Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 27, 2018
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
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
Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		747,677
Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,346,076,963