Nature of Operations and Basis of Presentation - Additional Information (Detail)	6 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($) Segment	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Significant Accounting Policies [Line Items]
Number of segments | Segment		2
Non-cash construction advances - non-cash investing item		$ 2,800,000	$ 7,000,000
Goodwill impairment charges		0
Acquisition date adjustments to goodwill	$ 0	1,380,000
Brigadier Pipelines Inc. [Member]
Significant Accounting Policies [Line Items]
Goodwill assigned for deductible tax purpose	4,900,000	$ 4,900,000
Centuri Construction Group Inc [Member]
Significant Accounting Policies [Line Items]
Ownership percentage in subsidiary		96.60%
Centuri Construction Group Inc [Member] | W.S. Nicholls Western Construction LTD. [Member]
Significant Accounting Policies [Line Items]
Subsidiaries holding interest percentage		50.00%
Pooled funds and mutual funds [Member] | Level 2 - Significant other observable inputs [Member]
Significant Accounting Policies [Line Items]
Money market fund investments	250,000	$ 250,000		$ 250,000
Gas Pipe Materials and Supplies [Member]
Significant Accounting Policies [Line Items]
Gas pipe materials and supplies	$ 25,000,000	$ 25,000,000		$ 23,000,000