Condensed Financial Information - Balance Sheets (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets:
Cash and cash equivalents	$ 31,583	$ 28,048	$ 67,161	$ 60,033
Short-term investments in U.S. Treasury Bills	84,400
Total assets	702,095	620,854	552,257
Liabilities and Shareholders' Equity:
Income taxes, principally deferred	56,607	77,442
Total liabilities	350,141	335,426
Berkshire Hathaway shareholders' equity	348,296	282,070
Total liabilities and shareholders' equity	702,095	620,854
Berkshire Hathaway Inc. (Parent) [Member]
Assets:
Cash and cash equivalents	4,039	3,221	$ 10,609	$ 9,449
Short-term investments in U.S. Treasury Bills	13,132	8,220
Investments in fixed maturity and equity securities and other assets	79	59
Investments in and advances to/from consolidated subsidiaries	335,668	276,467
Investments in The Kraft Heinz Company	17,635	15,345
Total assets	370,553	303,312
Liabilities and Shareholders' Equity:
Accounts payable, accrued interest and other liabilities	196	182
Income taxes, principally deferred	3,294	3,357
Notes payable and other borrowings	18,767	17,703
Total liabilities	22,257	21,242
Berkshire Hathaway shareholders' equity	348,296	282,070
Total liabilities and shareholders' equity	$ 370,553	$ 303,312