Long-Term Debt (Tables)

9 Months Ended

Sep. 30, 2015

Debt Disclosure [Abstract]

Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt

Since Centuri’s debt is not publicly traded, fair values for the secured revolving credit and term loan facility and other debt obligations were based on a conventional discounted cash flow methodology and utilized current market pricing yield curves, across Centuri’s debt maturity spectrum, of other industrial bonds with an assumed credit rating comparable to the Company’s.

	September 30, 2015					December 31, 2014
	Carrying Amount			Market Value		Carrying Amount			Market Value
(Thousands of dollars)
Debentures:
Notes, 4.45%, due 2020	$	125,000		$	132,769	$	125,000		$	133,403
Notes, 6.1%, due 2041		125,000			147,451		125,000			157,290
Notes, 3.875%, due 2022		250,000			263,023		250,000			262,030
Notes, 4.875%, due 2043		250,000			266,370		250,000			280,903
8% Series, due 2026		75,000			99,380		75,000			102,296
Medium-term notes, 7.59% series, due 2017		25,000			26,662		25,000			27,573
Medium-term notes, 7.78% series, due 2022		25,000			30,621		25,000			31,144
Medium-term notes, 7.92% series, due 2027		25,000			32,726		25,000			33,695
Medium-term notes, 6.76% series, due 2027		7,500			8,917		7,500			9,156
Unamortized discount		(4,957	)				(5,223	)
		902,543					902,277
Revolving credit facility and commercial paper		97,000			97,000		150,000			150,000
Industrial development revenue bonds:
Variable-rate bonds:
Tax-exempt Series A, due 2028		50,000			50,000		50,000			50,000
2003 Series A, due 2038		50,000			50,000		50,000			50,000
2008 Series A, due 2038		50,000			50,000		50,000			50,000
2009 Series A, due 2039		50,000			50,000		50,000			50,000
Fixed-rate bonds:
5.25% 2003 Series D, due 2038		—			—		20,000			20,277
5.00% 2004 Series B, due 2033		—			—		31,200			31,223
4.85% 2005 Series A, due 2035		100,000			100,415		100,000			100,071
4.75% 2006 Series A, due 2036		24,855			25,089		24,855			25,399
Unamortized discount		(1,539	)				(1,943	)
		323,316					374,112
Centuri secured revolving credit and term loan facility		208,787			209,213		199,267			200,341
Centuri other debt obligations		28,583			28,868		31,128			31,127
		1,560,229					1,656,784
Less: current maturities		(19,865	)				(19,192	)
Long-term debt, less current maturities	$	1,540,364				$	1,637,592