
    <DESCRIPTION>MDU RESOURCES FORM 8-K CAP EX
    <TEXT>
    Document 1 - file: mdu-20201119.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99
    <SEQUENCE>2
    <FILENAME>a2020ex99-capexforecast.htm
    <DESCRIPTION>MDU RESOURCES EXHIBIT 99 CAP EX
    <TEXT>
    Document 2 - file: a2020ex99-capexforecast.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>3
    <FILENAME>mdurirpressreleasebasa181a.jpg
    <TEXT>
    Document 3 - file: mdurirpressreleasebasa181a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>4
    <FILENAME>mdu-20201119.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 4 - file: mdu-20201119.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.CAL
    <SEQUENCE>5
    <FILENAME>mdu-20201119_cal.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION CALCULATION LINKBASE DOCUMENT
    <TEXT>
    Document 5 - file: mdu-20201119_cal.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.DEF
    <SEQUENCE>6
    <FILENAME>mdu-20201119_def.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION DEFINITION LINKBASE DOCUMENT
    <TEXT>
    Document 6 - file: mdu-20201119_def.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>7
    <FILENAME>mdu-20201119_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 7 - file: mdu-20201119_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>8
    <FILENAME>mdu-20201119_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 8 - file: mdu-20201119_pre.xml

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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>9
    <FILENAME>mdu-20201119_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 9 - file: mdu-20201119_htm.html

    Document 9 - RAW XML: mdu-20201119_htm.xml

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    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>10
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 10 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>11
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 11 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>12
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 12 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>13
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 13 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>14
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 14 - file: FilingSummary.html

    Document 14 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>16
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 16 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>17
    <FILENAME>0000067716-20-000060-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 17 - file: 0000067716-20-000060-xbrl.zip

    </DOCUMENT>
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