New accounting pronouncements (Policies)	3 Months Ended
Mar. 31, 2016
Accounting Changes and Error Corrections [Abstract]
New accounting pronouncements	In May 2014, the FASB issued ASU 2014-09 “Revenue from Contracts with Customers.” ASU 2014-09 applies to contracts with customers, excluding, most notably, insurance and leasing contracts. ASU 2014-09 prescribes a framework in accounting for revenues from contracts within its scope, including (a) identifying the contract, (b) identifying the performance obligations under the contract, (c) determining the transaction price, (d) allocating the transaction price to the identified performance obligations and (e) recognizing revenues as the identified performance obligations are satisfied. ASU 2014-09 also prescribes additional disclosures and financial statement presentations. ASU 2014-09 is effective for reporting periods beginning after December 15, 2017, with early adoption permitted for reporting periods beginning after December 15, 2016. ASU 2014-09 may be adopted retrospectively or under a modified retrospective method where the cumulative effect is recognized at the date of initial application. Our evaluation of ASU 2014-09 is ongoing and not complete. Further, the FASB may issue interpretative guidance in the future, which may cause our evaluation to change. While we currently anticipate some relatively minor changes to revenue recognition for certain aspects of customer contracts, we do not anticipate ASU 2014-09 will have a material effect on our Consolidated Financial Statements. In May 2015, the FASB issued ASU 2015-09 “Financial Services—Insurance—Disclosures about Short-Duration Contracts,” which requires additional disclosures in annual and interim reporting periods by insurance entities regarding liabilities for unpaid claims and claim adjustment expenses, and changes in assumptions or methodologies for calculating such liabilities. ASU 2015-09 is effective for annual periods beginning after December 15, 2015 and interim periods beginning after December 15, 2016. We continue to evaluate the effect adopting this standard will have on the disclosures in our Consolidated Financial Statements. In January 2016, the FASB issued ASU 2016-01 “Financial Instruments—Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-01 generally requires that equity investments (excluding equity method investments) be measured at fair value with changes in fair value recognized in net income. ASU 2016-01 also modifies certain disclosure requirements related to financial assets and liabilities. Under existing GAAP, changes in fair value of available-for-sale equity investments are recorded in other comprehensive income. Given the current magnitude of our equity investments, the adoption of ASU 2016-01 will likely have a significant impact on the periodic net earnings reported in our Consolidated Statement of Earnings. However, the adoption of ASU 2016-01 will likely not significantly impact our comprehensive income or shareholders’ equity. ASU 2016-01 is effective for annual and interim periods beginning after December 15, 2017, with the cumulative effect of the adoption made to the balance sheet as of the date of adoption. Thus, the adoption will result in a reclassification of the related accumulated unrealized appreciation, net of applicable deferred income taxes, currently included in accumulated other comprehensive income to retained earnings, resulting in no impact on Berkshire shareholders’ equity. In February 2016, the FASB issued ASU 2016-02 “Leases.” ASU 2016-02 requires a lessee to recognize in the statement of financial position a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term, along with additional qualitative and quantitative disclosures. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, with early adoption permitted. We are currently evaluating the effect this standard will have on our Consolidated Financial Statements.

In May 2014, the FASB issued ASU 2014-09 “Revenue from Contracts with Customers.” ASU 2014-09 applies to contracts with customers, excluding, most notably, insurance and leasing contracts. ASU 2014-09 prescribes a framework in accounting for revenues from contracts within its scope, including (a) identifying the contract, (b) identifying the performance obligations under the contract, (c) determining the transaction price, (d) allocating the transaction price to the identified performance obligations and (e) recognizing revenues as the identified performance obligations are satisfied. ASU 2014-09 also prescribes additional disclosures and financial statement presentations. ASU 2014-09 is effective for reporting periods beginning after December 15, 2017, with early adoption permitted for reporting periods beginning after December 15, 2016. ASU 2014-09 may be adopted retrospectively or under a modified retrospective method where the cumulative effect is recognized at the date of initial application. Our evaluation of ASU 2014-09 is ongoing and not complete. Further, the FASB may issue interpretative guidance in the future, which may cause our evaluation to change. While we currently anticipate some relatively minor changes to revenue recognition for certain aspects of customer contracts, we do not anticipate ASU 2014-09 will have a material effect on our Consolidated Financial Statements.

In May 2015, the FASB issued ASU 2015-09 “Financial Services—Insurance—Disclosures about Short-Duration Contracts,” which requires additional disclosures in annual and interim reporting periods by insurance entities regarding liabilities for unpaid claims and claim adjustment expenses, and changes in assumptions or methodologies for calculating such liabilities. ASU 2015-09 is effective for annual periods beginning after December 15, 2015 and interim periods beginning after December 15, 2016. We continue to evaluate the effect adopting this standard will have on the disclosures in our Consolidated Financial Statements.

In January 2016, the FASB issued ASU 2016-01 “Financial Instruments—Recognition and Measurement of Financial Assets and Financial Liabilities.” ASU 2016-01 generally requires that equity investments (excluding equity method investments) be measured at fair value with changes in fair value recognized in net income. ASU 2016-01 also modifies certain disclosure requirements related to financial assets and liabilities. Under existing GAAP, changes in fair value of available-for-sale equity investments are recorded in other comprehensive income. Given the current magnitude of our equity investments, the adoption of ASU 2016-01 will likely have a significant impact on the periodic net earnings reported in our Consolidated Statement of Earnings. However, the adoption of ASU 2016-01 will likely not significantly impact our comprehensive income or shareholders’ equity. ASU 2016-01 is effective for annual and interim periods beginning after December 15, 2017, with the cumulative effect of the adoption made to the balance sheet as of the date of adoption. Thus, the adoption will result in a reclassification of the related accumulated unrealized appreciation, net of applicable deferred income taxes, currently included in accumulated other comprehensive income to retained earnings, resulting in no impact on Berkshire shareholders’ equity.

In February 2016, the FASB issued ASU 2016-02 “Leases.” ASU 2016-02 requires a lessee to recognize in the statement of financial position a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term, along with additional qualitative and quantitative disclosures. ASU 2016-02 is effective for annual periods beginning after December 15, 2018, with early adoption permitted. We are currently evaluating the effect this standard will have on our Consolidated Financial Statements.