Nature of Operations and Basis of Presentation - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2015 USD ($) Segment	Jun. 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		$ 2,000,000	$ 5,600,000
Goodwill impairment charges		0
Acquisition date adjustments to goodwill	$ 0	$ 1,380,000
Centuri Construction Group Inc [Member] | W.S. Nicholls Western Construction LTD. [Member]
Significant Accounting Policies [Line Items]
Subsidiaries holding interest percentage	50.00%	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 Inventory and Operating Supplies [Member]
Significant Accounting Policies [Line Items]
Gas pipe inventory and operating supplies	$ 27,000,000	$ 27,000,000		$ 23,000,000