Significant business acquisitions - Pro forma consolidated earnings data (Detail) - 6 months ended Jun. 30, 2014 - AltaLink and Berkshire Hathaway Automotive [Member] - USD ($) $ / shares in Units, $ in Millions	Total
Business Acquisition [Line Items]
Revenues	$ 99,634
Net earnings attributable to Berkshire Hathaway shareholders	$ 11,174
Net earnings per equivalent Class A common share attributable to Berkshire Hathaway shareholders	$ 6,796