Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Oct. 26, 2020
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Entity File Number	001-14905
Entity Tax Identification Number	47-0813844
Entity Address, Address Line One	3555 Farnam Street
Entity Address, City or Town	Omaha
Entity Address, State or Province	NE
Entity Address, Postal Zip Code	68131
City Area Code	402
Local Phone Number	346-1400
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 Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Interactive Data Current	Yes
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		649,184
Security 12b Title	Class A Common Stock
Trading Symbol	BRK.A
Security Exchange Name	NYSE
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,370,951,744
Security 12b Title	Class B Common Stock
Trading Symbol	BRK.B
Security Exchange Name	NYSE
M 0.750 Senior Notes Due 2023 [Member]
Document Information [Line Items]
Security 12b Title	0.750% Senior Notes due 2023
Trading Symbol	BRK23
Security Exchange Name	NYSE
M 1.125 Senior Notes Due 2027 [Member]
Document Information [Line Items]
Security 12b Title	1.125% Senior Notes due 2027
Trading Symbol	BRK27
Security Exchange Name	NYSE
M 1.625 Senior Notes Due 2035 [Member]
Document Information [Line Items]
Security 12b Title	1.625% Senior Notes due 2035
Trading Symbol	BRK35
Security Exchange Name	NYSE
M 1.300 Senior Notes Due 2024 [Member]
Document Information [Line Items]
Security 12b Title	1.300% Senior Notes due 2024
Trading Symbol	BRK24
Security Exchange Name	NYSE
M 2.150 Senior Notes Due 2028 [Member]
Document Information [Line Items]
Security 12b Title	2.150% Senior Notes due 2028
Trading Symbol	BRK28
Security Exchange Name	NYSE
M 0.250 Senior Notes Due 2021 [Member]
Document Information [Line Items]
Security 12b Title	0.250% Senior Notes due 2021
Trading Symbol	BRK21
Security Exchange Name	NYSE
M 0.625 Senior Notes Due 2023 [Member]
Document Information [Line Items]
Security 12b Title	0.625% Senior Notes due 2023
Trading Symbol	BRK23A
Security Exchange Name	NYSE
M 0.000 Senior Notes Due 2025 [Member]
Document Information [Line Items]
Security 12b Title	0.000% Senior Notes due 2025
Trading Symbol	BRK25
Security Exchange Name	NYSE
M 2.375 Senior Notes Due 2039 [Member]
Document Information [Line Items]
Security 12b Title	2.375% Senior Notes due 2039
Trading Symbol	BRK39
Security Exchange Name	NYSE
M 2.625 Senior Notes Due 2059 [Member]
Document Information [Line Items]
Security 12b Title	2.625% Senior Notes due 2059
Trading Symbol	BRK59
Security Exchange Name	NYSE