Significant Accounting Policies - Income Taxes (Details)	12 Months Ended
Dec. 31, 2024
Accounting Policies [Abstract]
Threshold of likelihood of tax positions being realized upon ultimate settlement with a taxing authority	0.50

Threshold of likelihood that tax benefits will be realized upon ultimate settlement with a taxing authority.

No definition available.

Name:	mdu_LikelihoodOfTaxPositionsBeingRealizedUponUltimateSettlementThreshold
Namespace Prefix:	mdu_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration