Condensed Financial Information - Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets:
Cash and cash equivalents	$ 46,992	$ 37,299	$ 38,227	$ 30,558
Total assets	427,452	392,647	372,229
Liabilities and Shareholders' Equity:
Total liabilities	235,864	223,686
Berkshire Hathaway shareholders' equity	187,647	164,850
Total liabilities and stockholders' equity	427,452	392,647
Berkshire Hathaway (Parent) [Member]
Assets:
Cash and cash equivalents	10,557	7,289	6,616	5,985
Investments in fixed maturity and equity securities	66	38
Investments in and advances to/from consolidated subsidiaries	185,996	166,219
Other assets	51	49
Total assets	196,670	173,595
Liabilities and Shareholders' Equity:
Accounts payable, accrued interest and other liabilities	277	129
Income taxes	423	329
Notes payable and other borrowings	8,323	8,287
Total liabilities	9,023	8,745
Berkshire Hathaway shareholders' equity	187,647	164,850
Total liabilities and stockholders' equity	$ 196,670	$ 173,595