Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		$ 19,967	$ 13,777
Acquired finite-lived intangible assets, weighted average useful life		12 years
Goodwill		$ 44,708	38,731
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months		1,400
Amortization of intangible assets		1,300	1,200	$ 800
Amortization of intangible assets, 2020		1,100
Amortization of intangible assets, 2019		1,300
Regulated Energy
Goodwill [Line Items]
Goodwill		7,689	7,617
Unregulated Energy
Goodwill [Line Items]
Goodwill		37,019	31,114
Customer list
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	$ 16,814	10,680
Customer list | Minimum [Member]
Goodwill [Line Items]
Amortized period of acquired intangible assets		5 years
Customer list | Western Natural Gas [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		$ 1,300
Noncompete Agreements [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	2,431	$ 2,375
Noncompete Agreements [Member] | Western Natural Gas [Member]
Goodwill [Line Items]
Finite-Lived Intangible Assets, Gross		$ 100

[1] 1) The customer relationship and non-compete agreements amounts include $6.1 million and less than $0.1 million, respectively, as a result of the purchase of the operating assets of Diversified Energy in December 2021 and $1.3 million and $0.1 million, respectively, recorded as a result of the purchase of the operating assets of Western Natural Gas in October 2020.