Revenue - Summary of Revenue Disaggregated by Service Type, and Contract Type (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 504,793	$ 552,180	$ 1,337,907	$ 1,379,596
Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	333,493	312,862	1,771,609	1,575,130
Master services agreement | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	263,545	235,655	1,411,267	1,143,603
Bid contract | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	69,948	77,207	360,342	431,527
Unit price contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	243,136	235,686	1,387,706	1,296,783
Fixed price contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	27,545	38,538	101,931	130,295
Time and materials contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	62,812	38,638	281,972	148,052
Gas infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	217,709	197,893	1,258,790	1,128,048
Electric power infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	72,320	52,301	267,736	79,528
Other | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 43,464	$ 62,668	$ 245,083	$ 367,554