Revenue - Summary of Information about Receivables, Revenue Earned on Contracts in Progress in Excess of Billings, Which are Included Within Accounts Receivable, Net of Allowances, and Amounts Billed in Excess of Revenue Earned on Contracts (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Contracts receivable, net	$ 187,485
Centuri Construction Group Inc [Member]
Disaggregation of Revenue [Line Items]
Contracts receivable, net	187,485	$ 221,859
Revenue earned on contracts in progress in excess of billings	86,750	5,768
Amounts billed in excess of revenue earned on contracts	$ 8,592	$ 9,602