XML 116 R108.htm IDEA: XBRL DOCUMENT v3.25.3

Business segment data - Narrative (Detail)	9 Months Ended
	Sep. 30, 2025 Activity
Segment Reporting [Abstract]
Number of insurance segment activities	2

X

- Definition

Number of insurance segment activities

+ References

No definition available.

+ Details

Name:	brka_NumberOfInsuranceSegmentActivities
Namespace Prefix:	brka_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

Name:	us-gaap_SegmentReportingAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration