Common stock (Tables)

6 Months Ended

Jun. 30, 2017

Equity [Abstract]

Changes in issued, treasury and outstanding Berkshire common stock

Changes in Berkshire’s issued, treasury and outstanding common stock during the first six months of 2017 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, 2016		788,058		(11,680)		776,378			1,303,323,927		(1,409,762)		1,301,914,165
Conversions of Class A common stock to Class B common stock and exercises of replacement stock options issued in a business acquisition		(8,124)		—		(8,124	)		12,609,748		—		12,609,748
Balance at June 30, 2017		779,934		(11,680)		768,254			1,315,933,675		(1,409,762)		1,314,523,913