Debt

9 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

Debt

Debt

Certain debt instruments of the Company and its subsidiaries contain restrictive and financial covenants and cross-default provisions. In order to borrow under the respective debt agreements, the Company and its subsidiaries must be in compliance with the applicable covenants and certain other conditions. In the event the Company or its subsidiaries do not comply with the applicable covenants and other conditions, alternative sources of funding may need to be pursued. As of September 30, 2025, the Company and its subsidiaries were in compliance with all covenants and conditions, except as otherwise noted below.

Long-term debt

Intermountain On July 15, 2025, Intermountain entered into a NPA to issue a total of $50.0 million of senior notes, with a maturity date of July 15, 2055, at an interest rate of 6.39 percent. On July 15, 2025, Intermountain issued $25.0 million in senior notes under the NPA with the remaining $25.0 million expected to be issued on November 14, 2025. This NPA is one of three distinct Intermountain NPAs that contain certain customary covenants, including a minimum interest coverage ratio. Intermountain was not in compliance with this minimum interest coverage ratio for the period ended September 30, 2025, which constituted an event of default under the terms of the Intermountain NPAs. In addition, the event of default under the terms of the Intermountain NPAs constituted a cross-default under the terms of certain NPAs of MDU Energy Capital and revolving credit agreements held by the Company and Intermountain. Subsequent to September 30, 2025, Intermountain and MDU Energy Capital obtained waivers for this non-compliance from the holders of a majority of their respective outstanding notes, and Intermountain and the Company obtained waivers from the lenders of the revolving credit agreements, which collectively cured the impact of any events of default. The Company expects to be in compliance with the minimum interest coverage ratio under the Intermountain NPAs by December 31, 2025.

Long-term Debt Outstanding Long-term debt outstanding was as follows:

	Weighted Average Interest Rate at September 30, 2025		September 30, 2025		September 30, 2024		December 31, 2024
			(In thousands)
Senior Notes due on dates ranging from October 30, 2025 to June 15, 2062	4.60	%	$	1,947,000	$	1,947,000	$	1,947,000
Credit agreements due on dates ranging from May 31, 2028 to June 20, 2029	6.06	%	183,400		163,500		169,700
Commercial paper supported by revolving credit agreement	4.40	%	132,700		57,800		81,400
Term Loan Agreements due on dates ranging from September 3, 2032 to April 1, 2039	4.44	%	60,900		123,600		65,600
Medium-Term Notes due on dates ranging from September 15, 2027 to March 16, 2029	7.32	%	35,000		35,000		35,000
Other notes due on November 30, 2038	6.00	%	333		350		346
Less unamortized debt issuance costs			6,148		6,953		6,436
Total long-term debt			2,353,185		2,320,297		2,292,610
Less current maturities			164,700		86,777		161,700
Net long-term debt			$	2,188,485	$	2,233,520	$	2,130,910