Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 25, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3
Trading Symbol	BRKA
Entity Registrant Name	BERKSHIRE HATHAWAY INC.
Entity Central Index Key	0001067983
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		733,152
Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,362,792,906