Revenue - Summary of Revenue Disaggregated by Service Type, and Contract Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 241,300	$ 203,082	$ 1,068,164	$ 966,941	$ 1,440,374	$ 1,346,391
Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	632,848	580,392	1,525,448	1,408,698	2,065,038	1,877,264
Master services agreement | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	467,869	437,914	1,160,199	1,076,961	1,573,247	1,438,540
Bid contract | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	164,979	142,478	365,249	331,737	491,791	438,724
Unit price contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	406,404	377,284	1,002,779	985,673	1,373,746	1,359,352
Fixed price contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	64,632	46,379	149,681	109,935	197,447	142,356
Time and materials contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	161,812	156,729	372,988	313,090	493,845	375,556
Gas infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	393,122	387,578	961,836	935,444	1,287,552	1,288,468
Electric power infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	155,456	115,386	347,061	282,992	475,895	346,432
Other | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 84,270	$ 77,428	$ 216,551	$ 190,262	$ 301,591	$ 242,364