General	3 Months Ended
Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [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. As described in the Annual Report, we modified certain presentations to our Consolidated Financial Statements. Presentations in these interim Consolidated Financial Statements conform to the presentations in the Annual Report. Changes to those policies due to the adoption of a new accounting standard is described in Note 2. 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. In light of the size of our equity security investment portfolio, changes in market prices and the related changes in unrealized gains on equity securities will produce significant volatility in our interim and annual earnings. In addition, changes in the fair values of certain derivative contract liabilities and gains and losses from 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. As described in the Annual Report, we modified certain presentations to our Consolidated Financial Statements. Presentations in these interim Consolidated Financial Statements conform to the presentations in the Annual Report. Changes to those policies due to the adoption of a new accounting standard is described in Note 2.

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. In light of the size of our equity security investment portfolio, changes in market prices and the related changes in unrealized gains on equity securities will produce significant volatility in our interim and annual earnings. In addition, changes in the fair values of certain derivative contract liabilities and gains and losses from the periodic revaluation of certain assets and liabilities denominated in foreign currencies can cause significant variations in periodic net earnings.