Long-Term Debt (Tables)

3 Months Ended

Mar. 31, 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 utilizes 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.

	March 31, 2015					December 31, 2014
	Carrying			Market		Carrying			Market
	Amount			Value		Amount			Value
(Thousands of dollars)
Debentures:
Notes, 4.45%, due 2020	$	125,000		$	135,578	$	125,000		$	133,403
Notes, 6.1%, due 2041		125,000			161,798		125,000			157,290
Notes, 3.875%, due 2022		250,000			267,618		250,000			262,030
Notes, 4.875%, due 2043		250,000			290,295		250,000			280,903
8% Series, due 2026		75,000			103,938		75,000			102,296
Medium-term notes, 7.59% series, due 2017		25,000			27,398		25,000			27,573
Medium-term notes, 7.78% series, due 2022		25,000			31,575		25,000			31,144
Medium-term notes, 7.92% series, due 2027		25,000			34,418		25,000			33,695
Medium-term notes, 6.76% series, due 2027		7,500			9,375		7,500			9,156
Unamortized discount		(5,135	)				(5,223	)
		902,365					902,277
Revolving credit facility and commercial paper		—			—		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			20,216		20,000			20,277
5.00% 2004 Series B, due 2033		31,200			31,329		31,200			31,223
4.85% 2005 Series A, due 2035		100,000			100,651		100,000			100,071
4.75% 2006 Series A, due 2036		24,855			25,406		24,855			25,399
Unamortized discount		(1,920	)				(1,943	)
		374,135					374,112
Centuri secured revolving credit and term loan facility		219,995			220,196		199,267			200,341
Centuri other debt obligations		28,298			28,480		31,128			31,127
		1,524,793					1,656,784
Less: current maturities		(18,266	)				(19,192	)
Long-term debt, less current maturities	$	1,506,527				$	1,637,592