General	9 Months Ended
Sep. 30, 2017
Accounting Policies [Abstract]
General	Note 1. General The accompanying unaudited Consolidated Financial Statements include the accounts of Berkshire Hathaway Inc. (“Berkshire” or “Company”) consolidated with the accounts of all its subsidiaries and affiliates in which Berkshire holds controlling financial interests as of the financial statement date. In these notes the terms “us,” “we” or “our” refer to Berkshire and its consolidated subsidiaries. Reference is made to Berkshire’s most recently issued Annual Report on Form 10-K (“Annual Report”) which includes information necessary or useful to understanding Berkshire’s businesses and financial statement presentations. Our significant accounting policies and practices were presented as Note 1 to the Consolidated Financial Statements included in the Annual Report. At December 31, 2016, we began presenting U.S. Treasury Bills with maturity dates greater than three months from their purchase dates separately in our Consolidated Balance Sheets. As of September 30, 2017, our aggregate holdings in U.S. Treasury Bills were approximately $80.6 billion, of which $66.6 billion had maturities greater than three months when acquired. Accordingly, we revised the comparative 2016 Consolidated Statement of Cash Flows to reflect this change. Financial information in this Quarterly Report reflects all adjustments (consisting only of normal recurring adjustments) that are, in the opinion of management, necessary to a fair statement of results for the interim periods in accordance with accounting principles generally accepted in the United States (“GAAP”). For a number of reasons, our results for interim periods are not normally indicative of results to be expected for the year. The timing and magnitude of catastrophe losses incurred by insurance subsidiaries and the estimation error inherent to the process of determining liabilities for unpaid losses of insurance subsidiaries can be more significant to results of interim periods than to results for a full year. Variations in the amount and timing of investment gains/losses can cause significant variations in periodic net earnings. In addition, changes in the fair values of liabilities associated with derivative contracts and gains and losses associated with the periodic revaluation of certain assets and liabilities denominated in foreign currencies can cause significant variations in periodic net earnings.

Note 1. General

The accompanying unaudited Consolidated Financial Statements include the accounts of Berkshire Hathaway Inc. (“Berkshire” or “Company”) consolidated with the accounts of all its subsidiaries and affiliates in which Berkshire holds controlling financial interests as of the financial statement date. In these notes the terms “us,” “we” or “our” refer to Berkshire and its consolidated subsidiaries. Reference is made to Berkshire’s most recently issued Annual Report on Form 10-K (“Annual Report”) which includes information necessary or useful to understanding Berkshire’s businesses and financial statement presentations. Our significant accounting policies and practices were presented as Note 1 to the Consolidated Financial Statements included in the Annual Report. At December 31, 2016, we began presenting U.S. Treasury Bills with maturity dates greater than three months from their purchase dates separately in our Consolidated Balance Sheets. As of September 30, 2017, our aggregate holdings in U.S. Treasury Bills were approximately $80.6 billion, of which $66.6 billion had maturities greater than three months when acquired. Accordingly, we revised the comparative 2016 Consolidated Statement of Cash Flows to reflect this change.

Financial information in this Quarterly Report reflects all adjustments (consisting only of normal recurring adjustments) that are, in the opinion of management, necessary to a fair statement of results for the interim periods in accordance with accounting principles generally accepted in the United States (“GAAP”). For a number of reasons, our results for interim periods are not normally indicative of results to be expected for the year. The timing and magnitude of catastrophe losses incurred by insurance subsidiaries and the estimation error inherent to the process of determining liabilities for unpaid losses of insurance subsidiaries can be more significant to results of interim periods than to results for a full year. Variations in the amount and timing of investment gains/losses can cause significant variations in periodic net earnings. In addition, changes in the fair values of liabilities associated with derivative contracts and gains and losses associated with the periodic revaluation of certain assets and liabilities denominated in foreign currencies can cause significant variations in periodic net earnings.