Schedule I-Condensed Financial Information of Registrant - Condensed Balance Sheets (Parenthetical) (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Condensed Financial Statements, Captions [Line Items]
Common stock, authorized (in shares)	500,000,000	500,000,000
Common stock, par value per share (in usd per share)	$ 1.00	$ 1.00
Common stock, issued (in shares)	203,689,090	204,162,814
Treasury stock, common (in shares)		538,921
MDU Resources Group, Inc.
Condensed Financial Statements, Captions [Line Items]
Common stock, authorized (in shares)	500,000,000	500,000,000
Common stock, par value per share (in usd per share)	$ 1.00	$ 1.00
Common stock, issued (in shares)	203,689,090	204,162,814
Treasury stock, common (in shares)		538,921