Common stock (Tables)

12 Months Ended

Dec. 31, 2015

Equity [Abstract]

Changes in issued, treasury and outstanding Berkshire common stock

Changes in Berkshire’s issued, treasury and outstanding common stock during the three years ending December 31, 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, 2012		904,528			(9,573	)		894,955			1,123,393,956		(1,408,484	)		1,121,985,472
Conversions of Class A common stock to Class B common stock and exercises of replacement stock options issued in a business acquisition		(35,912	)		—			(35,912	)		55,381,136		—			55,381,136
Balance at December 31, 2013		868,616			(9,573	)		859,043			1,178,775,092		(1,408,484	)		1,177,366,608
Conversions of Class A common stock to Class B common stock and exercises of replacement stock options issued in a business acquisition		(30,597	)		—			(30,597	)		47,490,158		—			47,490,158
Treasury shares acquired		—			(2,107	)		(2,107	)		—		(1,278	)		(1,278	)
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		(17,917	)		—			(17,917	)		27,601,348		—			27,601,348
Balance at December 31, 2015		820,102			(11,680	)		808,422			1,253,866,598		(1,409,762	)		1,252,456,836