Common stock (Tables)

9 Months Ended

Sep. 30, 2015

Equity [Abstract]

Changes in issued, treasury and outstanding Berkshire common stock

Changes in Berkshire’s issued, treasury and outstanding common stock during the first nine months of 2015 are shown in the table below.

	Class A, $5 Par Value (1,650,000 shares authorized)						Class B, $0.0033 Par Value (3,225,000,000 shares authorized)
	Issued		Treasury		Outstanding		Issued		Treasury		Outstanding
Balance at December 31, 2014		838,019		(11,680)		826,339		1,226,265,250		(1,409,762)		1,224,855,488
Conversions of Class A common stock to Class B common stock and exercises of replacement stock options issued in a business acquisition		(15,058)		—		(15,058)		23,255,846		—		23,255,846
Balance at September 30, 2015		822,961		(11,680)		811,281		1,249,521,096		(1,409,762)		1,248,111,334