Debt (Tables)

12 Months Ended

Dec. 31, 2012

Debt Disclosure [Abstract]

Outstanding credit facilities

The following table summarizes the outstanding credit facilities of the Company and its subsidiaries:

Company	Facility		Facility Limit			Amount Outstanding at December 31, 2012			Amount Outstanding at December 31, 2011			Letters of Credit at December 31, 2012			Expiration Date
			(In millions)
MDU Resources Group, Inc.	Commercial paper/Revolving credit agreement	(a)	$	125.0		$	76.0	(b)	$	—	(b)	$	—		10/4/17
Cascade Natural Gas Corporation	Revolving credit agreement		$	50.0	(c)	$	2.0		$	—		$	—		12/27/13
Intermountain Gas Company	Revolving credit agreement		$	65.0	(d)	$	26.2		$	8.1		$	—		8/11/13
Centennial Energy Holdings, Inc.	Commercial paper/Revolving credit agreement	(e)	$	500.0		$	217.0	(b)	$	—	(b)	$	20.2	(f)	6/8/17

(a) The $125 million commercial paper program is supported by a revolving credit agreement with various banks totaling $125 million (provisions allow for increased borrowings, at the option of the Company on stated conditions, up to a maximum of $150 million). There were no amounts outstanding under the credit agreement.

(b) Amount outstanding under commercial paper program.

(c) Certain provisions allow for increased borrowings, up to a maximum of $75 million.

(d) Certain provisions allow for increased borrowings, up to a maximum of $80 million.

(e) The $500 million commercial paper program is supported by a revolving credit agreement with various banks totaling $500 million (provisions allow for increased borrowings, at the option of Centennial on stated conditions, up to a maximum of $650 million). There were no amounts outstanding under the credit agreement.

(f) The outstanding letters of credit, as discussed in Note 19, reduce amounts available under the credit agreement.

Long term debt outstanding

Long-term debt outstanding at December 31 was as follows:

	2012			2011
	(In thousands)
Senior Notes at a weighted average rate of 5.74%, due on dates ranging from January 17, 2013 to May 15, 2043	$	1,349,160		$	1,287,576
Commercial paper at a weighted average rate of .51%, supported by revolving credit agreements	293,000			—
Medium-Term Notes at a weighted average rate of 7.58%, due on dates ranging from February 4, 2013 to March 16, 2029	59,000			81,000
Other notes at a weighted average rate of 5.24%, due on dates ranging from September 1, 2020 to February 1, 2035	40,090			40,469
Credit agreements at a weighted average rate of 5.22%, due on dates ranging from November 27, 2013 to November 30, 2038	3,768			15,633
Discount	(43		)	—
Total long-term debt	1,744,975			1,424,678
Less current maturities	134,108			139,267
Net long-term debt	$	1,610,867		$	1,285,411