Significant business acquisitions - Narrative (Detail) $ in Millions		1 Months Ended	3 Months Ended
	Jan. 31, 2023 USD ($)	Jan. 31, 2024 USD ($)	Mar. 31, 2024 USD ($) Location Store	Mar. 31, 2023 USD ($)
Business Acquisition [Line Items]
Revenues			$ 61,291	$ 59,745
Net earnings attributable to Berkshire shareholders			12,702	35,504
Equity method earnings			$ 493	$ 688
Pilot Travel Centers LLC [Member]
Business Acquisition [Line Items]
Percentage of additional interest acquired	41.40%
Business acquisition, cash consideration	$ 8,200	$ 2,600
Economic interest	38.60%			38.60%
One-time, non-cash remeasurement gain recognized				$ 3,000
Economic interest after subsequent acquisition	80.00%	100.00%
Excess consideration paid for acquiring noncontrolling Interest		$ 517
Pilot Travel Centers LLC [Member] | Canadian Provinces [Member] | Travel Center Locations [Member]
Business Acquisition [Line Items]
Number of places retail locations located | Location			5
Pilot Travel Centers LLC [Member] | U.S. States [Member] | Travel Center Locations [Member]
Business Acquisition [Line Items]
Number of places retail locations located | Location			44
Pilot Travel Centers LLC [Member] | U.S. and Canada [Member]
Business Acquisition [Line Items]
Number of fuel only retail locations | Location			75
Pilot Travel Centers LLC [Member] | U.S. and Canada [Member] | Travel Center Locations [Member] | Minimum [Member]
Business Acquisition [Line Items]
Number of retail | Store			650