Contingencies and Commitments - Narrative (Detail) - Subsequent Event [Member] - Berkshire Hathaway Energy [Member] - Dominion Energy, Inc. [Member] $ in Billions	1 Months Ended
	Jul. 31, 2020 USD ($) Bcfe mi
Long Term Purchase Commitment [Line Items]
Business acquisition, contingent acquisition description	to acquire substantially all of Dominion’s natural gas transmission and storage business, which includes more than 7,700 miles of natural gas transmission pipelines, about 900 billion cubic feet of operated natural gas storage capacity and partial ownership of a liquefied natural gas export, import and storage facility.
Natural gas storage capacity acquired | Bcfe	900
Business combination, contingent consideration acquisition price	$ 4.0
Business acquisition, asset-related long-term debt	$ 5.7
Minimum [Member]
Long Term Purchase Commitment [Line Items]
Business acquisition, length of pipelines acquired | mi	7,700