Berkshire Hathaway (BRK-B) 10-K 1 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 16, 2021	Jun. 30, 2020
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	BERKSHIRE HATHAWAY INC
Entity Central Index Key	0001067983
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity File Number	001-14905
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-0813844
Entity Address, Address Line One	3555 Farnam Street
Entity Address, City or Town	Omaha
Entity Address, State or Province	NE
Entity Address, Postal Zip Code	68131
City Area Code	402
Local Phone Number	346-1400
Document Annual Report	true
Document Transition Report	false
Entity Public Float			$ 336,500,000,000
Documents Incorporated by Reference	Portions of the Proxy Statement for the Registrant’s Annual Meeting to be held May 1, 2021 are incorporated in Part III.
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		640,586
Security 12b Title	Class A Common Stock
Trading Symbol	BRK.A
Security Exchange Name	NYSE
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,336,348,609
Security 12b Title	Class B Common Stock
Trading Symbol	BRK.B
Security Exchange Name	NYSE
M 0.750 Senior Notes Due 2023 [Member]
Document Information [Line Items]
Security 12b Title	0.750% Senior Notes due 2023
Trading Symbol	BRK23
Security Exchange Name	NYSE
M 1.125 Senior Notes Due 2027 [Member]
Document Information [Line Items]
Security 12b Title	1.125% Senior Notes due 2027
Trading Symbol	BRK27
Security Exchange Name	NYSE
M 1.625 Senior Notes Due 2035 [Member]
Document Information [Line Items]
Security 12b Title	1.625% Senior Notes due 2035
Trading Symbol	BRK35
Security Exchange Name	NYSE
M 1.300 Senior Notes Due 2024 [Member]
Document Information [Line Items]
Security 12b Title	1.300% Senior Notes due 2024
Trading Symbol	BRK24
Security Exchange Name	NYSE
M 2.150 Senior Notes Due 2028 [Member]
Document Information [Line Items]
Security 12b Title	2.150% Senior Notes due 2028
Trading Symbol	BRK28
Security Exchange Name	NYSE
M 0.625 Senior Notes Due 2023 [Member]
Document Information [Line Items]
Security 12b Title	0.625% Senior Notes due 2023
Trading Symbol	BRK23A
Security Exchange Name	NYSE
M 0.000 Senior Notes Due 2025 [Member]
Document Information [Line Items]
Security 12b Title	0.000% Senior Notes due 2025
Trading Symbol	BRK25
Security Exchange Name	NYSE
M 2.375 Senior Notes Due 2039 [Member]
Document Information [Line Items]
Security 12b Title	2.375% Senior Notes due 2039
Trading Symbol	BRK39
Security Exchange Name	NYSE
M 0.500 Senior Notes Due 2041 [Member]
Document Information [Line Items]
Security 12b Title	0.500% Senior Notes due 2041
Trading Symbol	BRK41
Security Exchange Name	NYSE
M 2.625 Senior Notes Due 2059 [Member]
Document Information [Line Items]
Security 12b Title	2.625% Senior Notes due 2059
Trading Symbol	BRK59
Security Exchange Name	NYSE

Consolidated Balance Sheets

Consolidated Balance Sheets € in Millions, £ in Millions, $ in Millions, ¥ in Billions		Dec. 31, 2020USD ($)		Dec. 31, 2019USD ($)
ASSETS
Investments in fixed maturity securities		$ 20,410		$ 18,685
Investments in equity securities		281,170	[1]	248,027	[2]
Loans and finance receivables		19,201		17,527
Inventories		19,208		19,852
Equipment held for lease		14,601		15,065
Goodwill	[3]	73,734		81,882
Deferred charges under retroactive reinsurance contracts		12,441		13,747
Total assets		873,729		817,729
LIABILITIES
Unpaid losses and loss adjustment expenses		79,854		73,019
Unpaid losses and loss adjustment expenses under retroactive reinsurance contracts		40,966		42,441
Income taxes, principally deferred		74,098		66,799
Total liabilities		422,393		389,166
Shareholders’ equity:
Common stock		8		8
Capital in excess of par value		35,626		35,658
Accumulated other comprehensive income		(4,243)		(5,243)
Retained earnings		444,626		402,493
Treasury stock, at cost		(32,853)		(8,125)
Berkshire Hathaway shareholders’ equity		443,164		424,791
Noncontrolling interests		8,172		3,772
Total shareholders’ equity		451,336		428,563
Total liabilities and shareholders' equity		873,729		817,729
Insurance and Other [Member]
ASSETS
Cash and cash equivalents	[4]	44,714		61,151
Short-term investments in U.S. Treasury Bills		90,300		63,822
Investments in fixed maturity securities		20,410		18,685
Investments in equity securities		281,170		248,027
Equity method investments		17,303		17,505
Loans and finance receivables		19,201		17,527
Other receivables		32,310		32,418
Inventories		19,208		19,852
Property, plant and equipment		21,200		21,438
Equipment held for lease		14,601		15,065
Goodwill		47,121		57,052
Other intangible assets		29,462		31,051
Deferred charges under retroactive reinsurance contracts		12,441		13,747
Other		14,580		13,232
Total assets		664,021		630,572
LIABILITIES
Unpaid losses and loss adjustment expenses		79,854		73,019
Unpaid losses and loss adjustment expenses under retroactive reinsurance contracts		40,966		42,441
Unearned premiums		21,395		19,782
Life, annuity and health insurance benefits		21,616		20,155
Other policyholder liabilities		8,670		7,723
Accounts payable, accruals and other liabilities		29,279		27,611
Derivative contract liabilities		1,065		968
Aircraft repurchase liabilities and unearned lease revenues		5,856		5,281
Notes payable and other borrowings		41,522		37,590
Total liabilities		250,223		234,570
Railroad, Utilities and Energy [Member]
ASSETS
Cash and cash equivalents	[4]	3,276		3,024
Receivables		3,542		3,417
Property, plant and equipment		151,216		137,838
Goodwill		26,613		24,830
Regulatory assets		3,440		2,881
Other		21,621		15,167
Total assets		209,708		187,157
LIABILITIES
Accounts payable, accruals and other liabilities		15,224		14,708
Regulatory liabilities		7,475		7,311
Notes payable and other borrowings		75,373		65,778
Total liabilities		$ 98,072		$ 87,797
[1]	Approximately 68% of the aggregate fair value was concentrated in four companies (American Express Company – $18.3 billion; Apple Inc. – $120.4 billion; Bank of America Corporation – $31.3 billion and The Coca-Cola Company – $21.9 billion).
[2]	Approximately 60% of the aggregate fair value was concentrated in four companies (American Express Company – $18.9 billion; Apple Inc. – $73.7 billion; Bank of America Corporation – $33.4 billion and The Coca-Cola Company – $22.1 billion).
[3]	Net of accumulated goodwill impairments of $11.0 billion as of December 31, 2020 and $1.1 billion as of December 31, 2019.
[4]	Includes U.S. Treasury Bills with maturities of three months or less when purchased of $23.2 billion at December 31, 2020 and $37.1 billion at December 31, 2019.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
U.S. Treasury Bills [Member]
Cash equivalents	$ 23.2	$ 37.1

Consolidated Statements of Earn

Consolidated Statements of Earnings - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues:
Sales and service revenues		$ 166,733	$ 176,512	$ 175,445
Leasing revenues		5,209	5,856
Total revenues		245,510	254,616	247,837
Investment and derivative contract gains/losses:		40,746	72,607	(22,455)
Costs and expenses:
Interest expense		4,083	3,961	3,853
Total costs and expenses		231,289	225,703	219,214
Earnings before income taxes and equity method earnings (losses)		54,967	101,520	6,168
Equity method earnings (losses)		726	1,176	(2,167)
Earnings before income taxes		55,693	102,696	4,001
Income tax expense (benefit)		12,440	20,904	(321)
Net earnings		43,253	81,792	4,322
Earnings attributable to noncontrolling interests		732	375	301
Net earnings attributable to Berkshire Hathaway shareholders		$ 42,521	$ 81,417	$ 4,021
Equivalent Class A [Member]
Costs and expenses:
Net earnings per average equivalent share		$ 26,668	$ 49,828	$ 2,446
Average equivalent shares outstanding		1,594,469	1,633,946	1,643,795
Equivalent Class B [Member]
Costs and expenses:
Net earnings per average equivalent share	[1]	$ 17.78	$ 33.22	$ 1.63
Average equivalent shares outstanding		2,391,703,454	2,450,919,020	2,465,692,368
Insurance and Other [Member]
Revenues:
Insurance premiums earned		$ 63,401	$ 61,078	$ 57,418
Sales and service revenues		127,044	134,989	133,336
Leasing revenues		5,209	5,856	5,732
Interest, dividend and other investment income		8,092	9,240	7,678
Total revenues		203,746	211,163	204,164
Costs and expenses:
Insurance losses and loss adjustment expenses		43,951	44,456	39,906
Life, annuity and health insurance benefits		5,812	4,986	5,699
Insurance underwriting expenses		12,798	11,200	9,793
Cost of sales and services		101,091	107,041	106,083
Cost of leasing		3,520	4,003	4,061
Selling, general and administrative expenses		19,809	19,226	17,856
Goodwill and intangible asset impairments		10,671	96	382
Interest expense		1,105	1,056	1,035
Total costs and expenses		198,757	192,064	184,815
Freight Rail Transportation [Member]
Revenues:
Total revenues		20,750	23,357	23,703
Costs and expenses:
Expenses		13,120	15,436	16,045
Utilities and Energy [Member]
Revenues:
Sales and service revenues		15,540	15,353	15,555
Costs and expenses:
Cost of sales and other expenses		11,638	11,296	11,641
Railroad, Utilities and Energy [Member]
Revenues:
Service revenues and other income		5,474	4,743	4,415
Total revenues		41,764	43,453	43,673
Costs and expenses:
Other expenses		4,796	4,002	3,895
Interest expense		2,978	2,905	2,818
Total costs and expenses		$ 32,532	$ 33,639	$ 34,399
[1]	Class B shares are economically equivalent to one-fifteen-hundredth

Consolidated Statements of Ea_2

Consolidated Statements of Earnings (Parenthetical)	Dec. 31, 2020
Income Statement [Abstract]
Economic equivalent of Class B share to Class A share	0.0667%

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net earnings	$ 43,253	$ 81,792	$ 4,322
Other comprehensive income:
Unrealized appreciation of investments	74	142	(438)
Applicable income taxes	(19)	(31)	84
Foreign currency translation	1,284	323	(1,531)
Applicable income taxes	3	(28)	62
Defined benefit pension plans	(355)	(711)	(571)
Applicable income taxes	74	155	143
Other, net	(42)	(48)	(12)
Other comprehensive income, net	1,019	(198)	(2,263)
Comprehensive income	44,272	81,594	2,059
Comprehensive income attributable to noncontrolling interests	751	405	249
Comprehensive income attributable to Berkshire Hathaway shareholders	$ 43,521	$ 81,189	$ 1,810

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Millions	Total	Cumulative effect, period of adoption, adjustment	Common stock and capital in excess of par value	Accumulated other comprehensive income	Accumulated other comprehensive incomeCumulative effect, period of adoption, adjustment	Retained earnings	Retained earningsCumulative effect, period of adoption, adjustment	Treasury Stock	Noncontrolling interests
Beginning Balance at Dec. 31, 2017	$ 351,954	$ (70)	$ 35,702	$ 58,571	$ (61,375)	$ 255,786	$ 61,305	$ (1,763)	$ 3,658
Net earnings	4,322					4,021			301
Other comprehensive income, net	(2,263)			(2,211)					(52)
Issuance (acquisition) of common stock	(1,287)		59					(1,346)
Transactions with noncontrolling interests	(156)		(46)						(110)
Ending Balance at Dec. 31, 2018	352,500		35,715	(5,015)		321,112		(3,109)	3,797
Net earnings	81,792					81,417			375
Other comprehensive income, net	(198)			(228)					30
Issuance (acquisition) of common stock	(4,995)		21					(5,016)
Transactions with noncontrolling interests	(536)		(70)			(36)			(430)
Ending Balance at Dec. 31, 2019	428,563	$ (388)	35,666	(5,243)		402,493	$ (388)	(8,125)	3,772
Net earnings	43,253					42,521			732
Other comprehensive income, net	1,019			1,000					19
Issuance (acquisition) of common stock	(24,728)							(24,728)
Transactions with noncontrolling interests	3,617		(32)						3,649
Ending Balance at Dec. 31, 2020	$ 451,336		$ 35,634	$ (4,243)		$ 444,626		$ (32,853)	$ 8,172

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Cash flows from operating activities:
Net earnings	$ 43,253		$ 81,792		$ 4,322
Adjustments to reconcile net earnings to operating cash flows:
Investment (gains) losses	(40,905)		(71,123)		22,155
Depreciation and amortization	10,596		10,064		9,779
Other, including asset impairment charges	11,263		(1,254)		2,957
Changes in operating assets and liabilities:
Losses and loss adjustment expenses	4,819		6,087		3,449
Deferred charges reinsurance assumed	1,307		357		1,174
Unearned premiums	1,587		1,707		1,794
Receivables and originated loans	(1,609)		(2,303)		(3,443)
Other assets	(1,109)		(2,011)		(1,832)
Other liabilities	3,376		190		2,002
Income taxes	7,195		15,181		(4,957)
Net cash flows from operating activities	39,773		38,687		37,400
Cash flows from investing activities:
Purchases of equity securities	(30,161)		(18,642)		(43,210)
Sales of equity securities	38,756		14,336		18,783
Purchases of U.S. Treasury Bills and fixed maturity securities	(208,429)		(136,123)		(141,844)
Sales of U.S. Treasury Bills and fixed maturity securities	31,873		15,929		39,693
Redemptions and maturities of U.S. Treasury Bills and fixed maturity securities	149,709		137,767		113,045
Purchases of loans and finance receivables	(772)		(75)		(1,771)
Collections of loans and finance receivables	393		345		342
Acquisitions of businesses, net of cash acquired	(2,532)		(1,683)		(3,279)
Purchases of property, plant and equipment and equipment held for lease	(13,012)		(15,979)		(14,537)
Other	(3,582)		(1,496)		(71)
Net cash flows from investing activities	(37,757)		(5,621)		(32,849)
Cash flows from financing activities:
Changes in short term borrowings, net	(1,118)		266		(1,943)
Acquisition of treasury stock	(24,706)		(4,850)		(1,346)
Other	(429)		(497)		(343)
Net cash flows from financing activities	(18,344)		730		(5,812)
Effects of foreign currency exchange rate changes	92		25		(140)
Increase (decrease) in cash and cash equivalents and restricted cash	(16,236)		33,821		(1,401)
Cash and cash equivalents and restricted cash at beginning of year	64,632		30,811		32,212
Cash and cash equivalents and restricted cash at end of year	48,396		64,632		30,811
Restricted cash, included in other assets at end of year	$ 406		$ 457		$ 450
Restricted Cash and Cash Equivalents, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets		us-gaap:OtherAssets		us-gaap:OtherAssets
Insurance and Other [Member]
Cash flows from financing activities:
Proceeds from borrowings	$ 5,925		$ 8,144		$ 2,409
Repayments of borrowings	(2,700)		(5,095)		(7,395)
Cash and cash equivalents at end of year	44,714	[1]	61,151	[1]	27,749
Railroad, Utilities and Energy [Member]
Cash flows from financing activities:
Proceeds from borrowings	8,445		5,400		7,019
Repayments of borrowings	(3,761)		(2,638)		(4,213)
Cash and cash equivalents at end of year	$ 3,276	[1]	$ 3,024	[1]	$ 2,612
[1]	Includes U.S. Treasury Bills with maturities of three months or less when purchased of $23.2 billion at December 31, 2020 and $37.1 billion at December 31, 2019.

Significant accounting policies

Significant accounting policies and practices	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Significant accounting policies and practices	(1) Significant accounting (a) Nature of operations and basis of consolidation Berkshire Hathaway Inc. (“Berkshire”) is a holding company owning subsidiaries engaged in a number of diverse business activities, including insurance and reinsurance, freight rail transportation, utilities and energy, manufacturing, service and retailing. In these notes the terms “us,” “we,” or “our” refer to Berkshire and its consolidated subsidiaries. Further information regarding our reportable business segments is contained in Note 27. Information concerning business acquisitions completed over the past three years appears in Note 2. We believe that reporting the Railroad, Utilities and Energy subsidiaries separately is appropriate given the relative significance of their long-lived assets, capital expenditures and debt, which is not guaranteed by Berkshire. The accompanying Consolidated Financial Statements include the accounts of Berkshire consolidated with the accounts of all subsidiaries and affiliates in which we hold a controlling financial interest as of the financial statement date. Normally a controlling financial interest reflects ownership of a majority of the voting interests. We consolidate variable interest entities (“VIE”) when we possess both the power to direct the activities of the VIE that most significantly affect its economic performance, and we (a) are obligated to absorb the losses that could be significant to the VIE or (b) hold the right to receive benefits from the VIE that could be significant to the VIE. Intercompany accounts and transactions have been eliminated. (b) Use of estimates in preparation of financial statements We prepare our Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States (“GAAP”) which requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities at the balance sheet date and the reported amounts of revenues and expenses during the period. Our estimates of unpaid losses and loss adjustment expenses are subject to considerable estimation error due to the inherent uncertainty in projecting ultimate claim costs. In addition, estimates and assumptions associated with the amortization of deferred charges on retroactive reinsurance contracts, determinations of fair values of certain financial instruments and evaluations of goodwill and identifiable intangible assets for impairment require considerable judgment. Actual results may differ from the estimates used in preparing our Consolidated Financial Statements. The novel coronavirus (“COVID-19”) spread rapidly across the world in 2020 and was declared a pandemic by the World Health Organization. The government and private sector responses to contain its spread began to significantly affect our operating businesses in March. COVID-19 has since adversely affected nearly all of our operations, although the effects are varying significantly. The duration and extent of the effects over longer terms cannot be reasonably estimated at this time. The risks and uncertainties resulting from the pandemic that may affect our future earnings, cash flows and financial condition include the time necessary to distribute safe and effective vaccines and to vaccinate a significant number of people in the U.S. and throughout the world as well as the long-term effect from the pandemic on the demand for certain of our products and services. Accordingly, significant estimates used in the preparation of our financial statements including those associated with evaluations of certain long-lived assets, goodwill and other intangible assets for impairment, expected credit losses on amounts owed to us and the estimations of certain losses assumed under insurance and reinsurance contracts may be subject to significant adjustments in future periods. (c) Cash and cash equivalents and short-term investments in U.S. Treasury Bills Cash equivalents consist of demand deposit and money market accounts and investments (including U.S. Treasury Bills) with maturities of three months or less when purchased. Short-term investments in U.S. Treasury Bills consist of U.S. Treasury Bills with maturities exceeding three months at the time of purchase and are stated at amortized cost, which approximates fair value. Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (d) Investments in fixed maturity securities We classify investments in fixed maturity securities on the acquisition date and at each balance sheet date. Securities classified as held-to-maturity are carried at amortized cost, reflecting the ability and intent to hold the securities to maturity. Securities classified as trading are acquired with the intent to sell in the near term and are carried at fair value with changes in fair value reported in earnings. All other securities are classified as available-for-sale and are carried at fair value. Substantially all of these investments are classified as available-for-sale. We amortize the difference between the original cost and maturity value of a fixed maturity security to earnings using the interest method. We record investment gains and losses on available-for-sale fixed maturity securities when the securities are sold, as determined on a specific identification basis. For securities in an unrealized loss position, we recognize a loss in earnings for the excess of amortized cost over fair value if we intend to sell before the price recovers. Otherwise, we evaluate as of the balance sheet date whether the unrealized losses are attributable to credit losses or other factors. We consider the severity of the decline in value, creditworthiness of the issuer and other relevant factors. We record an allowance for credit losses, limited to the excess of amortized cost over fair value, along with a corresponding charge to earnings if the present value of estimated cash flows is less than the present value of contractual cash flows. The allowance may be subsequently increased or decreased based on the prevailing facts and circumstances. The portion of the unrealized loss that we believe is not related to a credit loss is recognized in other comprehensive income. (e) Investments in equity securities We carry substantially all investments in equity securities at fair value and record the subsequent changes in fair values in the Consolidated Statements of Earnings as a component of investment gains/losses. (f) Investments under the equity method We utilize the equity method to account for investments when we possess the ability to exercise significant influence, but not control, over the operating and financial policies of the investee. The ability to exercise significant influence is presumed when the investor possesses more than 20% of the voting interests of the investee. This presumption may be overcome based on specific facts and circumstances that demonstrate that the ability to exercise significant influence is restricted. We apply the equity method to investments in common stock and to other investments when such other investments possess substantially identical subordinated interests to common stock. In applying the equity method, we record the investment at cost and subsequently increase or decrease the carrying amount of the investment by our proportionate share of the net earnings or losses and other comprehensive income of the investee. We record dividends or other equity distributions as reductions in the carrying value of the investment. In the event that net losses of the investee reduce the carrying amount to zero, additional net losses may be recorded if other investments in the investee are at-risk, even if we have not committed to provide financial support to the investee. Such additional equity method losses, if any, are based upon the change in our claim on the investee’s book value. (g) Receivables Receivables primarily consist of balances due from customers, insurance premiums receivable and reinsurance losses recoverable. Trade receivables, insurance premium receivables and other receivables are primarily short-term in nature with stated collection terms of less than one year from the date of origination. Reinsurance recoverables are comprised of amounts ceded under reinsurance contracts or pursuant to mandatory government-sponsored insurance programs. Reinsurance recoverables relate to claims for unpaid losses and loss adjustment expenses arising from property and casualty contracts and claim benefits under life and health insurance contracts. Receivables are stated net of estimated allowances for uncollectible balances. Prior to 2020, we recorded provisions for uncollectible balances when it was probable counterparties or customers would be unable to pay all amounts due based on the contractual terms and historical loss history. As of January 1, 2020, we adopted a new accounting pronouncement that affects the measurement of allowances for credit losses. See Note 1(w). In measuring credit loss allowances, we primarily utilize credit loss history, with adjustments to reflect current or expected future economic conditions when reasonable and supportable forecasts of losses deviate from historical experience. In evaluating expected credit losses of reinsurance recoverable on unpaid losses, we review the credit quality of the counterparty and consider right-of-offset provisions within reinsurance contracts and other forms of credit enhancement including, collateral, guarantees and other available information. We charge-off receivables against the allowances after all reasonable collection efforts are exhausted. Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (h) Loans and finance receivables Loans and finance receivables are primarily manufactured home loans, and to lesser extent, commercial loans and site-built home loans. We carry substantially all of these loans at amortized cost, net of allowances for expected credit losses, based on our ability and intent to hold such loans to maturity. Acquisition costs and loan origination and commitment costs paid or fees received along with acquisition premiums or discounts are amortized as yield adjustments over the lives of the loans. Prior to 2020, credit losses were measured when non-collection was considered probable based on the prevailing facts and circumstances. Beginning in 2020, measurements of expected credit losses include provisions for non-collection, whether the risk is probable or remote. Expected credit losses on manufactured housing installment loans are based on the net present value of future principal payments less estimated expenses related to the charge-off and foreclosure of expected uncollectible loans and include provisions for loans that are not in foreclosure. Our principal credit quality indicator is whether the loans are performing. Expected credit loss estimates consider historical default rates, collateral recovery rates, historical runoff rates, interest rates, reductions of future cash flows for modified loans and the historical time elapsed from last payment until foreclosure, among other factors. In addition, our estimates consider current conditions and reasonable and supportable forecasts. Loans are considered delinquent when payments are more than 30 days past due. We place loans over 90 days past due on nonaccrual status and accrued but uncollected interest is reversed. Subsequent collections on the loans are first applied to the principal and interest owed for the most delinquent amount. We resume interest income accrual once a loan is less than 90 days delinquent. Loans are considered non-performing when the foreclosure process has started. Once a loan is in the process of foreclosure, interest income is not recognized unless the foreclosure is cured or the loan is modified. Once a modification is complete, interest income is recognized based on the terms of the new loan. Foreclosed loans are charged off when the collateral is sold. Loans not in foreclosure are evaluated for charge-off based on individual circumstances concerning the future collectability of the loan and the condition of the collateral securing the loan. (i) Derivatives We carry derivative contracts in our Consolidated Balance Sheets at fair value, net of reductions permitted under master netting agreements with counterparties. We record the changes in fair value of derivative contracts that do not qualify as hedging instruments for financial reporting purposes in earnings or, if such contracts involve our regulated utilities subsidiaries, as regulatory assets or liabilities when inclusion in regulated rates is probable. (j) Fair value measurements As defined under GAAP, fair value is the price that would be received to sell an asset or paid to transfer a liability between market participants in the principal market or in the most advantageous market when no principal market exists. Adjustments to transaction prices or quoted market prices may be required in illiquid or disorderly markets in estimating fair value. Alternative valuation techniques may be appropriate under the circumstances to determine the value that would be received to sell an asset or paid to transfer a liability in an orderly transaction. Market participants are assumed to be independent, knowledgeable, and able and willing to transact an exchange and not acting under duress. Our nonperformance or credit risk is considered in determining the fair value of liabilities. Considerable judgment may be required in interpreting market data used to develop the estimates of fair value. Accordingly, estimates of fair value presented herein are not necessarily indicative of the amounts that could be realized in a current or future market exchange. (k) Inventories Inventories consist of manufactured goods, goods or products acquired for resale and homes constructed for sale. Manufactured inventory costs include materials, direct and indirect labor and factory overhead. At December 31, 2020, we used the last-in-first-out (“LIFO”) method to value approximately 35% of consolidated inventories with the remainder primarily determined under first-in-first-out and average cost methods. Non-LIFO inventories are stated at the lower of cost or net realizable value. The excess of current or replacement costs over costs determined under LIFO was approximately $1.1 billion as of December 31, 2020 and $950 million as of December 31, 2019. Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (l) Property, plant and equipment We record additions to property, plant and equipment used in operations at cost, which includes asset additions, improvements and betterments. With respect to constructed assets, all materials, direct labor and contract services as well as certain indirect costs are capitalized. Indirect costs include interest over the construction period. With respect to constructed assets of our utility and energy subsidiaries that are subject to authoritative guidance for regulated operations, capitalized costs also include an allowance for funds used during construction, which represents the cost of equity funds used to finance the construction of the regulated facilities. Normal repairs and maintenance and other costs that do not improve the property, extend useful lives or otherwise do not meet capitalization criteria are charged to expense as incurred. Depreciation of assets of our regulated utilities and railroad is generally determined using group depreciation methods where rates are based on periodic depreciation studies approved by the applicable regulator. Under group depreciation, a composite rate is applied to the gross investment in a particular class of property, despite differences in the service life or salvage value of individual property units within the same class. When such assets are retired or sold, no gain or loss is recognized. Gains or losses on disposals of all other assets are recorded through earnings. We depreciate property, plant and equipment used by our other businesses to estimated salvage value primarily using the straight-line method over estimated useful lives. Ranges of estimated useful lives of depreciable assets used in our other businesses are as follows: buildings and improvements – 5 to 50 years, machinery and equipment – 3 to 25 years and furniture, fixtures and other – 3 to 15 years. Ranges of estimated useful lives of depreciable assets unique to our railroad business are as follows: track structure and other roadway – 10 to 100 years and locomotives, freight cars and other equipment – 6 to 43 years. Ranges of estimated useful lives of assets unique to our regulated utilities and energy businesses are as follows: utility generation, transmission and distribution systems – 5 to 80 years, interstate natural gas pipeline assets – 3 to 80 years and independent power plants and other assets – 3 to 40 years. We evaluate property, plant and equipment for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable or when the assets are held for sale. Upon the occurrence of a triggering event, we assess whether the estimated undiscounted cash flows expected from the use of the asset and the residual value from the ultimate disposal of the asset exceeds the carrying value. If the carrying value exceeds the estimated recoverable amounts, we reduce the carrying value to fair value and record an impairment loss in earnings, except with respect to impairment of assets of our regulated utility and energy subsidiaries where the impacts of regulation are considered in evaluating the carrying value. (m) Leases We are party to contracts where we lease property to others (“lessor” contracts) and where we lease property from others (“lessee” contracts). We record acquisitions of and additions to equipment that we lease to others at cost. We depreciate equipment held for lease to estimated salvage value primarily using the straight-line method over estimated useful lives ranging from 3 to 35 years. We use declining balance deprecation methods for assets when the revenue-earning power of the asset is relatively greater during the earlier years of its life and maintenance and repair costs increase during the later years. We also evaluate equipment held for lease for impairment consistent with policies for property, plant and equipment. When we lease assets from others, we record right-of-use assets and lease liabilities. Right-of-use assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. In this regard, lease payments include fixed payments and variable payments that depend on an index or rate. The lease term is generally the non-cancellable lease period. Certain lease contracts contain renewal options or other terms that provide for variable payments based on performance or usage. Options are not included in determining right-of-use assets or lease liabilities unless it is reasonably certain that options will be exercised. Generally, incremental borrowing rates are used in measuring lease liabilities. Right-of-use assets are subject to review for impairment. Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (n) Goodwill and other intangible assets Goodwill represents the excess of the acquisition price of a business over the fair value of identified net assets of that business. We evaluate goodwill for impairment at least annually. When evaluating goodwill for impairment, we estimate the fair value of the reporting unit. Several methods may be used to estimate a reporting unit’s fair value, including market quotations, asset and liability fair values and other valuation techniques, including, but not limited to, discounted projected future net earnings or net cash flows and multiples of earnings. If the carrying amount of a reporting unit, including goodwill, exceeds the estimated fair value, then the excess is charged to earnings as an impairment loss. Intangible assets with indefinite lives are also tested for impairment at least annually and when events or changes in circumstances indicate that, more-likely-than-not, the asset is impaired. Significant judgment is required in estimating fair values and performing goodwill and indefinite-life intangible asset impairment tests. We amortize intangible assets with finite lives in a pattern that reflects the expected consumption of related economic benefits or on a straight-line basis over the estimated economic useful lives. Intangible assets with finite lives are reviewed for impairment when events or changes in circumstances indicate that the carrying amount may not be recoverable. (o) Revenue recognition We earn insurance premiums on prospective property/casualty insurance and reinsurance contracts over the loss exposure or coverage period in proportion to the level of protection provided. In most cases, such premiums are earned ratably over the term of the contract with unearned premiums computed on a monthly or daily pro-rata basis. Premiums on retroactive property/casualty reinsurance contracts are earned at the inception of the contracts, as all underlying loss events covered by the policies occurred prior to contract inception. Premiums for life reinsurance and annuity contracts are earned when due. Premiums earned are stated net of amounts ceded to reinsurers. Premiums earned on contracts with experience-rating provisions reflect estimated loss experience under such contracts. Sales and service revenues are recognized when goods or services are transferred to a customer. A good or service is transferred when (or as) the customer obtains control of that good or service. Revenues are based on the consideration we expect to receive in connection with our promises to deliver goods and services to our customers. We manufacture and/or distribute a wide variety of industrial, building and consumer products. Our sales contracts provide customers with these products through wholesale and retail channels in exchange for consideration specified under the contracts. Contracts generally represent customer orders for individual products at stated prices. Sales contracts may contain either single or multiple performance obligations. In instances where contracts contain multiple performance obligations, we allocate the revenue to each obligation based on the relative stand-alone selling prices of each product or service. Sales revenue reflects reductions for returns, allowances, volume discounts and other incentives, some of which may be contingent on future events. In certain customer contracts, sales revenue includes certain state and local excise taxes billed to customers on specified products when those taxes are levied directly upon us by the taxing authorities. Sales revenue excludes sales taxes and value-added taxes collected on behalf of taxing authorities. Sales revenue includes consideration for shipping and other fulfillment activities performed prior to the customer obtaining control of the goods. We also elect to treat consideration for such services performed after control has passed to the customer as sales revenue. Our product sales revenues are generally recognized at a point in time when control of the product transfers to the customer, which coincides with customer pickup or product delivery or acceptance, depending on terms of the arrangement. We recognize sales revenues and related costs with respect to certain contracts over time, primarily from certain castings, forgings and aerostructures contracts. Control of the product units under these contracts transfers continuously to the customer as the product is manufactured. These products generally have no alternative use and the contract requires the customer to provide reasonable compensation if terminated for reasons other than breach of contract. Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (o) Revenue recognition (Continued) Our energy revenue derives primarily from tariff-based sales arrangements approved by various regulatory commissions. These tariff-based revenues are mainly comprised of energy, transmission, distribution and natural gas and have performance obligations to deliver energy products and services to customers which are satisfied over time as energy is delivered or services are provided. Our nonregulated energy revenue primarily relates to our renewable energy business. Energy revenues are equivalent to the amounts we have the right to invoice and correspond directly with the value to the customer of the performance to date and include billed and unbilled amounts. Payments from customers are generally due within 30 days of billing. Rates charged for energy products and services are established by regulators or contractual arrangements that establish the transaction price, as well as the allocation of price among the separate performance obligations. When preliminary regulated rates are permitted to be billed prior to final approval by the applicable regulator, certain revenue collected may be subject to refund and a liability for estimated refunds is accrued. The primary performance obligation under our freight rail transportation service contracts is to move freight from a point of origin to a point of destination. The performance obligations are represented by bills of lading which create a series of distinct services that have a similar pattern of transfer to the customer. The revenues for each performance obligation are based on various factors including the product being shipped, the origin and destination pair and contract incentives, which are outlined in various private rate agreements, common carrier public tariffs, interline foreign road agreements and pricing quotes. The transaction price is generally a per car/unit amount to transport railcars from a specified origin to a specified destination. Freight revenues are recognized over time as the service is performed because the customer simultaneously receives and consumes the benefits of the service. Revenues recognized represent the proportion of the service completed as of the balance sheet date. Invoices for freight transportation services are generally issued to customers and paid within 30 days or less. Customer incentives, which are primarily provided for shipping a specified cumulative volume or shipping to/from specific locations, are recorded as a reduction to revenue on a pro-rata basis based on actual or projected future customer shipments. Other service revenues derive from contracts with customers in which performance obligations are satisfied over time, where customers receive and consume benefits as we perform the services, or at a point in time when the services are provided. Other service revenues primarily derive from real estate brokerage, automotive repair, aircraft management, aviation training and franchising and news distribution services. Leasing revenue is generally recognized ratably over the term of the lease or based on usage, if applicable under the terms of the contract. A substantial portion of our leases are classified as operating leases. (p) Losses and loss adjustment expenses We record liabilities for unpaid losses and loss adjustment expenses under property/casualty insurance and reinsurance contracts for loss events that have occurred on or before the balance sheet date. Such liabilities represent the estimated ultimate payment amounts without discounting for time value. We base liability estimates on (1) loss reports from policyholders and cedents, (2) individual case estimates and (3) estimates of incurred but not reported losses. Losses and loss adjustment expenses in the Consolidated Statements of Earnings include paid claims, claim settlement costs and changes in estimated claim liabilities. Losses and loss adjustment expenses charged to earnings are net of amounts recovered and estimates of amounts recoverable under ceded reinsurance contracts. Reinsurance contracts do not relieve the ceding company of its obligations to indemnify policyholders with respect to the underlying insurance and reinsurance contracts. (q) Retroactive reinsurance contracts We record liabilities for unpaid losses and loss adjustment expenses under short duration retroactive reinsurance contracts consistent with other short duration property/casualty insurance and reinsurance contracts described in Note 1(p). With respect to retroactive reinsurance contracts, we also record deferred charge assets at the inception of the contracts, representing the excess, if any, of the estimated ultimate claim liabilities over the premiums earned. We subsequently amortize the deferred charge assets over the expected claim settlement periods using the interest method. Changes to the estimated timing or amount of future loss payments also produce changes in deferred charge balances. We apply changes in such estimates retrospectively and the resulting changes in deferred charge balances, together with periodic amortization, are included in insurance losses and loss adjustment expenses in the Consolidated Statements of Earnings. Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (r) Insurance policy acquisition costs We capitalize the incremental costs that directly relate to the successful sale of insurance contracts, subject to ultimate recoverability, and we subsequently amortize such costs to underwriting expenses as the related premiums are earned. Direct incremental acquisition costs include commissions, premium taxes and certain other costs associated with successful efforts. We expense all other underwriting costs as incurred. The recoverability of capitalized insurance policy acquisition costs generally reflects anticipation of investment income. The unamortized balances are included in other assets and were approximately $3.25 billion and $2.95 billion at December 31, 2020 and 2019, respectively. (s) Life and annuity insurance benefits We compute liabilities for insurance benefits under life contracts based upon estimated future investment yields, expected mortality, morbidity and lapse or withdrawal rates, as well as estimates of premiums we expect to receive and expenses we expect to incur in the future. These assumptions, as applicable, also include a margin for adverse deviation and may vary with the characteristics of the contract’s date of issuance, policy duration and country of risk. The interest rate assumptions used may vary by contract or jurisdiction. We discount periodic payment annuity liabilities based on the implicit rate as of the inception of the contracts such that the present value of the liabilities equals the premiums. Discount rates for most contracts range from 3% to 7%. (t) Regulated utilities and energy businesses Certain energy subsidiaries prepare their financial statements in accordance with authoritative guidance for regulated operations, reflecting the economic effects of regulation from the ability to recover certain costs from customers and the requirement to return revenues to customers in the future through the regulated rate-setting process. Accordingly, certain costs are deferred as regulatory assets and certain income is accrued as regulatory liabilities. Regulatory assets and liabilities will be amortized into operating expenses and revenues over various future periods. Regulatory assets and liabilities are continually assessed for probable future inclusion in regulatory rates by considering factors such as applicable regulatory or legislative changes and recent rate orders received by other regulated entities. If future inclusion in regulatory rates ceases to be probable, the amount no longer probable of inclusion in regulatory rates is charged or credited to earnings (or other comprehensive income, if applicable) or returned to customers. (u) Foreign currency The accounts of our non-U.S. based subsidiaries are measured, in most instances, using functional currencies other than the U.S. Dollar. Revenues and expenses in the financial statements of these subsidiaries are translated into U.S. Dollars at the average exchange rate for the period and assets and liabilities are translated at the exchange rate as of the end of the reporting period. The net effects

Business acquisitions

Business acquisitions	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Business acquisitions	(2) Business acquisitions Our long-held acquisition strategy is to acquire businesses that have consistent earning power, good returns on equity and able and honest management. Financial results attributable to business acquisitions are included in our Consolidated Financial Statements beginning on their respective acquisition dates. In July 2020, Berkshire Hathaway Energy (“BHE”) reached a definitive agreement with Dominion Energy, Inc. (“Dominion”) to acquire substantially all of Dominion’s natural gas transmission and storage business. On October 5, 2020, BHE and Dominion also agreed, as permitted under the acquisition agreement, to provide for the acquisition of all originally agreed upon businesses, except for certain pipeline assets (the “Excluded Assets”) and entered into a second acquisition agreement with respect to the Excluded Assets. The acquisition of the Dominion businesses, other than the Excluded Assets, was completed on November 1, 2020 and included more than 5,400 miles of natural gas transmission, gathering and storage pipelines, about 420 billion cubic feet of operated natural gas storage capacity and partial ownership of a liquefied natural gas export, import and storage facility (“Cove Point”). Under the terms of the second acquisition agreement, BHE agreed to acquire the Excluded Assets for approximately $1.3 billion in cash. The closing of this second acquisition is subject to receiving necessary regulatory approvals and other customary closing conditions and is expected to occur during the first half of 2021. The cost of the acquisition completed on November 1, 2020, was approximately $2.5 billion after post-closing adjustments as provided in the agreement. The preliminary fair values of identified assets acquired and liabilities assumed and residual goodwill are summarized as follows (in millions). Property, plant and equipment $ 9,254 Goodwill 1,732 Other 2,376 Assets acquired $ 13,362 Notes payable and other borrowings $ 5,615 Other 1,317 Liabilities assumed 6,932 Noncontrolling interests 3,916 Net assets $ 2,514 As part of this acquisition, BHE acquired an indirect 25% economic interest in Cove Point, consisting of 100% of the general partnership interest and 25% of the limited partnership interests. We concluded that Cove Point is a VIE and that we have the power to direct the activities that most significantly impact its economic performance as well as the obligation to absorb losses and receive benefits which could be significant to Cove Point. Therefore, we treat Cove Point as a consolidated subsidiary. The noncontrolling interests in the preceding table is attributable to the limited partner interests held by third parties. On October 1, 2018, we acquired MLMIC Insurance Company (“MLMIC”), a writer of medical professional liability insurance domiciled in New York. The acquisition price was approximately $2.5 billion. As of the acquisition date, the fair value of MLMIC’s assets was approximately $6.1 billion, primarily investments ($5.2 billion), and the fair value of its liabilities was approximately $3.6 billion, primarily unpaid losses and loss adjustment expenses ($3.2 billion). Notes to Consolidated Financial Statements (Continued) ( 2 ) Business acquisitions (Continued) In each of the past three years, we also completed several smaller-sized business acquisitions, which we consider as “bolt-ons” to several of our existing business operations. Aggregate consideration paid for bolt-on acquisitions, net of cash acquired was approximately $130 million in 2020, $1.7 billion in 2019 and $1.0 billion in 2018. We do not believe that these acquisitions are material, individually or in the aggregate to our Consolidated Financial Statements.

Investments in fixed maturity s

Investments in fixed maturity securities	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Investments in fixed maturity securities	(3) Investments in fixed maturity securities Investments in fixed maturity securities as of December 31, 2020 and 2019 are summarized by type below (in millions). Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2020 U.S. Treasury, U.S. government corporations and agencies $ 3,348 $ 55 $ — $ 3,403 Foreign governments 11,233 110 (5 ) 11,338 Corporate bonds 4,729 464 (2 ) 5,191 Other 414 66 (2 ) 478 $ 19,724 $ 695 $ (9 ) $ 20,410 December 31, 2019 U.S. Treasury, U.S. government corporations and agencies $ 3,054 $ 37 $ (1 ) $ 3,090 Foreign governments 8,584 63 (9 ) 8,638 Corporate bonds 5,896 459 (3 ) 6,352 Other 539 67 (1 ) 605 $ 18,073 $ 626 $ (14 ) $ 18,685 Investments in foreign governments include securities issued by national and provincial government entities as well as instruments that are unconditionally guaranteed by such entities. As of December 31, 2020, approximately 88% of our foreign government holdings were rated AA or higher by at least one of the major rating agencies. The amortized cost and estimated fair value of fixed maturity securities at December 31, 2020 are summarized below by contractual maturity dates. Amounts are in millions. Actual maturities may differ from contractual maturities due to early call or prepayment rights held by issuers. Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Mortgage-backed securities Total Amortized cost $ 10,379 $ 8,323 $ 373 $ 337 $ 312 $ 19,724 Fair value 10,448 8,456 496 640 370 20,410

Investments in equity securitie

Investments in equity securities	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Investments in equity securities	Notes to Consolidated Financial Statements (Continued) (4) Investments in equity securities Investments in equity securities as of December 31, 2020 and 2019 are summarized based on the primary industry of the investee in the table below (in millions). Cost Basis Net Unrealized Gains Fair Value December 31, 2020 * Banks, insurance and finance $ 26,312 $ 40,167 $ 66,479 Consumer products 34,747 111,583 146,330 Commercial, industrial and other 47,561 20,800 68,361 $ 108,620 $ 172,550 $ 281,170 * Approximately 68% of the aggregate fair value was concentrated in four companies (American Express Company – $18.3 billion; Apple Inc. – $120.4 billion; Bank of America Corporation – $31.3 billion and The Coca-Cola Company – $21.9 billion). Cost Basis Net Unrealized Gains Fair Value December 31, 2019 * Banks, insurance and finance $ 40,419 $ 61,976 $ 102,395 Consumer products 38,887 60,747 99,634 Commercial, industrial and other 31,034 14,964 45,998 $ 110,340 $ 137,687 $ 248,027 * Approximately 60% of the aggregate fair value was concentrated in four companies (American Express Company – $18.9 billion; Apple Inc. – $73.7 billion; Bank of America Corporation – $33.4 billion and The Coca-Cola Company – $22.1 billion). On August 8, 2019, Berkshire invested a total of $10 billion in Occidental Corporation (“Occidental”) newly issued Occidental Cumulative Perpetual Preferred Stock with an aggregate liquidation value of $10 billion and warrants to purchase up to 80 million shares of Occidental common stock at an exercise price of $62.50 per share. In accordance with the terms of the warrants, on August 3, 2020, the number of shares of common stock that can be purchased was increased to 83.86 million shares and the exercise price was reduced to $59.62 per share. The preferred stock accrues dividends at 8% per annum and is redeemable at the option of Occidental commencing in 2029 at a redemption price equal to 105% of the liquidation preference plus any accumulated and unpaid dividends, or is mandatorily redeemable under certain specified capital return events. Dividends on the preferred stock may be paid in cash or, at Occidental’s option, in shares of Occidental common stock. The warrants are exercisable in whole or in part until one year after the redemption of the preferred stock. Our investments in Occidental are included in the commercial, industrial and other category in the preceding tables.

Equity method investments

Equity method investments	12 Months Ended
	Dec. 31, 2020
Equity Method Investments And Joint Ventures [Abstract]
Equity method investments	( 5) Equity method investments Berkshire and its subsidiaries hold investments in certain businesses that are accounted for pursuant to the equity method. Currently, the most significant of these is our investment in the common stock of The Kraft Heinz Company (“Kraft Heinz”). Kraft Heinz is one of the world’s largest manufacturers and marketers of food and beverage products, including condiments and sauces, cheese and dairy, meals, meats, refreshment beverages, coffee and other grocery products. Berkshire currently owns 325,442,152 shares of Kraft Heinz common stock representing 26.6% of the outstanding shares. Notes to Consolidated Financial Statements (Continued) (5) Equity method investments (Continued) We recorded equity method earnings from our investment in Kraft Heinz of $95 million in 2020, $493 million in 2019 and losses of approximately $2.7 billion in 2018. Equity method earnings (losses) included the effects of goodwill and identifiable intangible asset impairment charges recorded by Kraft Heinz. Our share of such charges was approximately $850 million in 2020, $450 million in 2019 and $3.7 billion in 2018. We received dividends from Kraft Heinz of $521 Shares of Kraft Heinz common stock are publicly-traded and the fair value of our investment was approximately $11.3 billion at December 31, 2020 and $10.5 billion at December 31, 2019. The carrying value of our investment was approximately $13.3 billion at December 31, 2020 and $13.8 billion at December 31, 2019. As of December 31, 2020, the carrying value of our investment exceeded the fair value based on the quoted market price by $2.0 billion (15% of carrying value). In light of this fact, we evaluated our investment in Kraft Heinz for impairment. We utilize no bright-line tests in such evaluations. Based on the available facts and information regarding the operating results of Kraft Heinz, our ability and intent to hold the investment until recovery, the relative amount of the decline and the length of time that fair value was less than carrying value, we concluded that recognition of an impairment loss in earnings was not required. However, we will continue to monitor this investment and it is possible that an impairment loss will be recorded in earnings in a future period based on changes in facts and circumstances or intentions. Summarized financial information of Kraft Heinz follows (in millions). December 26, 2020 December 28, 2019 Assets $ 99,830 $ 101,450 Liabilities 49,587 49,701 Year ending December 26, 2020 Year ending December 28, 2019 Year ending December 29, 2018 Sales $ 26,185 $ 24,977 $ 26,268 Net earnings (losses) attributable to Kraft Heinz common shareholders $ 356 $ 1,935 $ (10,192 ) Other investments accounted for pursuant to the equity method include our investments in Berkadia Commercial Mortgage LLC (“Berkadia”), Pilot Travel Centers LLC (“Pilot”) and Electric Transmission Texas, LLC (“ETT”). The carrying value of our investments in these entities was approximately $4.0 billion as of December 31, 2020 and $3.7 billion as of December 31, 2019. Our equity method earnings in these entities were $631 million in 2020, $683 million in 2019 and $563 million in 2018. Additional information concerning these investments follows. We own a 50% interest in Berkadia, with Jefferies Financial Group Inc. (“Jefferies”) owning the other 50% interest. Berkadia is a servicer of commercial real estate loans in the U.S., performing primary, master and special servicing functions for U.S. government agency programs, commercial mortgage-backed securities transactions, banks, insurance companies and other financial institutions. A source of funding for Berkadia’s operations is through its issuance of commercial paper, which is currently limited to $1.5 billion. On December 31, 2020, Berkadia’s commercial paper outstanding was $1.47 billion. The commercial paper is supported by a surety policy issued by a Berkshire insurance subsidiary. Jefferies is obligated to indemnify us for one-half of any losses incurred under the policy. A Berkshire Hathaway Energy Company subsidiary owns a 50% interest in ETT, an owner and operator of electric transmission assets in the Electric Reliability Council of Texas footprint. American Electric Power owns the other 50% interest. On October 3, 2017, we entered into an investment agreement and an equity purchase agreement whereby we acquired a 38.6% interest in Pilot, headquartered in Knoxville, Tennessee. Pilot is the largest operator of travel centers in North America, supplying more than 11 billion gallons of fuel per year via more than 950 retail locations across 44 U.S. states and six Canadian provinces and through wholesale distribution. The Haslam family currently owns a 50.1% interest in Pilot and a third party owns the remaining 11.3% interest. We also entered into an agreement to acquire in 2023 an additional 41.4% interest in Pilot with the Haslam family retaining a 20% interest. As a result, Berkshire will become the majority owner of Pilot in 2023.

Investment gains_losses

Investment gains/losses	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Investment gains/losses	Notes to Consolidated Financial Statements (Continued) (6) Investment gains/losses Investment gains/losses for each of the three years ending December 31, 2020 are summarized below (in millions). 2020 2019 2018 Equity securities: Change in unrealized investment gains/losses during the year on securities held at the end of the period $ 54,951 $ 69,581 $ (22,729 ) Investment gains/losses during the year on securities sold (14,036 ) 1,585 291 40,915 71,166 (22,438 ) Fixed maturity securities: Gross realized gains 56 87 480 Gross realized losses (27 ) (25 ) (227 ) Other (39 ) (105 ) 30 $ 40,905 $ 71,123 $ (22,155 ) Equity securities gains and losses include unrealized gains and losses from changes in fair values during the period on equity securities we still own, as well as gains and losses on securities we sold during the period. As reflected in the Consolidated Statements of Cash Flows, we received proceeds of approximately $38.8 billion in 2020, $14.3 billion in 2019 and $18.8 billion in 2018 from sales of equity securities. In the preceding table, investment gains/losses on equity securities sold reflect the difference between proceeds from sales and the fair value of the equity security sold at the beginning of the period or the purchase date, if later. Our taxable gains on equity securities sold during the year, which are generally the difference between the proceeds from sales and our original cost, were $6.2 billion in 2020, $3.2 billion in 2019 and $3.3 billion in 2018.

Loans and finance receivables

Loans and finance receivables	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Loans and finance receivables	(7) Loans and finance receivables Loans and finance receivables are summarized as follows (in millions). December 31, 2020 2019 Loans and finance receivables before allowances and discounts $ 20,436 $ 18,199 Allowances for uncollectible loans (712 ) (167 ) Unamortized acquisition discounts and points (523 ) (505 ) $ 19,201 $ 17,527 Loans and finance receivables are principally manufactured home loans, and to a lesser extent, commercial loans and site-built home loans. Reconciliations of the allowance for credit losses on loans and finance receivables for 2020 and 2019 follow (in millions). 2020 2019 Balance at beginning of year $ 167 $ 177 Adoption of ASC 326 486 — Provision for credit losses 177 125 Charge-offs, net of recoveries (118 ) (135 ) Balance at December 31 $ 712 $ 167 At December 31, 2020, approximately 99% of home loan balances were evaluated collectively for impairment. At December 31, 2020, we considered approximately 97% of the loan balances to be current as to payment status. A summary of performing and non-performing home loans before discounts and allowances by year of loan origination as of December 31, 2020 follows (in millions). Loans and Financing Receivables by Origination Year 2020 2019 2018 2017 2016 Prior Total Performing $ 4,430 $ 2,537 $ 1,928 $ 1,424 $ 1,276 $ 6,645 $ 18,240 Non-performing 3 5 7 7 7 43 72 Total $ 4,433 $ 2,542 $ 1,935 $ 1,431 $ 1,283 $ 6,688 $ 18,312 Notes to Consolidated Financial Statements (Continued) (7) Loans and finance receivables (Continued) We are party to an agreement with Seritage Growth Properties to provide a $2.0 billion term loan facility, which expires on July 31, 2023. The outstanding loan under the facility was approximately $1.6 billion at December 31, 2020 and 2019, and is secured by mortgages on real estate properties. In 2020, we provided a loan to Lee Enterprises, Inc. in connection with its acquisition of our newspaper operations and the repayment by Lee of its then outstanding credit facilities. The loan balance as of December 31, 2020 was $524 million. We are the sole lender to each of these entities and each of these loans is current as to payment status.

Other receivables

Other receivables	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Other receivables	(8) Other receivables Other receivables of insurance and other businesses are comprised of the following (in millions). December 31, 2020 2019 Insurance premiums receivable $ 14,025 $ 13,379 Reinsurance recoverables 4,805 4,470 Trade receivables 11,521 12,275 Other 2,637 2,712 Allowances for uncollectible accounts (678 ) (418 ) $ 32,310 $ 32,418 Receivables of our railroad and utilities and energy businesses are comprised of the following (in millions). December 31, 2020 2019 Trade receivables $ 3,235 $ 3,120 Other 438 388 Allowances for uncollectible accounts (131 ) (91 ) $ 3,542 $ 3,417 Provisions for credit losses on receivables in the preceding tables were $564 million in 2020 and $363 million in 2019. Net charge-offs were $401 million in 2020 and $350 million in 2019.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Inventories	(9) Inventories Inventories are comprised of the following (in millions). December 31, 2020 2019 Raw materials $ 4,821 $ 4,492 Work in process and other 2,541 2,700 Finished manufactured goods 4,412 4,821 Goods acquired for resale 7,434 7,839 $ 19,208 $ 19,852

Property, plant and equipment i

Property, plant and equipment including equipment held for lease	12 Months Ended
	Dec. 31, 2020
Property, plant and equipment including equipment held for lease	(10) Property, plant and equipment A summary of property, plant and equipment of our insurance and other businesses follows (in millions). December 31, 2020 2019 Land, buildings and improvements $ 13,799 $ 13,259 Machinery and equipment 25,488 24,285 Furniture, fixtures and other 4,530 4,666 43,817 42,210 Accumulated depreciation (22,617 ) (20,772 ) $ 21,200 $ 21,438 Notes to Consolidated Financial Statements (Continued) (10) Property, plant and equipment (Continued) A summary of property, plant and equipment of railroad and utilities and energy businesses follows (in millions). The utility generation, transmission and distribution systems and interstate natural gas pipeline assets are owned by regulated public utility and natural gas pipeline subsidiaries. December 31, 2020 2019 Railroad: Land, track structure and other roadway $ 63,824 $ 62,404 Locomotives, freight cars and other equipment 13,523 13,482 Construction in progress 916 748 78,263 76,634 Accumulated depreciation (13,175 ) (12,101 ) 65,088 64,533 Utilities and energy: Utility generation, transmission and distribution systems 86,730 81,127 Interstate natural gas pipeline assets 16,667 8,165 Independent power plants and other assets 12,671 8,817 Construction in progress 3,308 3,732 119,376 101,841 Accumulated depreciation (33,248 ) (28,536 ) 86,128 73,305 $ 151,216 $ 137,838 Depreciation expense for each of the three years ending December 31, 2020 is summarized below (in millions). 2020 2019 2018 Insurance and other $ 2,320 $ 2,269 $ 2,186 Railroad, utilities and energy 5,799 5,297 5,098 $ 8,119 $ 7,566 $ 7,284
Equipment held for lease [Member]
Property, plant and equipment including equipment held for lease	(11) Equipment held for lease Equipment held for lease includes railcars, aircraft, over-the-road trailers, intermodal tank containers, cranes, storage units and furniture. Equipment held for lease is summarized below (in millions). December 31, 2020 2019 Railcars $ 9,402 $ 9,260 Aircraft 8,204 8,093 Other 4,868 4,862 22,474 22,215 Accumulated depreciation (7,873 ) (7,150 ) $ 14,601 $ 15,065 Depreciation expense for equipment held for lease was $1,200 million in 2020, $1,181 million in 2019 and $1,102 million in 2018. Fixed and variable operating lease revenues for each of the two years ending December 31, 2020 are summarized below (in millions). 2020 2019 Fixed lease revenue $ 4,262 $ 4,415 Variable lease revenue 947 1,441 $ 5,209 $ 5,856 Notes to Consolidated Financial Statements (Continued) (11) Equipment held for lease (Continued) A summary of future operating lease receipts as of December 31, 2020 follows (in millions). 2021 2022 2023 2024 2025 Thereafter Total $ 2,618 $ 1,962 $ 1,429 $ 905 $ 443 $ 387 $ 7,744

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	(12) Leases We are party to contracts where we lease property from others. As a lessee, we primarily lease office and operating facilities, locomotives, freight cars, energy generation facilities and transmission assets. Operating lease right-of-use assets were $5,579 million and lease liabilities were $5,469 million at December 31, 2020. Operating lease right-of-use assets were $5,941 million and lease liabilities were $5,882 million at December 31, 2019. Such amounts were included in other assets and accounts payable, accruals and other liabilities in our Consolidated Balance Sheet. The weighted average term of these leases was approximately 7.3 years at December 31, 2020 and 7.7 years at December 31, 2019. The weighted average discount rate used to measure lease liabilities was approximately 3.6% at December 31, 2020 and 3.8% at December 31, 2019. A summary of our remaining operating lease payments as of December 31, 2020 and December 31, 2019 follows (in millions). Year 1 Year 2 Year 3 Year 4 Year 5 Thereafter Total lease payments Amount representing interest Lease liabilities December 31: 2020 $ 1,342 $ 1,111 $ 905 $ 725 $ 544 $ 1,691 $ 6,318 $ (849 ) $ 5,469 2019 1,374 1,183 950 764 620 1,988 6,879 (997 ) 5,882 Components of operating lease costs for the years ending December 31, 2020 and 2019, by type, are summarized in the following table (in millions). 2020 2019 Operating lease cost $ 1,413 $ 1,459 Short-term lease cost 145 178 Variable lease cost 228 276 Sublease income (10 ) (24 ) Total lease cost $ 1,776 $ 1,889

Goodwill and other intangible a

Goodwill and other intangible assets	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and other intangible assets	(13) Goodwill Reconciliations of the changes in the carrying value of goodwill during 2020 and 2019 follows (in millions). December 31, 2020 2019 Balance at beginning of year $ 81,882 $ 81,025 Acquisitions of businesses 1,758 890 Impairment charges (10,033 ) (90 ) Other, including foreign currency translation 127 57 Balance at end of year* $ 73,734 $ 81,882 * Net of accumulated goodwill impairments of $11.0 billion as of December 31, 2020 and $1.1 billion as of December 31, 2019. Notes to Consolidated Financial Statements (Continued) (13) Goodwill and other intangible assets (Continued) The gross carrying amounts and related accumulated amortization of other intangible assets are summarized as follows (in millions). December 31, 2020 December 31, 2019 Gross carrying amount Accumulated amortization Gross carrying amount Accumulated amortization Insurance and other: Customer relationships $ 27,374 $ 5,756 $ 27,943 $ 5,025 Trademarks and trade names 5,206 779 5,286 759 Patents and technology 4,766 3,313 4,560 3,032 Other 3,339 1,375 3,364 1,286 $ 40,685 $ 11,223 $ 41,153 $ 10,102 Railroad, utilities and energy: Customer relationships $ 678 $ 361 $ 678 $ 324 Trademarks, trade names and other 1,003 98 325 84 $ 1,681 $ 459 $ 1,003 $ 408 Intangible asset amortization expense was $1,277 million in 2020, $1,317 million in 2019 and $1,393 million in 2018. Estimated amortization expense over the next five years is as follows (in millions): 2021 – $1,262; 2022 – $1,190; 2023 – $1,108; 2024 – $986 and 2025 – $906. Intangible assets with indefinite lives were $18.3 billion as of December 31, 2020 and $19.0 billion as of December 31, 2019 and primarily related to certain customer relationships and trademarks and trade names. During 2020, we concluded it was necessary to reevaluate goodwill and indefinite-lived intangible assets of certain of our reporting units for impairment due to the disruptions arising from the COVID-19 pandemic. We believed that the most significant of these disruptions related to the air travel and commercial aerospace and supporting industries. We recorded pre-tax goodwill impairment charges of approximately $10 billion and pre-tax indefinite-lived intangible asset impairment charges of $638 million in the second quarter of 2020. Approximately $10 billion of these charges related to Precision Castparts Corp. (“PCC”), the largest business within Berkshire's manufacturing segment. The carrying value of PCC-related goodwill and indefinite-lived intangible assets prior to the impairment charges was approximately $31 billion. The impairment charges were determined based on discounted cash flow methods and reflected our assessments of the risks and uncertainties associated with the aerospace industry. Significant judgment is required in estimating the fair value of a reporting unit and in performing impairment tests. Due to the inherent uncertainty in forecasting cash flows and earnings, actual results in the future may vary significantly from the forecasts.

Derivative contracts

Derivative contracts	12 Months Ended
	Dec. 31, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative contracts	(14) Derivative We are party to derivative contracts through certain of our subsidiaries. The most significant derivative contracts consist of equity index put option contracts. Information related to these contracts follows (dollars in millions). December 31, 2020 2019 Balance sheet liabilities - at fair value $ 1,065 $ 968 Notional value 10,991 14,385 Intrinsic value 727 397 Weighted average remaining life (in years) 1.2 1.8 The equity index put option contracts are European style options written prior to March 2008 on four major equity indexes. Notional value in the preceding table represents the aggregate undiscounted amounts payable assuming that the value of each index is zero at each contract’s expiration date. Intrinsic value is the undiscounted liability assuming the contracts are settled based on the index values and foreign currency exchange rates as of the balance sheet date. Substantially all open contracts as of December 31, 2020 will expire by February 2023. Notes to Consolidated Financial Statements (Continued) (14) Derivative contracts (Continued) Future payments, if any, under any given contract will be required if the prevailing index value is below the contract strike price at the expiration date. We received aggregate premiums of $1.9 billion on the contract inception dates with respect to unexpired contracts as of December 31, 2020 and we have no counterparty credit risk. We recorded derivative contract losses of $159 million in 2020, gains of $1,484 million in 2019 and losses of $300 million in 2018, with respect to our equity index put option contracts. These gains and losses were primarily due to changes in the equity index values. These contracts may not be unilaterally terminated or fully settled before the expiration dates and the ultimate amount of cash basis gains or losses on these contracts will not be determined until the contract expiration dates. Our regulated utility subsidiaries may use forward purchases and sales, futures, swaps and options to manage a portion of their commodity price risks. Most of these net derivative contract assets or liabilities of our regulated utilities are probable of recovery through rates and are offset by regulatory liabilities or assets.

Unpaid losses and loss adjustme

Unpaid losses and loss adjustment expenses	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Unpaid losses and loss adjustment expenses	(1 5 ) Unpaid losses and loss adjustment expenses Our liabilities for unpaid losses and loss adjustment expenses (also referred to as “claim liabilities”) under property and casualty insurance and reinsurance contracts are based upon estimates of the ultimate claim costs associated with claim occurrences as of the balance sheet date and include estimates for incurred-but-not-reported (“IBNR”) claims. A reconciliation of the changes in claim liabilities, excluding liabilities under retroactive reinsurance contracts (see Note 16), for each of the three years ending December 31, 2020 is as follows (in millions). 2020 2019 2018 Balances at beginning of year: Gross liabilities $ 73,019 $ 68,458 $ 61,122 Reinsurance recoverable on unpaid losses (2,855 ) (3,060 ) (3,201 ) Net liabilities 70,164 65,398 57,921 Incurred losses and loss adjustment expenses: Current accident year events 43,400 43,335 39,876 Prior accident years’ events (356 ) (752 ) (1,406 ) Total 43,044 42,583 38,470 Paid losses and loss adjustment expenses: Current accident year events (17,884 ) (19,482 ) (18,391 ) Prior accident years’ events (18,862 ) (17,642 ) (15,452 ) Total (36,746 ) (37,124 ) (33,843 ) Foreign currency translation adjustment 480 (23 ) (331 ) Business acquisition (disposition) — (670 ) 3,181 Balances at December 31: Net liabilities 76,942 70,164 65,398 Reinsurance recoverable on unpaid losses 2,912 2,855 3,060 Gross liabilities $ 79,854 $ 73,019 $ 68,458 Incurred losses and loss adjustment expenses shown in the preceding table were recorded in earnings and related to insured events occurring in the current year (“current accident year”) and events occurring in all prior years (“prior accident years”). Current accident year losses included approximately $950 million in 2020, $1.0 billion in 2019 and $1.6 billion in 2018 from significant catastrophe events occurring in each year. Current accident year losses in 2020 also reflected the effects of low private passenger automobile claims frequencies and increased loss commercial insurance and reinsurance business attributable to the COVID-19 pandemic. We recorded net reductions of estimated ultimate liabilities for prior accident years of $356 million in 2020, $752 million in 2019 and $1,406 million in 2018, which produced corresponding reductions in incurred losses and loss adjustment expenses. These reductions, as percentages of the net liabilities at the beginning of each year, were 0.5% in 2020, 1.1% in 2019 and 2.4% in 2018. Notes to Consolidated Financial Statements (Continued) (1 5 ) Unpaid losses and loss adjustment expenses (Continued) Estimated ultimate liabilities for prior years’ loss events related to primary insurance were reduced by $518 million in 2020, $457 million in 2019 and $937 million in 2018. The decrease in 2020 was primarily attributable to reductions for private passenger automobile, medical professional liability and workers’ compensation claims, partly offset by increases for other casualty claims. The decrease in 2019 reflected reductions in medical professional liability and workers’ compensation claims, partially offset by higher commercial auto and other liability claims. The decrease in 2018 was primarily due to reductions for workers’ compensation, medical professional liability and private passenger automobile claims. Estimated ultimate liabilities for prior years’ loss events related to property and casualty reinsurance increased $162 million in 2020 and were reduced $295 million in 2019 and $469 million in 2018. The increase in 2020 included increased claims estimates for legacy casualty exposures. Estimated claim liabilities included amounts for environmental, asbestos and other latent injury exposures, net of reinsurance recoverable, of approximately $2.1 billion at December 31, 2020 and $1.7 billion at December 31, 2019. These liabilities are subject to change due to changes in the legal and regulatory environment. We are unable to reliably estimate additional losses or a range of losses that are reasonably possible for these claims. Disaggregated information concerning our claims liabilities is provided below and in the pages that follow. The effects of businesses acquired or disposed during the period are reflected in the data presented on a retrospective basis. A reconciliation of the disaggregated net unpaid losses and allocated loss adjustment expenses (the latter referred to as “ALAE”) of GEICO, Berkshire Hathaway Primary Group (“BH Primary”) and Berkshire Hathaway Reinsurance Group (“BHRG”) to our consolidated unpaid losses and loss adjustment expenses as of December 31, 2020 follows (in millions). GEICO Physical Damage GEICO Auto Liability BH Primary Medical Professional Liability BH Primary Workers’ Compensation and Other Casualty BHRG Property BHRG Casualty Total Unpaid losses and ALAE, net $ 524 $ 18,755 $ 7,897 $ 11,294 $ 11,280 $ 22,890 $ 72,640 Reinsurance recoverable — 1,109 49 621 181 864 2,824 Unpaid unallocated loss adjustment expenses 2,671 Other unpaid losses and loss adjustment expenses 1,719 Unpaid losses and loss adjustment expenses $ 79,854 GEICO GEICO’s claim liabilities predominantly relate to various types of private passenger auto liability and physical damage claims. For such claims, we establish and evaluate unpaid claim liabilities using standard actuarial loss development methods and techniques. The actuarial methods utilize historical claims data, adjusted when deemed appropriate to reflect perceived changes in loss patterns. Claim liabilities include average, case, case development and IBNR estimates. We establish average liabilities based on expected severities for newly reported physical damage and liability claims prior to establishing individual case reserves when insufficient time or information is available for specific claim estimates and for large volumes of minor physical damage claims that once reported are quickly settled. We establish case loss estimates for liability claims, including estimates for loss adjustment expenses, as the facts and merits of the claim are evaluated. Estimates for liability coverages are more uncertain than for physical damage coverages, primarily due to the longer claim-tails, the greater chance of protracted litigation and the incompleteness of facts at the time the case estimate is first established. The “claim-tail” is the time period between the claim occurrence date and settlement date. Consequently, we establish additional case development liabilities, which are usually percentages of the case liabilities. For unreported claims, IBNR liabilities are estimated by projecting the ultimate number of claims expected (reported and unreported) for each significant coverage and deducting reported claims to produce estimated unreported claims. The product of the average cost per unreported claim and the number of unreported claims produces the IBNR liability estimate. We may record supplemental IBNR liabilities in certain situations when actuarial techniques are difficult to apply. Notes to Consolidated Financial Statements (Continued) (1 5 ) Unpaid losses and loss adjustment expenses (Continued) GEICO’s incurred and paid losses and ALAE, net of reinsurance, are summarized by accident year below for physical damage and auto liability claims. IBNR and case development liabilities are as of December 31, 2020. Claim counts are established when accidents that may result in a liability are reported and are based on policy coverage. Each claim event may generate claims under multiple coverages, and thus may result in multiple counts. The “Cumulative Number of Reported Claims” includes the combined number of reported claims for all policy coverages and excludes projected IBNR claims. Dollars are in millions. Physical Damage Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2019 $ 9,020 $ 8,920 $ 69 8,929 2020 8,603 296 7,794 Incurred losses and ALAE $ 17,523 Cumulative Paid Losses and ALAE through December 31, Accident Year 2019* 2020 2019 $ 8,678 $ 8,905 2020 8,118 Paid losses and ALAE 17,023 Net unpaid losses and ALAE for 2019 – 2020 accident years 500 Net unpaid losses and ALAE for accident years before 2019 24 Net unpaid losses and ALAE $ 524 Auto Liability Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2016 $ 11,800 $ 12,184 $ 12,149 $ 12,178 $ 12,198 $ 222 2,451 2017 14,095 13,864 13,888 13,824 502 2,639 2018 15,383 15,226 14,985 1,163 2,702 2019 16,901 16,678 2,905 2,749 2020 14,637 4,482 1,945 Incurred losses and ALAE $ 72,322 Cumulative Paid Losses and ALAE through December 31, Accident Year 2016* 2017* 2018* 2019* 2020 2016 $ 5,069 $ 8,716 $ 10,330 $ 11,294 $ 11,718 2017 5,806 9,944 11,799 12,729 2018 6,218 10,772 12,658 2019 6,742 11,671 2020 5,395 Paid losses and ALAE 54,171 Net unpaid losses and ALAE for 2016 – 2020 accident years 18,151 Net unpaid losses and ALAE for accident years before 2016 604 Net unpaid losses and ALAE $ 18,755 * Unaudited required supplemental information Notes to Consolidated Financial Statements (Continued) (1 5 ) Unpaid losses and loss adjustment expenses (Continued) BH Primary BH Primary’s liabilities for unpaid losses and loss adjustment expenses primarily derive from medical professional liability and workers’ compensation and other casualty insurance, including commercial auto and general liability insurance. Incurred and paid losses and ALAE are summarized by accident year in the following tables, disaggregated by medical professional liability coverages and workers’ compensation and other casualty coverages. IBNR and case development liabilities are as of December 31, 2020. The cumulative number of reported claims reflects the number of individual claimants and includes claims that ultimately resulted in no liability or payment. Dollars are in millions. BH Primary Medical Professional Liability We estimate the ultimate expected incurred losses and loss adjustment expenses for medical professional claim liabilities using a variety of commonly accepted actuarial methodologies, such as the paid and incurred development method and Bornhuetter-Ferguson based methods, as well as other techniques that consider insured loss exposures and historical and expected loss trends, among other factors. These methodologies produce loss estimates from which we determine our best estimate. In addition, we study developments in older accident years and adjust initial loss estimates to reflect recent development based upon claim age, coverage and litigation experience. Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2011 $ 1,346 $ 1,334 $ 1,321 $ 1,262 $ 1,173 $ 1,115 $ 1,050 $ 1,004 $ 968 $ 972 $ 39 11 2012 1,336 1,306 1,277 1,223 1,168 1,078 1,035 998 988 53 11 2013 1,328 1,296 1,261 1,195 1,127 1,086 1,019 985 65 11 2014 1,370 1,375 1,305 1,246 1,218 1,127 1,061 129 11 2015 1,374 1,342 1,269 1,290 1,218 1,157 202 12 2016 1,392 1,416 1,414 1,394 1,341 286 14 2017 1,466 1,499 1,495 1,474 494 20 2018 1,602 1,650 1,659 780 22 2019 1,670 1,691 1,204 17 2020 1,704 1,529 13 Incurred losses and ALAE $ 13,032 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 16 $ 82 $ 200 $ 356 $ 517 $ 632 $ 711 $ 767 $ 822 $ 842 2012 15 93 218 377 522 642 725 789 830 2013 15 90 219 368 518 635 743 793 2014 21 106 238 396 540 671 752 2015 23 108 218 382 543 663 2016 22 115 274 461 620 2017 27 128 300 457 2018 35 166 367 2019 39 160 2020 34 Paid losses and ALAE 5,518 Net unpaid losses and ALAE for 2011– 2020 accident years 7,514 Net unpaid losses and ALAE for accident years before 2011 383 Net unpaid losses and ALAE $ 7,897 * Unaudited required supplemental information Notes to Consolidated Financial Statements (Continued) (1 5 ) Unpaid losses and loss adjustment expenses (Continued) BH Primary Workers’ Compensation and Other Casualty We periodically evaluate ultimate loss and loss adjustment expense estimates for the workers’ compensation and other casualty claims using a combination of commonly accepted actuarial methodologies such as the Bornhuetter-Ferguson and chain-ladder approaches using paid and incurred loss data. Paid and incurred loss data is segregated and analyzed by state due to the different state regulatory frameworks that may impact certain factors, including the duration and amount of loss payments. We also separately study the various components of liabilities, such as employee lost wages, medical expenses and the costs of claims investigations and administration. We establish case liabilities for reported claims based upon the facts and circumstances of the claim. The excess of the ultimate projected losses, including the expected development of case estimates, and the case-basis liabilities is included in IBNR liabilities. Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2011 $ 738 $ 675 $ 675 $ 624 $ 621 $ 618 $ 607 $ 596 $ 591 $ 576 $ 39 46 2012 873 850 837 791 780 762 750 736 718 53 53 2013 1,258 1,228 1,178 1,127 1,096 1,072 1,050 1,028 120 67 2014 1,743 1,638 1,614 1,548 1,482 1,497 1,477 190 90 2015 2,169 2,127 2,042 2,014 2,025 1,997 267 111 2016 2,511 2,422 2,359 2,325 2,365 470 115 2017 3,044 2,907 2,842 2,843 691 138 2018 3,544 3,412 3,480 1,152 160 2019 4,074 4,102 1,788 170 2020 4,421 2,987 120 Incurred losses and ALAE $ 23,007 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 109 $ 220 $ 333 $ 403 $ 453 $ 481 $ 496 $ 505 $ 512 $ 519 2012 116 299 414 501 560 592 611 626 634 2013 177 422 609 725 793 835 858 874 2014 239 557 800 1,007 1,111 1,176 1,214 2015 289 700 1,017 1,289 1,488 1,570 2016 329 775 1,148 1,461 1,661 2017 441 1,003 1,434 1,771 2018 538 1,198 1,683 2019 682 1,478 2020 695 Paid losses and ALAE 12,099 Net unpaid losses and ALAE for 2011 – 2020 accident years 10,908 Net unpaid losses and ALAE for accident years before 2011 386 Net unpaid losses and ALAE $ 11,294 * Unaudited required supplemental information BHRG We use a variety of methodologies to establish BHRG’s estimates for property and casualty claims liabilities. We use certain methodologies, such as paid and incurred loss development techniques, incurred and paid loss Bornhuetter-Ferguson techniques and frequency and severity techniques, as well as ground-up techniques when appropriate. Our claims liabilities are principally a function of reported losses from ceding companies, case development and IBNR liability estimates. Case loss estimates are reported under our contracts either individually or in bulk as provided under the terms of the contracts. We may independently evaluate case losses reported by the ceding company, and if deemed appropriate, we may establish case liabilities based on our estimates. Notes to Consolidated Financial Statements (Continued) (1 5 ) Unpaid losses and loss adjustment expenses (Continued) Estimated IBNR liabilities are affected by expected case loss emergence patterns and expected loss ratios, which are evaluated as groups of contracts with similar exposures or on a contract-by-contract basis. Estimated case and IBNR liabilities for major catastrophe events are generally based on a per-contract assessment of the ultimate cost associated with the individual loss event. Claim count data is not provided consistently by ceding companies under our contracts or is otherwise considered unreliable. Incurred and paid losses and ALAE of BHRG are disaggregated based on losses that are expected to have shorter claim-tails (property) and losses expected to have longer claim-tails (casualty). Under certain contracts, the coverage can apply to multiple lines of business written by the ceding company, whether property, casualty or combined, and the ceding company may not report loss data by such lines consistently, if at all. In those instances, we allocated losses to property and casualty coverages based on internal estimates. BHRG’s disaggregated incurred and paid losses and ALAE are summarized by accident year, net of reinsurance. IBNR and case development liabilities are as of December 31, 2020. Dollars are in millions. BHRG Property Incurred Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities 2011 $ 4,111 $ 4,095 $ 3,804 $ 3,711 $ 3,707 $ 3,672 $ 3,654 $ 3,638 $ 3,627 $ 3,616 $ 30 2012 3,153 2,846 2,644 2,403 2,351 2,348 2,329 2,315 2,305 35 2013 3,255 3,093 2,745 2,653 2,631 2,570 2,518 2,504 45 2014 2,648 2,436 2,322 2,178 2,123 2,050 2,021 48 2015 3,287 3,135 2,577 2,979 2,976 3,000 143 2016 3,293 3,923 3,646 3,614 3,616 218 2017 5,291 4,986 4,837 4,727 187 2018 4,426 4,524 4,397 678 2019 4,146 4,299 952 2020 5,858 3,129 Incurred losses and ALAE $ 36,343 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 609 $ 2,259 $ 2,917 $ 3,188 $ 3,304 $ 3,387 $ 3,429 $ 3,474 $ 3,493 $ 3,507 2012 262 1,232 1,813 1,950 2,040 2,117 2,135 2,181 2,199 2013 526 1,459 1,906 2,105 2,226 2,307 2,347 2,376 2014 467 1,249 1,574 1,713 1,779 1,829 1,858 2015 581 1,614 1,969 2,166 2,271 2,453 2016 709 1,811 2,208 2,670 2,923 2017 1,028 2,734 3,660 3,972 2018 915 2,341 2,868 2019 751 2,282 2020 960 Paid losses and ALAE 25,398 Net unpaid losses and ALAE for 2011 – 2020 accident years 10,945 Net unpaid losses and ALAE for accident years before 2011 335 Net unpaid losses and ALAE $ 11,280 * Unaudited required supplemental information Notes to Consolidated Financial Statements (Continued) (1 5 ) Unpaid losses and loss adjustment expenses (Continued) BHRG Casualty Incurred Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities 2011 $ 2,635 $ 2,726 $ 2,595 $ 2,536 $ 2,447 $ 2,354 $ 2,346 $ 2,307 $ 2,272 $ 2,255 $ 279 2012 2,820 3,002 2,837 2,899 2,827 2,712 2,645 2,588 2,581 317 2013 2,160 2,298 2,328 2,170 2,114 2,060 1,964 1,892 387 2014 1,900 2,099 2,068 2,030 1,944 1,980 1,970 537 2015 1,902 2,109 2,137 2,035 1,908 1,870 455 2016 1,928 2,138 2,047 2,003 1,922 555 2017 2,216 2,711 2,588 2,494 762 2018 2,948 3,585 3,509 1,183 2019 3,455 3,931 1,924 2020 3,883 2,754 Incurred losses and ALAE $ 26,307 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 294 $ 824 $ 1,169 $ 1,412 $ 1,501 $ 1,595 $ 1,673 $ 1,713 $ 1,748 $ 1,776 2012 312 757 1,150 1,381 1,539 1,664 1,764 1,825 1,883 2013 294 530 818 947 1,052 1,155 1,215 1,273 2014 153 488 655 765 889 974 1,119 2015 199 500 725 846 938 1,029 2016 255 563 742 874 972 2017 233 574 830 1,282 2018 267 875 1,649 2019 356 906 2020 406 Paid losses and ALAE 12,295 Net unpaid losses and ALAE for 2011 – 2020 accident years 14,012 Net unpaid losses and ALAE for accident years before 2011 8,878 Net unpaid losses and ALAE $ 22,890 * Unaudited required supplemental information Notes to Consolidated Financial Statements (Continued) (1 5 ) Unpaid losses and loss adjustment expenses (Continued) Required supplemental unaudited average historical claims duration information based on the net losses and ALAE incurred and paid accident year data in the preceding tables follows. The percentages show the average portions of net losses and ALAE paid by each succeeding year, with year 1 representing the current accident year. Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance In Year 1 2 3 4 5 6 7 8 9 10 GEICO Physical Damage 97 % 2 % GEICO Auto Liability 42 % 29 % 13 % 7 % 4 % BH Primary Medical Professional Liability 2 % 7 % 12 % 14 % 14 % 12 % 9 % 6 % 5 % 2 % BH Primary Workers’ Compensation and Other Casualty 16 % 21 % 16 % 13 % 8 % 4 % 3 % 2 % 1 % 1 % BHRG Property 19 % 37 % 17 % 8 % 4 % 4 % 1 % 2 % 1 % 0 % BHRG Casualty 11 % 16 % 14 % 9 % 5 % 5 % 5 % 2 % 2 % 1 %

Retroactive reinsurance contrac

Retroactive reinsurance contracts	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Retroactive reinsurance contracts	(1 6 ) Retroactive Retroactive reinsurance policies provide indemnification of losses and loss adjustment expenses of short-duration insurance contracts with respect to underlying loss events that occurred prior to the contract inception date. Claims payments may commence immediately after the contract date or, when applicable, once a contractual retention amount has been reached. Reconciliations of the changes in estimated liabilities for retroactive reinsurance unpaid losses and loss adjustment expenses (“claim liabilities”) and related deferred charge reinsurance assumed assets for each of the three years ended December 31, 2020 follow (in millions). 2020 2019 2018 Unpaid losses and loss adjustment expenses Deferred charges reinsurance assumed Unpaid losses and loss adjustment expenses Deferred charges reinsurance assumed Unpaid losses and loss adjustment expenses Deferred charges reinsurance assumed Balances at beginning of year $ 42,441 $ (13,747 ) $ 41,834 $ (14,104 ) $ 42,937 $ (15,278 ) Incurred losses and loss adjustment expenses: Current year contracts — — 1,138 (453 ) 603 (86 ) Prior years’ contracts (399 ) 1,306 378 810 (341 ) 1,260 Total (399 ) 1,306 1,516 357 262 1,174 Paid losses and loss adjustment expenses (1,076 ) — (909 ) — (1,365 ) — Balances at December 31 $ 40,966 $ (12,441 ) $ 42,441 $ (13,747 ) $ 41,834 $ (14,104 ) Incurred losses and loss adjustment expenses, net of deferred charges $ 907 $ 1,873 $ 1,436 In the preceding table, classifications of incurred losses and loss adjustment expenses are based on the inception dates of the contracts. We do not believe that analysis of losses incurred and paid by accident year of the underlying event is relevant or meaningful given that our exposure to losses incepts when the contract incepts. Further, we believe the classifications of reported claims and case development liabilities have little or no practical analytical value. Estimated ultimate claim liabilities included $17.7 billion at December 31, 2020 and $18.2 billion at December 31, 2019, with respect to an agreement with various subsidiaries of American International Group, Inc. (collectively, “AIG”) to indemnify AIG for 80% of up to $25 billion of losses and allocated loss adjustment expenses in excess of $25 billion retained by AIG for certain commercial insurance loss events occurring prior to 2016. The related deferred charge assets were $5.4 billion at December 31, 2020 and $6.3 billion at December 31, 2019. Notes to Consolidated Financial Statements (Continued) (1 6 ) Retroactive (Continued) Incurred losses and loss adjustment expenses related to contracts written in prior years were $907 million in 2020, $1,188 million in 2019 and $919 million in 2018, which included recurring amortization of deferred charges and the effect of changes in the timing and amount of expected future loss payments. In establishing retroactive reinsurance claim liabilities, we analyze historical aggregate loss payment patterns and project losses into the future under various probability-weighted scenarios. We expect the claim-tail to be very long for many contracts, with some lasting several decades. We monitor claim payment activity and review ceding company reports and other information concerning the underlying losses. We reassess and revise the expected timing and amounts of ultimate losses periodically or when significant events are revealed through our monitoring and review processes. Our retroactive reinsurance claim liabilities include estimated liabilities for environmental, asbestos and other latent injury exposures of approximately $12.5 billion at December 31, 2020 and $12.9 billion at December 31, 2019. Retroactive reinsurance contracts are generally subject to aggregate policy limits and thus, our exposure to such claims under these contracts is likewise limited. We monitor evolving case law and its effect on environmental and other latent injury claims. Changing laws or government regulations, newly identified toxins, newly reported claims, new theories of liability, new contract interpretations and other factors could result in increases in these liabilities, which could be material to our results of operations. We are unable to reliably estimate the amount of additional net loss or the range of net loss that is reasonably possible.

Notes payable and other borrowi

Notes payable and other borrowings	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Notes payable and other borrowings	(1 7 ) Notes payable and other borrowings Notes payable and other borrowings are summarized below (in millions). The weighted average interest rates and maturity date ranges shown in the following tables are based on borrowings as of December 31, 2020. Weighted Average December 31, Interest Rate 2020 2019 Insurance and other: Berkshire Hathaway Inc. (“Berkshire”): U.S. Dollar denominated due 2021-2047 3.2 % $ 8,308 $ 8,324 Euro denominated due 2021-2035 1.0 % 8,326 7,641 Japanese Yen denominated due 2023-2060 0.7 % 6,031 3,938 Berkshire Hathaway Finance Corporation (“BHFC”): U.S. Dollar denominated due 2021-2050 3.7 % 10,766 8,679 Great Britain Pound denominated due 2039-2059 2.5 % 2,347 2,274 Other subsidiary borrowings due 2021-2045 4.2 % 4,682 5,262 Short-term subsidiary borrowings 2.5 % 1,062 1,472 $ 41,522 $ 37,590 In March 2020, Berkshire repaid €1.0 billion of maturing senior notes and issued €1.0 billion of 0.0% senior notes due in 2025. In April 2020, Berkshire issued ¥195.5 billion (approximately $1.8 billion) of senior notes with maturity dates ranging from 2023 to 2060 and a weighted average interest rate of 1.07%. Borrowings of BHFC, a wholly owned finance subsidiary of Berkshire, consist of senior unsecured notes used to fund manufactured housing loans originated or acquired and equipment held for lease of certain subsidiaries. BHFC borrowings are fully and unconditionally guaranteed by Berkshire. During 2020, BHFC repaid $900 million of maturing senior notes and issued $3.0 billion of senior notes consisting of $500 million of 1.85% notes due in 2030, $750 million of 1.45% notes due in 2030 and $1.75 billion of 2.85% notes due in 2050. The carrying values of Berkshire and BHFC non-U.S. Dollar denominated senior notes (€6.85 billion, £1.75 billion and ¥625.5 billion par) reflect the applicable exchange rates as of the balance sheet dates. The effects of changes in foreign currency exchange rates during the period are recorded in earnings as a component of selling, general and administrative expenses. Changes in the exchange rates resulted in pre-tax losses of approximately $1.0 billion in 2020 and pre-tax gains of $192 million in 2019 and $366 million in 2018. Notes to Consolidated Financial Statements (Continued) (1 7 ) Notes payable and other borrowings (Continued) In addition to BHFC borrowings, Berkshire guaranteed approximately $1.2 billion of other subsidiary borrowings at December 31, 2020. Generally, Berkshire’s guarantee of a subsidiary’s debt obligation is an absolute, unconditional and irrevocable guarantee for the full and prompt payment when due of all payment obligations. Weighted Average December 31, Interest Rate 2020 2019 Railroad, utilities and energy: Berkshire Hathaway Energy Company (“BHE”) and subsidiaries: BHE senior unsecured debt due 2021-2051 4.2 % $ 13,447 $ 8,581 Subsidiary and other debt due 2021-2064 4.1 % 36,420 30,772 Short-term borrowings 1.8 % 2,286 3,214 Burlington Northern Santa Fe ("BNSF") and subsidiaries due 2021-2097 4.6 % 23,220 23,211 $ 75,373 $ 65,778 BHE subsidiary debt represents amounts issued pursuant to separate financing agreements. Substantially all of the assets of certain BHE subsidiaries are, or may be, pledged or encumbered to support or otherwise secure debt. These borrowing arrangements generally contain various covenants, including covenants which pertain to leverage ratios, interest coverage ratios and/or debt service coverage ratios. In November 2020, BHE’s subsidiary debt increased $5.6 billion for the debt assumed in connection with the Dominion pipeline business acquisition. See Note 2 to the Consolidated Financial Statements. During 2020, BHE and its subsidiaries also issued new term debt of approximately $7.6 billion with maturity dates ranging from 2025 to 2062 and a weighted average interest rate of 3.2% and repaid $3.2 billion of term debt and reduced short-term borrowings. BNSF’s borrowings are primarily senior unsecured debentures. During 2020, BNSF issued $575 million of 3.05% senior unsecured debentures due in 2051 and repaid debt of $570 million. As of December 31, 2020, BNSF, BHE and their subsidiaries were in compliance with all applicable debt covenants. Berkshire does not guarantee any debt, borrowings or lines of credit of BNSF, BHE or their subsidiaries. As of December 31, 2020, our subsidiaries had unused lines of credit and commercial paper capacity aggregating approximately $9.3 billion to support short-term borrowing programs and provide additional liquidity. Such unused lines of credit included approximately $8.2 billion related to BHE and its subsidiaries. Debt principal repayments expected during each of the next five years are as follows (in millions). Amounts in 2021 include short-term borrowings. 2021 2022 2023 2024 2025 Insurance and other $ 4,354 $ 1,593 $ 6,021 $ 2,343 $ 2,817 Railroad, utilities and energy 5,044 3,405 4,792 3,965 3,777 $ 9,398 $ 4,998 $ 10,813 $ 6,308 $ 6,594

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income taxes	(1 8 ) Income taxes The liabilities for income taxes reflected in our Consolidated Balance Sheets are as follows (in millions). December 31, 2020 2019 Currently payable (receivable) $ (276 ) $ 24 Deferred 73,261 65,823 Other 1,113 952 $ 74,098 $ 66,799 Notes to Consolidated Financial Statements (Continued) (1 8 ) Income taxes (Continued) The tax effects of temporary differences that give rise to significant portions of deferred tax assets and deferred tax liabilities are shown below (in millions). December 31, 2020 2019 Deferred tax liabilities: Investments – unrealized appreciation and cost basis differences $ 40,181 $ 32,134 Deferred charges reinsurance assumed 2,613 2,890 Property, plant and equipment and equipment held for lease 30,203 29,388 Goodwill and other intangible assets 6,753 7,293 Other 3,736 3,144 83,486 74,849 Deferred tax assets: Unpaid losses and loss adjustment expenses (1,135 ) (1,086 ) Unearned premiums (900 ) (853 ) Accrued liabilities (2,193 ) (1,981 ) Regulatory liabilities (1,421 ) (1,610 ) Other (4,576 ) (3,496 ) (10,225 ) (9,026 ) Net deferred tax liability $ 73,261 $ 65,823 We have not established deferred income taxes on accumulated undistributed earnings of certain foreign subsidiaries, which are expected to be reinvested indefinitely. Repatriation of all accumulated earnings of foreign subsidiaries would be impracticable to the extent that such earnings represent capital to support normal business operations. Generally, no U.S. federal income taxes will be imposed on future distributions of foreign earnings under current law. However, distributions to the U.S. or other foreign jurisdictions could be subject to withholding and other local taxes. On December 22, 2017, legislation known as the Tax Cuts and Jobs Act of 2017 (“TCJA”) was enacted. Among its provisions, the TCJA reduced the statutory U.S. Corporate income tax rate from 35% to 21% effective January 1, 2018 and provided for a one-time tax on certain accumulated undistributed post-1986 earnings of foreign subsidiaries. These effects were largely recorded in 2017 upon the enactment. In 2018, we reduced our estimate of the income taxes on the deemed repatriation of earnings of foreign subsidiaries and recognized additional deferred income tax rate change effects. Income tax expense reflected in our Consolidated Statements of Earnings for each of the three years ending December 31, 2020 is as follows (in millions). 2020 2019 2018 Federal $ 10,596 $ 19,069 $ (1,613 ) State 1,086 625 175 Foreign 758 1,210 1,117 $ 12,440 $ 20,904 $ (321 ) Current $ 5,052 $ 5,818 $ 5,176 Deferred 7,388 15,086 (5,497 ) $ 12,440 $ 20,904 $ (321 ) Notes to Consolidated Financial Statements (Continued) (1 8 ) Income taxes (Continued) Income tax expense is reconciled to hypothetical amounts computed at the U.S. federal statutory rate for each of the three years ending December 31, 2020 in the table below (in millions). 2020 2019 2018 Earnings before income taxes $ 55,693 $ 102,696 $ 4,001 Hypothetical income tax expense computed at the U.S. federal statutory rate $ 11,696 $ 21,566 $ 840 Dividends received deduction and tax-exempt interest (448 ) (433 ) (393 ) State income taxes, less U.S. federal income tax benefit 858 494 138 Foreign tax rate differences 13 (6 ) 271 U.S. income tax credits (1,519 ) (942 ) (711 ) Net benefit from the enactment of the TCJA — — (302 ) Goodwill impairments 1,977 20 21 Other differences, net (137 ) 205 (185 ) $ 12,440 $ 20,904 $ (321 ) Effective income tax rate 22.3 % 20.4 % (8.0 )% We file income tax returns in the United States and in state, local and foreign jurisdictions. We have settled income tax liabilities with the U.S. federal taxing authority (“IRS”) for tax years through 2011 and the tax years 2012 and 2013 remain open. The IRS is auditing Berkshire’s consolidated U.S. federal income tax returns for the 2014 through 2016 tax years. We are also under audit or subject to audit with respect to income taxes in many state and foreign jurisdictions. It is reasonably possible that certain of these income tax examinations will be settled in 2021. We currently do not believe that the outcome of unresolved issues or claims will be material to our Consolidated Financial Statements. At December 31, 2020 and 2019, net unrecognized tax benefits were $1,113 million and $952 million, respectively. Included in the balance at December 31, 2020, were $920 million of tax positions that, if recognized, would impact the effective tax rate. The remaining balance in net unrecognized tax benefits principally relates to tax positions where the ultimate recognition is highly certain but there is uncertainty about the timing of recognition. Because of the impact of deferred income tax accounting, these positions, when recognized, would not affect the annual effective income tax rate. We recorded income tax expense of $60 million in 2020 and $377 million in 2019 for uncertain tax positions related to investments by a subsidiary in certain tax equity investment funds that generated income tax benefits from 2015 through 2018. We now believe that it is more likely than not those income tax benefits are not valid. We do not expect any material increases to the estimated amount of unrecognized tax benefits during 2021.

Dividend restrictions - Insuran

Dividend restrictions - Insurance subsidiaries	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Dividend restrictions - Insurance subsidiaries	( 19 ) Dividend restrictions – Insurance subsidiaries Payments of dividends by our insurance subsidiaries are restricted by insurance statutes and regulations. Without prior regulatory approval, our principal insurance subsidiaries may declare up to approximately $23 billion as ordinary dividends during 2021. Investments in fixed maturity and equity securities and short-term investments on deposit with U.S. state insurance authorities in accordance with state insurance regulations were approximately $5.5 billion at December 31, 2020 and $6.3 billion at December 31, 2019. Combined shareholders’ equity of U.S. based insurance subsidiaries determined pursuant to statutory accounting rules (Surplus as Regards Policyholders) was approximately $237 billion at December 31, 2020 and $216 billion at December 31, 2019. Statutory surplus differs from the corresponding amount based on GAAP, due to differences in accounting for certain assets and liabilities. For instance, deferred charges reinsurance assumed, deferred policy acquisition costs, unrealized gains on certain investments and related deferred income taxes are recognized for GAAP but not for statutory reporting purposes. In addition, the carrying values of certain assets, such as goodwill and non-insurance entities owned by our insurance subsidiaries, are not fully recognized for statutory reporting purposes.

Fair value measurements

Fair value measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair value measurements	Notes to Consolidated Financial Statements (Continued) (2 0 ) Fair value measurements Our financial assets and liabilities are summarized below as of December 31, 2020 and December 31, 2019, with fair values shown according to the fair value hierarchy (in millions). The carrying values of cash and cash equivalents, U.S. Treasury Bills, receivables and accounts payable, accruals and other liabilities are considered to be reasonable estimates of their fair values. Carrying Value Fair Value Quoted Prices (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2020 Investments in fixed maturity securities: U.S. Treasury, U.S. government corporations and agencies $ 3,403 $ 3,403 $ 3,358 $ 45 $ — Foreign governments 11,338 11,338 9,259 2,079 — Corporate bonds 5,191 5,191 — 5,191 — Other 478 478 — 478 — Investments in equity securities 281,170 281,170 271,848 38 9,284 Investment in Kraft Heinz common stock 13,336 11,280 11,280 — — Loans and finance receivables 19,201 20,554 — 2,692 17,862 Derivative contract assets (1) 270 270 1 72 197 Derivative contract liabilities: Railroad, utilities and energy (1) 121 121 6 96 19 Equity index put options 1,065 1,065 — — 1,065 Notes payable and other borrowings: Insurance and other 41,522 46,676 — 46,665 11 Railroad, utilities and energy 75,373 92,593 — 92,593 — December 31, 2019 Investments in fixed maturity securities: U.S. Treasury, U.S. government corporations and agencies $ 3,090 $ 3,090 $ 3,046 $ 44 $ — Foreign governments 8,638 8,638 5,437 3,201 — Corporate bonds 6,352 6,352 — 6,350 2 Other 605 605 — 605 — Investments in equity securities 248,027 248,027 237,271 46 10,710 Investment in Kraft Heinz common stock 13,757 10,456 10,456 — — Loans and finance receivables 17,527 17,861 — 1,809 16,052 Derivative contract assets (1) 145 145 — 23 122 Derivative contract liabilities: Railroad, utilities and energy (1) 76 76 6 59 11 Equity index put options 968 968 — — 968 Notes payable and other borrowings: Insurance and other 37,590 40,589 — 40,569 20 Railroad, utilities and energy 65,778 76,237 — 76,237 — (1) Notes to Consolidated Financial Statements (Continued) (2 0 ) Fair value measurements (Continued) The fair values of substantially all of our financial instruments were measured using market or income approaches. The hierarchy for measuring fair value consists of Levels 1 through 3, which are described below. Level 1 Level 2 Level 3 Reconciliations of assets and liabilities measured and carried at fair value on a recurring basis with the use of significant unobservable inputs (Level 3) for each of the three years ending December 31, 2020 follow (in millions). Investments in equity and fixed maturity securities Net derivative contract liabilities Balance December 31, 2017 $ 6 $ (2,069 ) Gains (losses) included in: Earnings — (118 ) Other comprehensive income — 2 Regulatory assets and liabilities — 3 Acquisitions 2 3 Dispositions and settlements (1 ) (164 ) Balance December 31, 2018 7 (2,343 ) Gains (losses) included in: Earnings 404 1,972 Other comprehensive income — (1 ) Regulatory assets and liabilities — (26 ) Acquisitions 10,000 6 Dispositions and settlements (4 ) (465 ) Balance December 31, 2019 10,407 (857 ) Gains (losses) included in: Earnings (1,426 ) 603 Other comprehensive income — — Regulatory assets and liabilities — (17 ) Acquisitions — 5 Dispositions and settlements (2 ) (621 ) Balance December 31, 2020 $ 8,979 $ (887 ) Notes to Consolidated Financial Statements (Continued) (2 0 ) Fair value measurements (Continued) We acquired investments in Occidental Cumulative Perpetual Preferred Stock (“Occidental Preferred”) and Occidental common stock warrants in August 2019 at an aggregate cost of $10 billion. We currently consider the related fair value measurements to contain Level 3 inputs. See Note 4 for information regarding these investments. Quantitative information as of December 31, 2020, with respect to assets and liabilities measured and carried at fair value on a recurring basis with the use of significant unobservable inputs (Level 3) follows (in millions). Fair Value Principal Valuation Techniques Unobservable Inputs Weighted Average Investments in equity securities: Preferred stock $ 8,891 Discounted cash flow Expected duration 9 years Discount for transferability restrictions and subordination 375 bps Common stock warrants 86 Warrant pricing model Expected duration 9 years Volatility 32% Derivative contract liabilities 1,065 Option pricing model Volatility 19% Investments in equity securities in the preceding table include our investments in the Occidental Preferred and Occidental common stock warrants. These investments are subject to contractual restrictions on transferability and contain provisions that currently prevent us from economically hedging our investments. In applying discounted cash flow techniques in valuing the Occidental Preferred, we made assumptions regarding the expected duration of the investment. The Occidental Preferred is redeemable at Occidental’s option beginning in 2029. We also made estimates regarding the impact of subordination, as the Occidental Preferred has a lower priority in liquidation than debt instruments. In valuing the Occidental common stock warrants, we used a warrant valuation model. While most of the inputs to the model are observable, we made assumptions regarding the expected duration and volatility of the warrants. The Occidental common stock warrants contractually expire on the one-year anniversary on which no Occidental Preferred remains outstanding. Our equity index put option contracts are illiquid and contain contract terms that are not standard in derivatives markets. For example, we are not required to post collateral under most of our contracts. We determine the fair value of the equity index put option contract liabilities based on the Black-Scholes option valuation model.

Accumulated other comprehensive

Accumulated other comprehensive income	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Accumulated other comprehensive income	(2 1 ) Accumulated other comprehensive income A summary of the net changes in after-tax accumulated other comprehensive income attributable to Berkshire Hathaway shareholders for each of the three years ending December 31, 2020 follows (in millions). Unrealized appreciation of investments, net Foreign currency translation Defined benefit pension plans Other Accumulated other comprehensive income Balance December 31, 2017 $ 62,093 $ (3,114 ) $ (420 ) $ 12 $ 58,571 Reclassifications to retained earnings upon adoption of new accounting standards (61,340 ) (65 ) 36 (6 ) (61,375 ) Other comprehensive income, net (383 ) (1,424 ) (432 ) 28 (2,211 ) Balance December 31, 2018 370 (4,603 ) (816 ) 34 (5,015 ) Other comprehensive income, net 111 257 (553 ) (43 ) (228 ) Balance December 31, 2019 481 (4,346 ) (1,369 ) (9 ) (5,243 ) Other comprehensive income, net 55 1,264 (276 ) (43 ) 1,000 Balance December 31, 2020 $ 536 $ (3,082 ) $ (1,645 ) $ (52 ) $ (4,243 )

Common stock

Common stock	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Common stock	(2 2 ) Common stock Changes in Berkshire’s issued, treasury and outstanding common stock during the three years ending December 31, 2020 are shown in the table below. In addition to our common stock, 1,000,000 shares of preferred stock are authorized, but none are issued. Class A, $5 Par Value (1,650,000 shares authorized) Class B, $0.0033 Par Value (3,225,000,000 shares authorized) Issued Treasury Outstanding Issued Treasury Outstanding Balance December 31, 2017 762,755 (11,680 ) 751,075 1,342,066,749 (1,409,762 ) 1,340,656,987 Conversions of Class A common stock to Class B common stock and exercises of replacement stock options (20,542 ) — (20,542 ) 31,492,234 — 31,492,234 Treasury stock acquired — (1,217 ) (1,217 ) — (4,729,147 ) (4,729,147 ) Balance December 31, 2018 742,213 (12,897 ) 729,316 1,373,558,983 (6,138,909 ) 1,367,420,074 Conversions of Class A common stock to Class B common stock and exercises of replacement stock options (22,906 ) — (22,906 ) 34,624,869 — 34,624,869 Treasury stock acquired — (4,440 ) (4,440 ) — (17,563,410 ) (17,563,410 ) Balance December 31, 2019 719,307 (17,337 ) 701,970 1,408,183,852 (23,702,319 ) 1,384,481,533 Conversions of Class A common stock to Class B common stock and exercises of replacement stock options (40,784 ) — (40,784 ) 61,176,000 — 61,176,000 Treasury stock acquired — (17,255 ) (17,255 ) — (95,614,062 ) (95,614,062 ) Balance December 31, 2020 678,523 (34,592 ) 643,931 1,469,359,852 (119,316,381 ) 1,350,043,471 Each Class A common share is entitled to one vote per share. Class B common stock possesses dividend and distribution rights equal to one-fifteen-hundredth (1/1,500) (1/10,000) Since we have two classes of common stock, we provide earnings per share data on the Consolidated Statements of Earnings for average equivalent Class A shares outstanding and average equivalent Class B shares outstanding. Class B shares are economically equivalent to one-fifteen-hundredth (1/1,500) (1/1,500) Berkshire’s common stock repurchase program, as amended, permits Berkshire to repurchase shares any time that Warren Buffett, Berkshire’s Chairman of the Board and Chief Executive Officer, and Charlie Munger, Vice Chairman of the Board, believe that the repurchase price is below Berkshire’s intrinsic value, conservatively determined. The program continues to allow share repurchases in the open market or through privately negotiated transactions and does not specify a maximum number of shares to be repurchased. However, repurchases will not be made if they would reduce the total value of Berkshire’s consolidated cash, cash equivalents and U.S. Treasury Bill holdings below $20 billion. The repurchase program does not obligate Berkshire to repurchase any specific dollar amount or number of Class A or Class B shares and there is no expiration date to the program.

Revenues from contracts with cu

Revenues from contracts with customers	12 Months Ended
	Dec. 31, 2020
Revenue From Contract With Customer [Abstract]
Revenues from contracts with customers	(2 3 ) Revenues from contracts with customers We recognize revenue when a good or service is transferred to a customer. A good or service is transferred when or as the customer obtains control of that good or service. Revenues are based on the consideration we expect to receive in connection with our promises to deliver goods and services to our customers. Notes to Consolidated Financial Statements (Continued) (23) Revenues from contracts with customers (Continued) The following tables summarize customer contract revenues disaggregated by reportable segment and the source of the revenue for each of the three years ended December 31, 2020 (in millions). Other revenues included in consolidated revenues were primarily insurance premiums earned, interest, dividend and other investment income and leasing revenues, which are not considered to be revenues from contracts with customers under GAAP. 2020 Manufacturing McLane Company Service and retailing BNSF Berkshire Hathaway Energy Insurance, Corporate and other Total Manufactured products: Industrial and commercial products $ 20,772 $ — $ 192 $ — $ — $ — $ 20,964 Building products 15,943 — — — — — 15,943 Consumer products 14,757 — — — — — 14,757 Grocery and convenience store distribution — 30,795 — — — — 30,795 Food and beverage distribution — 15,368 — — — — 15,368 Auto sales — — 8,258 — — — 8,258 Other retail and wholesale distribution 2,452 — 12,470 — — — 14,922 Service 1,456 584 3,332 20,693 4,595 — 30,660 Electricity and natural gas — — — — 15,066 — 15,066 Total 55,380 46,747 24,252 20,693 19,661 — 166,733 Other revenues 3,598 93 3,859 57 1,353 69,817 78,777 $ 58,978 $ 46,840 $ 28,111 $ 20,750 $ 21,014 $ 69,817 $ 245,510 2019 Manufactured products: Industrial and commercial products $ 25,311 $ — $ 184 $ — $ — $ — $ 25,495 Building products 15,620 — — — — — 15,620 Consumer products 14,120 — — — — — 14,120 Grocery and convenience store distribution — 33,057 — — — — 33,057 Food and beverage distribution — 16,767 — — — — 16,767 Auto sales — — 8,481 — — — 8,481 Other retail and wholesale distribution 2,299 — 12,213 — — — 14,512 Service 1,642 539 4,062 23,302 4,096 — 33,641 Electricity and natural gas — — — — 14,819 — 14,819 Total 58,992 50,363 24,940 23,302 18,915 — 176,512 Other revenues 3,632 95 4,459 55 1,181 68,682 78,104 $ 62,624 $ 50,458 $ 29,399 $ 23,357 $ 20,096 $ 68,682 $ 254,616 2018 Manufactured products: Industrial and commercial products $ 25,707 $ — $ 204 $ — $ — $ — $ 25,911 Building products 14,323 — — — — — 14,323 Consumer products 14,790 — — — — — 14,790 Grocery and convenience store distribution — 33,518 — — — — 33,518 Food and beverage distribution — 16,309 — — — — 16,309 Auto sales — — 8,181 — — — 8,181 Other retail and wholesale distribution 2,091 — 12,067 — — — 14,158 Service 1,519 84 4,100 23,652 3,949 — 33,304 Electricity and natural gas — — — — 14,951 — 14,951 Total 58,430 49,911 24,552 23,652 18,900 — 175,445 Other revenues 3,340 76 4,297 51 1,070 63,558 72,392 $ 61,770 $ 49,987 $ 28,849 $ 23,703 $ 19,970 $ 63,558 $ 247,837 Notes to Consolidated Financial Statements (Continued) (23) Revenues from contracts with customers (Continued) A summary of the transaction price allocated to the significant unsatisfied remaining performance obligations relating to contracts with expected durations in excess of one year as of December 31, 2020 and the timing of when the performance obligations are expected to be satisfied follows (in millions). Less than 12 months Greater than 12 months Total Electricity and natural gas $ 3,210 $ 22,088 $ 25,298 Other sales and service contracts 1,228 2,382 3,610

Pension plans

Pension plans	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Pension plans	(2 4 ) Pension plans Certain of our subsidiaries sponsor defined benefit pension plans. Benefits under the plans are generally based on years of service and compensation or fixed benefit rates. Plan sponsors may make contributions to the plans to meet regulatory requirements and may also make discretionary contributions. The components of our net periodic pension expense for each of the three years ending December 31, 2020 follow (in millions). 2020 2019 2018 Service cost $ 235 $ 224 $ 271 Interest cost 510 618 593 Expected return on plan assets (955 ) (936 ) (988 ) Amortization of actuarial losses and other 171 26 188 Net periodic pension expense $ (39 ) $ (68 ) $ 64 The projected benefit obligation (“PBO”) is the actuarial present value of benefits earned based upon service and compensation prior to the valuation date and, if applicable, includes assumptions regarding future compensation levels. Benefit obligations under qualified U.S. defined benefit pension plans are funded through assets held in trusts. Pension obligations under certain non-U.S. plans and non-qualified U.S. plans are unfunded and the aggregate PBOs of such plans were approximately $1.6 billion and $1.3 billion as of December 31, 2020 and 2019, respectively. The cost of pension plans covering employees of certain regulated subsidiaries of BHE are generally recoverable through the regulated rate making process. The funded status at year end 2020 and 2019 and reconciliations of the changes in PBOs and plan assets related to BHE’s pension plans and all other pension plans for each of the two years ending December 31, 2020 follow (in millions). 2020 2019 BHE Other Total BHE Other Total Benefit obligations PBO beginning of year $ 4,898 $ 13,808 $ 18,706 $ 4,551 $ 12,371 $ 16,922 Service cost 33 202 235 32 192 224 Interest cost 133 377 510 161 457 618 Benefits paid (285 ) (709 ) (994 ) (257 ) (776 ) (1,033 ) Settlements (63 ) (12 ) (75 ) (121 ) (46 ) (167 ) Actuarial (gains) or losses and other 566 1,481 2,047 532 1,610 2,142 PBO end of year $ 5,282 $ 15,147 $ 20,429 $ 4,898 $ 13,808 $ 18,706 Plan assets Plan assets beginning of year $ 4,808 $ 11,688 $ 16,496 $ 4,385 $ 10,574 $ 14,959 Employer contributions 69 127 196 68 131 199 Benefits paid (285 ) (709 ) (994 ) (257 ) (776 ) (1,033 ) Actual return on plan assets 554 1,820 2,374 650 1,764 2,414 Settlements (63 ) (12 ) (75 ) (121 ) (46 ) (167 ) Other 75 (134 ) (59 ) 83 41 124 Plan assets end of year $ 5,158 $ 12,780 $ 17,938 $ 4,808 $ 11,688 $ 16,496 Funded status – net liability $ 124 $ 2,367 $ 2,491 $ 90 $ 2,120 $ 2,210 Notes to Consolidated Financial Statements (Continued) (2 4 ) Pension plans (Continued) The funded status reflected in assets was $1,351 million and in liabilities was $3,842 million at December 31, 2020. The funded status included in assets was $857 million and in liabilities was $3,067 million at December 31, 2019. The accumulated benefit obligation (“ABO”) is the actuarial present value of benefits earned based on service and compensation prior to the valuation date. The ABO was $19.4 billion at December 31, 2020 and $17.5 billion at December 31, 2019. Information for plans with PBOs and ABOs in excess of plan assets as of December 31, 2020 and 2019 follows (in millions) 2020 2019 PBOs $ 12,775 $ 12,625 Plan assets 9,018 9,627 ABOs 10,875 10,617 Plan assets 7,820 8,367 Weighted average assumptions used in determining PBOs and net periodic pension expense follow. 2020 2019 2018 Discount rate applicable to pension benefit obligations 2.3 % 3.1 % 3.9 % Expected long-term rate of return on plan assets 6.2 6.4 6.4 Rate of compensation increase 2.6 2.5 2.6 Discount rate applicable to net periodic pension expense 3.1 4.0 3.4 Pension Fair value measurements of plan assets as of December 31, 2020 and 2019 follow (in millions). Fair Value Investment funds and partnerships Total Level 1 Level 2 Level 3 at net asset value December 31, 2020 Cash and cash equivalents $ 383 $ 243 $ 140 $ — $ — Equity securities 11,383 10,123 851 409 — Fixed maturity securities 3,173 2,214 926 33 — Investment funds and other 2,999 198 398 56 2,347 $ 17,938 $ 12,778 $ 2,315 $ 498 $ 2,347 December 31, 2019 Cash and cash equivalents $ 412 $ 309 $ 103 $ — $ — Equity securities 11,105 9,860 836 409 — Fixed maturity securities 2,328 1,593 704 31 — Investment funds and other 2,651 143 358 40 2,110 $ 16,496 $ 11,905 $ 2,001 $ 480 $ 2,110 See Note 20 for a discussion of the three levels of fair value measurements. Plan assets are generally invested with the long-term objective of producing earnings to adequately cover expected benefit obligations, while assuming a prudent level of risk. Allocations may change due to changing market conditions and investment opportunities. The expected rates of return on plan assets reflect subjective assessments of expected long-term investment returns. Generally, past investment returns are not given significant consideration when establishing assumptions for expected long-term rates of return on plan assets. Actual experience will differ from the assumed rates of return. Notes to Consolidated Financial Statements (Continued) (2 4 ) Pension plans (Continued) A reconciliation of the pre-tax accumulated other comprehensive income (loss) related to defined benefit pension plans for each of the two years ending December 31, 2020 follows (in millions). 2020 2019 Balance beginning of year $ (1,896 ) $ (1,184 ) Amount included in net periodic pension expense 141 94 Actuarial gains (losses) and other (496 ) (806 ) Balance end of year $ (2,251 ) $ (1,896 ) Several of our subsidiaries also sponsor defined contribution retirement plans, such as 401(k) or profit-sharing plans. Employee contributions are subject to regulatory limitations and the specific plan provisions. Several plans provide for employer matching contributions up to levels specified in the plans and provide for additional discretionary contributions as determined by management. Our defined contribution plan expense was approximately $1.4 billion in 2020, $1.2 billion in 2019 and $1.0 billion in 2018.

Contingencies and Commitments

Contingencies and Commitments	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Contingencies and Commitments	(2 5 ) Contingencies and Commitments We are parties in a variety of legal actions that routinely arise out of the normal course of business, including legal actions seeking to establish liability directly through insurance contracts or indirectly through reinsurance contracts issued by Berkshire subsidiaries. Plaintiffs occasionally seek punitive or exemplary damages. We do not believe that such normal and routine litigation will have a material effect on our financial condition or results of operations. Berkshire and certain of its subsidiaries are also involved in other kinds of legal actions, some of which assert or may assert claims or seek to impose fines and penalties. We believe that any liability that may arise as a result of other pending legal actions will not have a material effect on our consolidated financial condition or results of operations. Our subsidiaries regularly make commitments in the ordinary course of business to purchase goods and services used in their businesses. As of December 31, 2020, estimated future payments under such arrangements were as follows: $14.6 billion in 2021, $4.5 billion in 2022, $3.4 billion in 2023, $2.8 billion in 2024, $3.1 billion in 2025 and $20.0 billion after 2025. The most significant of these relate to our railroad, utilities and energy businesses and our shared aircraft ownership and leasing business. Pursuant to the terms of agreements with noncontrolling shareholders in our less than wholly-owned subsidiaries, we may be obligated to acquire their equity interests. If we had acquired all outstanding noncontrolling interests as of December 31, 2020, we estimate the cost would have been approximately $6.3 billion. However, the timing and the amount of any such future payments that might be required are contingent on future actions of the noncontrolling owners.

Supplemental cash flow informat

Supplemental cash flow information	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental cash flow information	( 2 6 ) Supplemental cash flow information A summary of supplemental cash flow information for each of the three years ending December 31, 2020 is presented in the following table (in millions). 2020 2019 2018 Cash paid during the period for: Income taxes $ 5,001 $ 5,415 $ 4,354 Interest: Insurance and other 1,001 1,011 1,111 Railroad, utilities and energy 3,006 2,879 2,867 Non-cash investing and financing activities: Liabilities assumed in connection with business acquisitions 6,981 766 3,735 Operating lease liabilities arising from obtaining right-of-use assets 729 782 —

Business segment data

Business segment data	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Business segment data	Notes to Consolidated Financial Statements (Continued) (27) Business segment data Our operating businesses include a large and diverse group of insurance, manufacturing, service and retailing businesses. We organize our reportable business segments in a manner that reflects how management views those business activities. Certain businesses are grouped together for segment reporting based upon similar products or product lines, marketing, selling and distribution characteristics, even though those business units are operated under separate local management. The tabular information that follows shows data of reportable segments reconciled to amounts reflected in our Consolidated Financial Statements. Intersegment transactions are not eliminated from segment results when management considers those transactions in assessing the results of the respective segments. Furthermore, our management does not consider investment and derivative gains/losses, impairments or amortization of certain business acquisition accounting adjustments related to Berkshire’s business acquisitions or certain other corporate income and expense items in assessing the financial performance of operating units. Collectively, these items are included in reconciliations of segment amounts to consolidated amounts. Berkshire’s operating segments are as follows. Business Identity Business Activity Insurance: GEICO Underwriting private passenger automobile insurance mainly by direct response methods Berkshire Hathaway Primary Group Underwriting multiple lines of property and casualty insurance policies for primarily commercial accounts Berkshire Hathaway Reinsurance Group Underwriting excess-of-loss, quota-share and facultative reinsurance worldwide BNSF Operation of one of the largest railroad systems in North America Berkshire Hathaway Energy Regulated electric and gas utility, including power generation and distribution activities and real estate brokerage activities Manufacturing Manufacturers of numerous products including industrial, consumer and building products, including home building and related financial services McLane Company Wholesale distribution of groceries and non-food items Service and retailing Providers of numerous services including shared aircraft ownership programs, aviation pilot training, electronic components distribution, various retailing businesses, including automobile dealerships and trailer and furniture leasing Notes to Consolidated Financial Statements (Continued) (27) Business segment data (Continued) A disaggregation of our consolidated data for each of the three most recent years is presented as follows (in millions). Revenues Earnings before income taxes 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance: Underwriting: GEICO $ 35,093 $ 35,572 $ 33,363 $ 3,428 $ 1,506 $ 2,449 Berkshire Hathaway Primary Group 9,615 9,165 8,111 110 383 670 Berkshire Hathaway Reinsurance Group 18,693 16,341 15,944 (2,700 ) (1,472 ) (1,109 ) Insurance underwriting 63,401 61,078 57,418 838 417 2,010 Investment income 5,960 6,615 5,518 5,949 6,600 5,503 Total insurance 69,361 67,693 62,936 6,787 7,017 7,513 BNSF 20,869 23,515 23,855 6,792 7,250 6,863 Berkshire Hathaway Energy 21,031 20,114 19,987 2,479 2,618 2,472 Manufacturing 59,079 62,730 61,883 8,010 9,522 9,366 McLane Company 46,840 50,458 49,987 251 288 246 Service and retailing 28,178 29,487 28,939 2,628 2,555 2,696 245,358 253,997 247,587 26,947 29,250 29,156 Reconciliation to consolidated amount Investment and derivative gains/losses — — — 40,746 72,607 (22,455 ) Interest expense, not allocated to segments — — — (483 ) (416 ) (458 ) Equity method investments — — — 726 1,176 (2,167 ) Goodwill and intangible asset impairments — — — (10,671 ) (96 ) (382 ) Corporate, eliminations and other 152 619 250 (1,572 ) 175 307 $ 245,510 $ 254,616 $ 247,837 $ 55,693 $ 102,696 $ 4,001 Interest expense Income tax expense 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance $ — $ — $ — $ 1,089 $ 1,166 $ 1,374 BNSF 1,037 1,070 1,041 1,631 1,769 1,644 Berkshire Hathaway Energy 1,941 1,835 1,777 (1,010 ) (526 ) (452 ) Manufacturing 737 752 690 1,795 2,253 2,188 McLane Company — — 15 71 71 59 Service and retailing 61 86 91 669 603 634 3,776 3,743 3,614 4,245 5,336 5,447 Reconciliation to consolidated amount Investment and derivative gains/losses — — — 8,855 15,159 (4,673 ) Interest expense, not allocated to segments 483 416 458 (102 ) (88 ) (96 ) Equity method investments — — — 57 148 (753 ) Corporate, eliminations and other (176 ) (198 ) (219 ) (615 ) 349 (246 ) $ 4,083 $ 3,961 $ 3,853 $ 12,440 $ 20,904 $ (321 ) Notes to Consolidated Financial Statements (Continued) (27) Business segment data (Continued) Capital expenditures Depreciation of tangible assets 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance $ 50 $ 108 $ 130 $ 74 $ 82 $ 79 BNSF 3,063 3,608 3,187 2,423 2,350 2,268 Berkshire Hathaway Energy 6,765 7,364 6,241 3,376 2,947 2,830 Manufacturing 2,133 2,981 3,116 2,026 1,951 1,890 McLane Company 98 158 276 204 225 204 Service and retailing 903 1,760 1,587 1,216 1,192 1,115 $ 13,012 $ 15,979 $ 14,537 $ 9,319 $ 8,747 $ 8,386 Goodwill at year-end Identifiable assets at year-end 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance $ 15,224 $ 15,289 $ 15,289 $ 399,169 $ 364,550 $ 289,746 BNSF 14,851 14,851 14,851 73,809 73,699 70,242 Berkshire Hathaway Energy 11,763 9,979 9,851 109,286 88,651 80,543 Manufacturing 25,512 34,800 34,019 104,318 104,437 99,912 McLane Company 232 734 734 6,771 6,872 6,243 Service and retailing 6,152 6,229 6,281 26,173 26,494 24,724 $ 73,734 $ 81,882 $ 81,025 719,526 664,703 571,410 Reconciliation to consolidated amount Corporate and other 80,469 71,144 55,359 Goodwill 73,734 81,882 81,025 $ 873,729 $ 817,729 $ 707,794 Property/casualty and life/health insurance premiums written and earned are summarized below (in millions). Property/Casualty Life/Health 2020 2019 2018 2020 2019 2018 Premiums Written: Direct $ 47,838 $ 47,578 $ 44,513 $ 510 $ 839 $ 1,111 Assumed 11,533 10,214 8,970 5,960 5,046 5,540 Ceded (898 ) (821 ) (869 ) (42 ) (45 ) (49 ) $ 58,473 $ 56,971 $ 52,614 $ 6,428 $ 5,840 $ 6,602 Premiums Earned: Direct $ 46,418 $ 46,540 $ 43,095 $ 510 $ 839 $ 1,111 Assumed 11,449 9,643 8,649 5,973 4,952 5,438 Ceded (907 ) (851 ) (825 ) (42 ) (45 ) (50 ) $ 56,960 $ 55,332 $ 50,919 $ 6,441 $ 5,746 $ 6,499 Notes to Consolidated Financial Statements (Continued) (27) Business segment data (Continued) Insurance premiums written by geographic region (based upon the domicile of the insured or reinsured) are summarized below (in millions). Property/Casualty Life/Health 2020 2019 2018 2020 2019 2018 United States $ 50,250 $ 50,529 $ 46,146 $ 2,820 $ 2,553 $ 3,598 Western Europe 3,751 2,535 2,157 1,120 908 939 Asia Pacific 3,410 3,114 3,726 1,652 1,582 1,361 All other 1,062 793 585 836 797 704 $ 58,473 $ 56,971 $ 52,614 $ 6,428 $ 5,840 $ 6,602 Consolidated sales, service and leasing revenues were $132.3 billion in 2020, $140.8 billion in 2019 and $139.1 billion in 2018. Sales, service and leasing revenues attributable to the United States were 86% in 2020, 85% in 2019 and 84% in 2018 of such amounts. The remainder of sales, service and leasing revenues were primarily in Europe, Canada and the Asia Pacific. Railroad, utilities and energy revenues were $41.8 billion in 2020, $43.5 billion in 2019 and $43.7 billion in 2018. In each of the three years, approximately 96% of such revenues were attributable to the United States. At December 31, 2020, approximately 89% of our consolidated net property, plant and equipment and equipment held for lease was located in the United States with the remainder primarily in Canada and the United Kingdom.

Quarterly data

Quarterly data	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly data	(28) Quarterly data A summary of revenues and net earnings by quarter for each of the last two years follows. This information is unaudited. Amounts are in millions, except per share amounts. 1 st Quarter 2 nd Quarter 3 rd Quarter 4 th Quarter 2020 Revenues $ 61,265 $ 56,840 $ 63,024 $ 64,381 Net earnings (loss) attributable to Berkshire shareholders * (49,746 ) 26,295 30,137 35,835 Net earnings (loss) attributable to Berkshire shareholders per equivalent Class A common share (30,653 ) 16,314 18,994 23,015 2019 Revenues $ 60,678 $ 63,598 $ 64,972 $ 65,368 Net earnings attributable to Berkshire shareholders * 21,661 14,073 16,524 29,159 Net earnings attributable to Berkshire shareholders per equivalent Class A common share 13,209 8,608 10,119 17,909 * Includes after-tax investment and derivative gains/losses as follows: 1 st Quarter 2 nd Quarter 3 rd Quarter 4 th Quarter 2020 $ (55,617 ) $ 31,645 $ 24,737 $ 30,826 2019 16,106 7,934 8,666 24,739

Condensed Financial Information

Condensed Financial Information	12 Months Ended
	Dec. 31, 2020
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Financial Information	BERKSHIRE HATHAWAY INC. (Parent Company) Condensed Financial Information (Dollars in millions) Schedule I Balance Sheets December 31, 2020 2019 Assets: Cash and cash equivalents $ 12,329 $ 15,004 Short-term investments in U.S. Treasury Bills 29,773 25,514 Investments in and advances to/from consolidated subsidiaries 411,826 392,162 Investment in The Kraft Heinz Company 13,336 13,757 Other assets 108 131 $ 467,372 $ 446,568 Liabilities and Shareholders’ Equity: Accounts payable, accrued interest and other liabilities $ 369 $ 320 Income taxes, principally deferred 1,174 1,554 Notes payable and other borrowings 22,665 19,903 24,208 21,777 Berkshire Hathaway shareholders’ equity 443,164 424,791 $ 467,372 $ 446,568 Statements of Earnings and Comprehensive Income Year ended December 31, 2020 2019 2018 Income items: From consolidated subsidiaries: Dividends and distributions $ 26,110 $ 15,603 $ 9,658 Undistributed earnings (losses) 17,402 65,237 (3,952 ) 43,512 80,840 5,706 Investment gains (losses) (24 ) (125 ) (4 ) Equity in net earnings (losses) of The Kraft Heinz Company 95 493 (2,730 ) Other income 328 780 649 43,911 81,988 3,621 Cost and expense items: General and administrative 194 122 216 Interest expense 489 591 601 Foreign exchange (gains) losses on non-U.S. Dollar denominated debt 970 (193 ) (366 ) Income tax expense (benefit) (263 ) 51 (851 ) 1,390 571 (400 ) Net earnings attributable to Berkshire Hathaway shareholders 42,521 81,417 4,021 Other comprehensive income attributable to Berkshire Hathaway shareholders 1,000 (228 ) (2,211 ) Comprehensive income attributable to Berkshire Hathaway shareholders $ 43,521 $ 81,189 $ 1,810 See Note to Condensed Financial Information BERKSHIRE HATHAWAY INC. (Parent Company) Condensed Financial Information (Dollars in millions) Schedule I (continued) Statements of Cash Flows Year ended December 31, 2020 2019 2018 Cash flows from operating activities: Net earnings attributable to Berkshire Hathaway shareholders $ 42,521 $ 81,417 $ 4,021 Adjustments to reconcile net earnings to cash flows from operating activities: Investment gains/losses 24 125 4 Undistributed earnings of consolidated subsidiaries (17,402 ) (65,237 ) 3,952 Non-cash dividends from subsidiaries (8,296 ) — — Income taxes payable (72 ) (56 ) (972 ) Other 1,100 (693 ) 3,062 Net cash flows from operating activities 17,875 15,556 10,067 Cash flows from investing activities: Investments in and advances to/from consolidated subsidiaries, net (1,947 ) 60 460 Purchases of U.S. Treasury Bills (54,715 ) (40,107 ) (29,740 ) Sales and maturities of U.S. Treasury Bills 59,035 36,943 21,442 Other 11 737 — Net cash flows from investing activities 2,384 (2,367 ) (7,838 ) Cash flows from financing activities: Proceeds from borrowings 2,923 3,967 17 Repayments of borrowings (1,151 ) (758 ) (1,563 ) Acquisition of treasury stock (24,706 ) (4,850 ) (1,346 ) Other — 19 61 Net cash flows from financing activities (22,934 ) (1,622 ) (2,831 ) Increase (decrease) in cash and cash equivalents (2,675 ) 11,567 (602 ) Cash and cash equivalents at beginning of year 15,004 3,437 4,039 Cash and cash equivalents at end of year $ 12,329 $ 15,004 $ 3,437 Other cash flow information: Income taxes paid $ 3,391 $ 3,531 $ 2,790 Interest paid 359 364 388 Note to Condensed Financial Information Berkshire currently owns 26.6% of the outstanding shares of The Kraft Heinz Company (“Kraft Heinz”) common stock, which is accounted for pursuant to the equity method. See Note 5 to the accompanying Consolidated Financial Statements for additional information regarding this investment. In 2020, the Parent Company repaid €1.0 billion of maturing senior notes and issued €1.0 billion of 0.0% senior notes due in 2025 and ¥195.5 billion (approximately $1.8 billion) of senior notes with maturity dates ranging from 2023 to 2060 with a weighted average interest rate of 1.07%. As of December 31, 2020, the Parent Company’s non-U.S. Dollar denominated borrowings included €6.85 billion and ¥625.5 billion par value senior notes. The gains and losses from the periodic remeasurement of these non-U.S. Dollar denominated notes due to changes in foreign currency exchange rates are included in earnings. See Note 17 to the accompanying Consolidated Financial Statements for additional information. Parent Company debt maturities over the next five years are as follows: 2021—$2,172 million; 2022—$600 million; 2023—$4,633 million; 2024—$2,272 million and 2025—$1,801 million. The Parent Company guarantees certain debt of subsidiaries, which in the aggregate, approximated $14.4 billion at December 31, 2020 and included $13.1 billion of debt issued by Berkshire Hathaway Finance Corporation. Such guarantees are an absolute, unconditional and irrevocable guarantee for the full and prompt payment when due of all present and future payment obligations. The Parent Company has also provided guarantees in connection with equity index put option contracts and certain retroactive reinsurance contracts issued by subsidiaries. The amounts of subsidiary payments under these contracts, if any, is contingent upon the outcome of future events.

Significant accounting polici_2

Significant accounting policies and practices (Policies)	12 Months Ended
	Dec. 31, 2020
Nature of operations and basis of consolidation	(a) Nature of operations and basis of consolidation Berkshire Hathaway Inc. (“Berkshire”) is a holding company owning subsidiaries engaged in a number of diverse business activities, including insurance and reinsurance, freight rail transportation, utilities and energy, manufacturing, service and retailing. In these notes the terms “us,” “we,” or “our” refer to Berkshire and its consolidated subsidiaries. Further information regarding our reportable business segments is contained in Note 27. Information concerning business acquisitions completed over the past three years appears in Note 2. We believe that reporting the Railroad, Utilities and Energy subsidiaries separately is appropriate given the relative significance of their long-lived assets, capital expenditures and debt, which is not guaranteed by Berkshire. The accompanying Consolidated Financial Statements include the accounts of Berkshire consolidated with the accounts of all subsidiaries and affiliates in which we hold a controlling financial interest as of the financial statement date. Normally a controlling financial interest reflects ownership of a majority of the voting interests. We consolidate variable interest entities (“VIE”) when we possess both the power to direct the activities of the VIE that most significantly affect its economic performance, and we (a) are obligated to absorb the losses that could be significant to the VIE or (b) hold the right to receive benefits from the VIE that could be significant to the VIE. Intercompany accounts and transactions have been eliminated.
Use of estimates in preparation of financial statements	(b) Use of estimates in preparation of financial statements We prepare our Consolidated Financial Statements in conformity with accounting principles generally accepted in the United States (“GAAP”) which requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities at the balance sheet date and the reported amounts of revenues and expenses during the period. Our estimates of unpaid losses and loss adjustment expenses are subject to considerable estimation error due to the inherent uncertainty in projecting ultimate claim costs. In addition, estimates and assumptions associated with the amortization of deferred charges on retroactive reinsurance contracts, determinations of fair values of certain financial instruments and evaluations of goodwill and identifiable intangible assets for impairment require considerable judgment. Actual results may differ from the estimates used in preparing our Consolidated Financial Statements. The novel coronavirus (“COVID-19”) spread rapidly across the world in 2020 and was declared a pandemic by the World Health Organization. The government and private sector responses to contain its spread began to significantly affect our operating businesses in March. COVID-19 has since adversely affected nearly all of our operations, although the effects are varying significantly. The duration and extent of the effects over longer terms cannot be reasonably estimated at this time. The risks and uncertainties resulting from the pandemic that may affect our future earnings, cash flows and financial condition include the time necessary to distribute safe and effective vaccines and to vaccinate a significant number of people in the U.S. and throughout the world as well as the long-term effect from the pandemic on the demand for certain of our products and services. Accordingly, significant estimates used in the preparation of our financial statements including those associated with evaluations of certain long-lived assets, goodwill and other intangible assets for impairment, expected credit losses on amounts owed to us and the estimations of certain losses assumed under insurance and reinsurance contracts may be subject to significant adjustments in future periods.
Cash and cash equivalents and short-term investments in U.S. Treasury Bills	(c) Cash and cash equivalents and short-term investments in U.S. Treasury Bills Cash equivalents consist of demand deposit and money market accounts and investments (including U.S. Treasury Bills) with maturities of three months or less when purchased. Short-term investments in U.S. Treasury Bills consist of U.S. Treasury Bills with maturities exceeding three months at the time of purchase and are stated at amortized cost, which approximates fair value.
Investments under the equity method	(f) Investments under the equity method We utilize the equity method to account for investments when we possess the ability to exercise significant influence, but not control, over the operating and financial policies of the investee. The ability to exercise significant influence is presumed when the investor possesses more than 20% of the voting interests of the investee. This presumption may be overcome based on specific facts and circumstances that demonstrate that the ability to exercise significant influence is restricted. We apply the equity method to investments in common stock and to other investments when such other investments possess substantially identical subordinated interests to common stock. In applying the equity method, we record the investment at cost and subsequently increase or decrease the carrying amount of the investment by our proportionate share of the net earnings or losses and other comprehensive income of the investee. We record dividends or other equity distributions as reductions in the carrying value of the investment. In the event that net losses of the investee reduce the carrying amount to zero, additional net losses may be recorded if other investments in the investee are at-risk, even if we have not committed to provide financial support to the investee. Such additional equity method losses, if any, are based upon the change in our claim on the investee’s book value.
Receivables	(g) Receivables Receivables primarily consist of balances due from customers, insurance premiums receivable and reinsurance losses recoverable. Trade receivables, insurance premium receivables and other receivables are primarily short-term in nature with stated collection terms of less than one year from the date of origination. Reinsurance recoverables are comprised of amounts ceded under reinsurance contracts or pursuant to mandatory government-sponsored insurance programs. Reinsurance recoverables relate to claims for unpaid losses and loss adjustment expenses arising from property and casualty contracts and claim benefits under life and health insurance contracts. Receivables are stated net of estimated allowances for uncollectible balances. Prior to 2020, we recorded provisions for uncollectible balances when it was probable counterparties or customers would be unable to pay all amounts due based on the contractual terms and historical loss history. As of January 1, 2020, we adopted a new accounting pronouncement that affects the measurement of allowances for credit losses. See Note 1(w). In measuring credit loss allowances, we primarily utilize credit loss history, with adjustments to reflect current or expected future economic conditions when reasonable and supportable forecasts of losses deviate from historical experience. In evaluating expected credit losses of reinsurance recoverable on unpaid losses, we review the credit quality of the counterparty and consider right-of-offset provisions within reinsurance contracts and other forms of credit enhancement including, collateral, guarantees and other available information. We charge-off receivables against the allowances after all reasonable collection efforts are exhausted.
Loans and finance receivables	(h) Loans and finance receivables Loans and finance receivables are primarily manufactured home loans, and to lesser extent, commercial loans and site-built home loans. We carry substantially all of these loans at amortized cost, net of allowances for expected credit losses, based on our ability and intent to hold such loans to maturity. Acquisition costs and loan origination and commitment costs paid or fees received along with acquisition premiums or discounts are amortized as yield adjustments over the lives of the loans. Prior to 2020, credit losses were measured when non-collection was considered probable based on the prevailing facts and circumstances. Beginning in 2020, measurements of expected credit losses include provisions for non-collection, whether the risk is probable or remote. Expected credit losses on manufactured housing installment loans are based on the net present value of future principal payments less estimated expenses related to the charge-off and foreclosure of expected uncollectible loans and include provisions for loans that are not in foreclosure. Our principal credit quality indicator is whether the loans are performing. Expected credit loss estimates consider historical default rates, collateral recovery rates, historical runoff rates, interest rates, reductions of future cash flows for modified loans and the historical time elapsed from last payment until foreclosure, among other factors. In addition, our estimates consider current conditions and reasonable and supportable forecasts. Loans are considered delinquent when payments are more than 30 days past due. We place loans over 90 days past due on nonaccrual status and accrued but uncollected interest is reversed. Subsequent collections on the loans are first applied to the principal and interest owed for the most delinquent amount. We resume interest income accrual once a loan is less than 90 days delinquent. Loans are considered non-performing when the foreclosure process has started. Once a loan is in the process of foreclosure, interest income is not recognized unless the foreclosure is cured or the loan is modified. Once a modification is complete, interest income is recognized based on the terms of the new loan. Foreclosed loans are charged off when the collateral is sold. Loans not in foreclosure are evaluated for charge-off based on individual circumstances concerning the future collectability of the loan and the condition of the collateral securing the loan.
Derivatives	(i) Derivatives We carry derivative contracts in our Consolidated Balance Sheets at fair value, net of reductions permitted under master netting agreements with counterparties. We record the changes in fair value of derivative contracts that do not qualify as hedging instruments for financial reporting purposes in earnings or, if such contracts involve our regulated utilities subsidiaries, as regulatory assets or liabilities when inclusion in regulated rates is probable.
Fair value measurements	(j) Fair value measurements As defined under GAAP, fair value is the price that would be received to sell an asset or paid to transfer a liability between market participants in the principal market or in the most advantageous market when no principal market exists. Adjustments to transaction prices or quoted market prices may be required in illiquid or disorderly markets in estimating fair value. Alternative valuation techniques may be appropriate under the circumstances to determine the value that would be received to sell an asset or paid to transfer a liability in an orderly transaction. Market participants are assumed to be independent, knowledgeable, and able and willing to transact an exchange and not acting under duress. Our nonperformance or credit risk is considered in determining the fair value of liabilities. Considerable judgment may be required in interpreting market data used to develop the estimates of fair value. Accordingly, estimates of fair value presented herein are not necessarily indicative of the amounts that could be realized in a current or future market exchange.
Inventories	(k) Inventories Inventories consist of manufactured goods, goods or products acquired for resale and homes constructed for sale. Manufactured inventory costs include materials, direct and indirect labor and factory overhead. At December 31, 2020, we used the last-in-first-out (“LIFO”) method to value approximately 35% of consolidated inventories with the remainder primarily determined under first-in-first-out and average cost methods. Non-LIFO inventories are stated at the lower of cost or net realizable value. The excess of current or replacement costs over costs determined under LIFO was approximately $1.1 billion as of December 31, 2020 and $950 million as of December 31, 2019.
Property, plant and equipment	Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (l) Property, plant and equipment We record additions to property, plant and equipment used in operations at cost, which includes asset additions, improvements and betterments. With respect to constructed assets, all materials, direct labor and contract services as well as certain indirect costs are capitalized. Indirect costs include interest over the construction period. With respect to constructed assets of our utility and energy subsidiaries that are subject to authoritative guidance for regulated operations, capitalized costs also include an allowance for funds used during construction, which represents the cost of equity funds used to finance the construction of the regulated facilities. Normal repairs and maintenance and other costs that do not improve the property, extend useful lives or otherwise do not meet capitalization criteria are charged to expense as incurred. Depreciation of assets of our regulated utilities and railroad is generally determined using group depreciation methods where rates are based on periodic depreciation studies approved by the applicable regulator. Under group depreciation, a composite rate is applied to the gross investment in a particular class of property, despite differences in the service life or salvage value of individual property units within the same class. When such assets are retired or sold, no gain or loss is recognized. Gains or losses on disposals of all other assets are recorded through earnings. We depreciate property, plant and equipment used by our other businesses to estimated salvage value primarily using the straight-line method over estimated useful lives. Ranges of estimated useful lives of depreciable assets used in our other businesses are as follows: buildings and improvements – 5 to 50 years, machinery and equipment – 3 to 25 years and furniture, fixtures and other – 3 to 15 years. Ranges of estimated useful lives of depreciable assets unique to our railroad business are as follows: track structure and other roadway – 10 to 100 years and locomotives, freight cars and other equipment – 6 to 43 years. Ranges of estimated useful lives of assets unique to our regulated utilities and energy businesses are as follows: utility generation, transmission and distribution systems – 5 to 80 years, interstate natural gas pipeline assets – 3 to 80 years and independent power plants and other assets – 3 to 40 years. We evaluate property, plant and equipment for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable or when the assets are held for sale. Upon the occurrence of a triggering event, we assess whether the estimated undiscounted cash flows expected from the use of the asset and the residual value from the ultimate disposal of the asset exceeds the carrying value. If the carrying value exceeds the estimated recoverable amounts, we reduce the carrying value to fair value and record an impairment loss in earnings, except with respect to impairment of assets of our regulated utility and energy subsidiaries where the impacts of regulation are considered in evaluating the carrying value.
Leases	(m) Leases We are party to contracts where we lease property to others (“lessor” contracts) and where we lease property from others (“lessee” contracts). We record acquisitions of and additions to equipment that we lease to others at cost. We depreciate equipment held for lease to estimated salvage value primarily using the straight-line method over estimated useful lives ranging from 3 to 35 years. We use declining balance deprecation methods for assets when the revenue-earning power of the asset is relatively greater during the earlier years of its life and maintenance and repair costs increase during the later years. We also evaluate equipment held for lease for impairment consistent with policies for property, plant and equipment. When we lease assets from others, we record right-of-use assets and lease liabilities. Right-of-use assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. In this regard, lease payments include fixed payments and variable payments that depend on an index or rate. The lease term is generally the non-cancellable lease period. Certain lease contracts contain renewal options or other terms that provide for variable payments based on performance or usage. Options are not included in determining right-of-use assets or lease liabilities unless it is reasonably certain that options will be exercised. Generally, incremental borrowing rates are used in measuring lease liabilities. Right-of-use assets are subject to review for impairment.
Goodwill and other intangible assets	Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (n) Goodwill and other intangible assets Goodwill represents the excess of the acquisition price of a business over the fair value of identified net assets of that business. We evaluate goodwill for impairment at least annually. When evaluating goodwill for impairment, we estimate the fair value of the reporting unit. Several methods may be used to estimate a reporting unit’s fair value, including market quotations, asset and liability fair values and other valuation techniques, including, but not limited to, discounted projected future net earnings or net cash flows and multiples of earnings. If the carrying amount of a reporting unit, including goodwill, exceeds the estimated fair value, then the excess is charged to earnings as an impairment loss. Intangible assets with indefinite lives are also tested for impairment at least annually and when events or changes in circumstances indicate that, more-likely-than-not, the asset is impaired. Significant judgment is required in estimating fair values and performing goodwill and indefinite-life intangible asset impairment tests. We amortize intangible assets with finite lives in a pattern that reflects the expected consumption of related economic benefits or on a straight-line basis over the estimated economic useful lives. Intangible assets with finite lives are reviewed for impairment when events or changes in circumstances indicate that the carrying amount may not be recoverable.
Revenue recognition	(o) Revenue recognition We earn insurance premiums on prospective property/casualty insurance and reinsurance contracts over the loss exposure or coverage period in proportion to the level of protection provided. In most cases, such premiums are earned ratably over the term of the contract with unearned premiums computed on a monthly or daily pro-rata basis. Premiums on retroactive property/casualty reinsurance contracts are earned at the inception of the contracts, as all underlying loss events covered by the policies occurred prior to contract inception. Premiums for life reinsurance and annuity contracts are earned when due. Premiums earned are stated net of amounts ceded to reinsurers. Premiums earned on contracts with experience-rating provisions reflect estimated loss experience under such contracts. Sales and service revenues are recognized when goods or services are transferred to a customer. A good or service is transferred when (or as) the customer obtains control of that good or service. Revenues are based on the consideration we expect to receive in connection with our promises to deliver goods and services to our customers. We manufacture and/or distribute a wide variety of industrial, building and consumer products. Our sales contracts provide customers with these products through wholesale and retail channels in exchange for consideration specified under the contracts. Contracts generally represent customer orders for individual products at stated prices. Sales contracts may contain either single or multiple performance obligations. In instances where contracts contain multiple performance obligations, we allocate the revenue to each obligation based on the relative stand-alone selling prices of each product or service. Sales revenue reflects reductions for returns, allowances, volume discounts and other incentives, some of which may be contingent on future events. In certain customer contracts, sales revenue includes certain state and local excise taxes billed to customers on specified products when those taxes are levied directly upon us by the taxing authorities. Sales revenue excludes sales taxes and value-added taxes collected on behalf of taxing authorities. Sales revenue includes consideration for shipping and other fulfillment activities performed prior to the customer obtaining control of the goods. We also elect to treat consideration for such services performed after control has passed to the customer as sales revenue. Our product sales revenues are generally recognized at a point in time when control of the product transfers to the customer, which coincides with customer pickup or product delivery or acceptance, depending on terms of the arrangement. We recognize sales revenues and related costs with respect to certain contracts over time, primarily from certain castings, forgings and aerostructures contracts. Control of the product units under these contracts transfers continuously to the customer as the product is manufactured. These products generally have no alternative use and the contract requires the customer to provide reasonable compensation if terminated for reasons other than breach of contract. Notes to Consolidated Financial Statements (Continued) (1) Significant accounting policies and practices (Continued) (o) Revenue recognition (Continued) Our energy revenue derives primarily from tariff-based sales arrangements approved by various regulatory commissions. These tariff-based revenues are mainly comprised of energy, transmission, distribution and natural gas and have performance obligations to deliver energy products and services to customers which are satisfied over time as energy is delivered or services are provided. Our nonregulated energy revenue primarily relates to our renewable energy business. Energy revenues are equivalent to the amounts we have the right to invoice and correspond directly with the value to the customer of the performance to date and include billed and unbilled amounts. Payments from customers are generally due within 30 days of billing. Rates charged for energy products and services are established by regulators or contractual arrangements that establish the transaction price, as well as the allocation of price among the separate performance obligations. When preliminary regulated rates are permitted to be billed prior to final approval by the applicable regulator, certain revenue collected may be subject to refund and a liability for estimated refunds is accrued. The primary performance obligation under our freight rail transportation service contracts is to move freight from a point of origin to a point of destination. The performance obligations are represented by bills of lading which create a series of distinct services that have a similar pattern of transfer to the customer. The revenues for each performance obligation are based on various factors including the product being shipped, the origin and destination pair and contract incentives, which are outlined in various private rate agreements, common carrier public tariffs, interline foreign road agreements and pricing quotes. The transaction price is generally a per car/unit amount to transport railcars from a specified origin to a specified destination. Freight revenues are recognized over time as the service is performed because the customer simultaneously receives and consumes the benefits of the service. Revenues recognized represent the proportion of the service completed as of the balance sheet date. Invoices for freight transportation services are generally issued to customers and paid within 30 days or less. Customer incentives, which are primarily provided for shipping a specified cumulative volume or shipping to/from specific locations, are recorded as a reduction to revenue on a pro-rata basis based on actual or projected future customer shipments. Other service revenues derive from contracts with customers in which performance obligations are satisfied over time, where customers receive and consume benefits as we perform the services, or at a point in time when the services are provided. Other service revenues primarily derive from real estate brokerage, automotive repair, aircraft management, aviation training and franchising and news distribution services. Leasing revenue is generally recognized ratably over the term of the lease or based on usage, if applicable under the terms of the contract. A substantial portion of our leases are classified as operating leases.
Losses and loss adjustment expenses	(p) Losses and loss adjustment expenses We record liabilities for unpaid losses and loss adjustment expenses under property/casualty insurance and reinsurance contracts for loss events that have occurred on or before the balance sheet date. Such liabilities represent the estimated ultimate payment amounts without discounting for time value. We base liability estimates on (1) loss reports from policyholders and cedents, (2) individual case estimates and (3) estimates of incurred but not reported losses. Losses and loss adjustment expenses in the Consolidated Statements of Earnings include paid claims, claim settlement costs and changes in estimated claim liabilities. Losses and loss adjustment expenses charged to earnings are net of amounts recovered and estimates of amounts recoverable under ceded reinsurance contracts. Reinsurance contracts do not relieve the ceding company of its obligations to indemnify policyholders with respect to the underlying insurance and reinsurance contracts.
Retroactive reinsurance contracts	(q) Retroactive reinsurance contracts We record liabilities for unpaid losses and loss adjustment expenses under short duration retroactive reinsurance contracts consistent with other short duration property/casualty insurance and reinsurance contracts described in Note 1(p). With respect to retroactive reinsurance contracts, we also record deferred charge assets at the inception of the contracts, representing the excess, if any, of the estimated ultimate claim liabilities over the premiums earned. We subsequently amortize the deferred charge assets over the expected claim settlement periods using the interest method. Changes to the estimated timing or amount of future loss payments also produce changes in deferred charge balances. We apply changes in such estimates retrospectively and the resulting changes in deferred charge balances, together with periodic amortization, are included in insurance losses and loss adjustment expenses in the Consolidated Statements of Earnings.
Insurance policy acquisition costs	(r) Insurance policy acquisition costs We capitalize the incremental costs that directly relate to the successful sale of insurance contracts, subject to ultimate recoverability, and we subsequently amortize such costs to underwriting expenses as the related premiums are earned. Direct incremental acquisition costs include commissions, premium taxes and certain other costs associated with successful efforts. We expense all other underwriting costs as incurred. The recoverability of capitalized insurance policy acquisition costs generally reflects anticipation of investment income. The unamortized balances are included in other assets and were approximately $3.25 billion and $2.95 billion at December 31, 2020 and 2019, respectively.
Life and annuity insurance benefits	(s) Life and annuity insurance benefits We compute liabilities for insurance benefits under life contracts based upon estimated future investment yields, expected mortality, morbidity and lapse or withdrawal rates, as well as estimates of premiums we expect to receive and expenses we expect to incur in the future. These assumptions, as applicable, also include a margin for adverse deviation and may vary with the characteristics of the contract’s date of issuance, policy duration and country of risk. The interest rate assumptions used may vary by contract or jurisdiction. We discount periodic payment annuity liabilities based on the implicit rate as of the inception of the contracts such that the present value of the liabilities equals the premiums. Discount rates for most contracts range from 3% to 7%.
Regulated utilities and energy businesses	(t) Regulated utilities and energy businesses Certain energy subsidiaries prepare their financial statements in accordance with authoritative guidance for regulated operations, reflecting the economic effects of regulation from the ability to recover certain costs from customers and the requirement to return revenues to customers in the future through the regulated rate-setting process. Accordingly, certain costs are deferred as regulatory assets and certain income is accrued as regulatory liabilities. Regulatory assets and liabilities will be amortized into operating expenses and revenues over various future periods. Regulatory assets and liabilities are continually assessed for probable future inclusion in regulatory rates by considering factors such as applicable regulatory or legislative changes and recent rate orders received by other regulated entities. If future inclusion in regulatory rates ceases to be probable, the amount no longer probable of inclusion in regulatory rates is charged or credited to earnings (or other comprehensive income, if applicable) or returned to customers.
Foreign currency	(u) Foreign currency The accounts of our non-U.S. based subsidiaries are measured, in most instances, using functional currencies other than the U.S. Dollar. Revenues and expenses in the financial statements of these subsidiaries are translated into U.S. Dollars at the average exchange rate for the period and assets and liabilities are translated at the exchange rate as of the end of the reporting period. The net effects of translating the financial statements of these subsidiaries are included in shareholders’ equity as a component of accumulated other comprehensive income. Gains and losses arising from transactions denominated in a currency other than the functional currency of the reporting entity, including gains and losses from the remeasurement of assets and liabilities due to changes in currency exchange rates, are included in earnings.
Income taxes	(v) Income taxes Berkshire files a consolidated federal income tax return in the United States, which includes eligible subsidiaries. In addition, we file income tax returns in state, local and foreign jurisdictions as applicable. Provisions for current income tax liabilities are calculated and accrued on income and expense amounts expected to be included in the income tax returns for the current year. Income taxes reported in earnings also include deferred income tax provisions. Deferred income tax assets and liabilities are computed on differences between the financial statement bases and tax bases of assets and liabilities at the enacted tax rates. Changes in deferred income tax assets and liabilities associated with components of other comprehensive income are charged or credited directly to other comprehensive income. Otherwise, changes in deferred income tax assets and liabilities are included as a component of income tax expense. The effect on deferred income tax assets and liabilities attributable to changes in enacted tax rates are charged or credited to income tax expense in the period of enactment. Valuation allowances are established for certain deferred tax assets when realization is not likely. Assets and liabilities are established for uncertain tax positions taken or positions expected to be taken in income tax returns when such positions, in our judgment, do not meet a more-likely-than-not threshold based on the technical merits of the positions. Estimated interest and penalties related to uncertain tax positions are included as a component of income tax expense.
New accounting pronouncements adopted	(w) New accounting pronouncements adopted in 2020 We adopted Accounting Standards Codification (“ASC”) 326 “Financial Instruments-Credit Losses” on January 1, 2020. ASC 326 provides for the measurement of expected credit losses on financial assets that are carried at amortized cost based on the net amounts expected to be collected. Measurements of expected credit losses therefore include provisions for non-collection, whether the risk is probable or remote. Prior to the adoption of ASC 326, credit losses were measured when non-collection was considered probable based on the prevailing facts and circumstances. We do not measure an allowance for expected credit losses on accrued interest and instead, as permitted, we elected to reverse uncollectible accrued interest through interest income on a timely basis. Upon adoption of ASC 326, we recorded a charge to retained earnings of $388 million representing the cumulative after-tax increase in our allowances for credit losses, which was primarily related to our manufactured housing loans. ( x ) New accounting pronouncements adopted in 2019 Berkshire adopted ASC 842 “Leases” on January 1, 2019. Most significantly, ASC 842 requires a lessee to recognize a liability to make operating lease payments and an asset with respect to its right to use the underlying asset for the lease term. In adopting and applying ASC 842, we elected to use practical expedients, including but not limited to, not reassessing past lease and easement accounting, not separating lease components from non-lease components by class of asset and not recording assets or liabilities for leases with terms of one year or less. We adopted ASC 842 as of January 1, 2019 with respect to contracts in effect as of that date and elected to not restate prior period financial statements. Upon the adoption of ASC 842, we recognized operating lease right-of-use assets of approximately $6.2 billion and lease liabilities of $5.9 billion. We also reduced other assets by approximately $300 million. Consequently, our consolidated assets and liabilities increased by approximately $5.9 billion. ASC 842 did not have a material effect on our accounting for our lessor contracts or for lessee contracts classified as financing leases. ( y ) New accounting pronouncements adopted in 2018 On January 1, 2018, we adopted Accounting Standards Update (“ASU”) 2016-01 “Financial Instruments—Recognition and Measurement of Financial Assets and Financial Liabilities,” ASU 2018-02 “Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” and ASC 606 “Revenues from Contracts with Customers.” Prior year financial statements were not restated. A summary of the effects of the initial adoption of ASU 2016-01, ASU 2018-02 and ASC 606 on our shareholders’ equity follows (in millions). ASU 2016-01 ASU 2018-02 ASC 606 Total Increase (decrease): Accumulated other comprehensive income $ (61,459 ) $ 84 $ — $ (61,375 ) Retained earnings 61,459 (84 ) (70 ) 61,305 Shareholders’ equity — — (70 ) (70 ) In adopting ASU 2016-01, as of January 1, 2018, we reclassified the net after-tax unrealized gains on equity securities from accumulated other comprehensive income to retained earnings. Thereafter, the unrealized gains and losses from the changes during the period in the fair values of our equity securities are included within investment gains/losses in the Consolidated Statements of Earnings. In adopting ASU 2018-02, we reclassified certain deferred income tax effects as of January 1, 2018 attributable to the reduction in the U.S. statutory income tax rate under the Tax Cuts and Jobs Act of 2017 from accumulated other comprehensive income to retained earnings. In adopting ASC 606, we recorded increases to certain assets and other liabilities, with the cumulative net effect recorded to retained earnings.
New accounting pronouncements to be adopted subsequent to December 31, 2020	( z ) New accounting pronouncements to be adopted subsequent to December 31, 2020 In August 2018, the FASB issued ASU 2018-12 “Targeted Improvements to the Accounting for Long-Duration Contracts.” ASU 2018-12 requires periodic reassessment of actuarial and discount rate assumptions used to value policyholder liabilities and deferred acquisition costs of long-duration insurance and reinsurance contracts, with the effects of changes in cash flow assumptions reflected in earnings and the effects of changes in discount rate assumptions reflected in other comprehensive income. Under current GAAP, the actuarial and discount rate assumptions are set at the contract inception date and not subsequently changed, except under limited circumstances. ASU 2018-12 requires new disclosures and is effective for fiscal years beginning after December 15, 2022, with early adoption permitted. We are evaluating the effect this standard will have on our Consolidated Financial Statements.
Fixed Maturities [Member]
Investments in fixed maturity and equity securities	(d) Investments in fixed maturity securities We classify investments in fixed maturity securities on the acquisition date and at each balance sheet date. Securities classified as held-to-maturity are carried at amortized cost, reflecting the ability and intent to hold the securities to maturity. Securities classified as trading are acquired with the intent to sell in the near term and are carried at fair value with changes in fair value reported in earnings. All other securities are classified as available-for-sale and are carried at fair value. Substantially all of these investments are classified as available-for-sale. We amortize the difference between the original cost and maturity value of a fixed maturity security to earnings using the interest method. We record investment gains and losses on available-for-sale fixed maturity securities when the securities are sold, as determined on a specific identification basis. For securities in an unrealized loss position, we recognize a loss in earnings for the excess of amortized cost over fair value if we intend to sell before the price recovers. Otherwise, we evaluate as of the balance sheet date whether the unrealized losses are attributable to credit losses or other factors. We consider the severity of the decline in value, creditworthiness of the issuer and other relevant factors. We record an allowance for credit losses, limited to the excess of amortized cost over fair value, along with a corresponding charge to earnings if the present value of estimated cash flows is less than the present value of contractual cash flows. The allowance may be subsequently increased or decreased based on the prevailing facts and circumstances. The portion of the unrealized loss that we believe is not related to a credit loss is recognized in other comprehensive income.
Equity Securities [Member]
Investments in fixed maturity and equity securities	(e) Investments in equity securities We carry substantially all investments in equity securities at fair value and record the subsequent changes in fair values in the Consolidated Statements of Earnings as a component of investment gains/losses.

Significant accounting polici_3

Significant accounting policies and practices (Tables)	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of effects of initial adoption of ASU 2016-01, ASU 2018-02 and ASC 606	A summary of the effects of the initial adoption of ASU 2016-01, ASU 2018-02 and ASC 606 on our shareholders’ equity follows (in millions). ASU 2016-01 ASU 2018-02 ASC 606 Total Increase (decrease): Accumulated other comprehensive income $ (61,459 ) $ 84 $ — $ (61,375 ) Retained earnings 61,459 (84 ) (70 ) 61,305 Shareholders’ equity — — (70 ) (70 )

Business acquisitions (Tables)

Business acquisitions (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Summary of preliminary fair values of identified assets acquired and liabilities assumed and residual goodwill	The cost of the acquisition completed on November 1, 2020, was approximately $2.5 billion after post-closing adjustments as provided in the agreement. The preliminary fair values of identified assets acquired and liabilities assumed and residual goodwill are summarized as follows (in millions). Property, plant and equipment $ 9,254 Goodwill 1,732 Other 2,376 Assets acquired $ 13,362 Notes payable and other borrowings $ 5,615 Other 1,317 Liabilities assumed 6,932 Noncontrolling interests 3,916 Net assets $ 2,514

Investments in fixed maturity_2

Investments in fixed maturity securities (Tables)	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Schedule of investments in securities with fixed maturities	Investments in fixed maturity securities as of December 31, 2020 and 2019 are summarized by type below (in millions). Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2020 U.S. Treasury, U.S. government corporations and agencies $ 3,348 $ 55 $ — $ 3,403 Foreign governments 11,233 110 (5 ) 11,338 Corporate bonds 4,729 464 (2 ) 5,191 Other 414 66 (2 ) 478 $ 19,724 $ 695 $ (9 ) $ 20,410 December 31, 2019 U.S. Treasury, U.S. government corporations and agencies $ 3,054 $ 37 $ (1 ) $ 3,090 Foreign governments 8,584 63 (9 ) 8,638 Corporate bonds 5,896 459 (3 ) 6,352 Other 539 67 (1 ) 605 $ 18,073 $ 626 $ (14 ) $ 18,685
Schedule of amortized cost and estimated fair value of securities with fixed maturities	The amortized cost and estimated fair value of fixed maturity securities at December 31, 2020 are summarized below by contractual maturity dates. Amounts are in millions. Actual maturities may differ from contractual maturities due to early call or prepayment rights held by issuers. Due in one year or less Due after one year through five years Due after five years through ten years Due after ten years Mortgage-backed securities Total Amortized cost $ 10,379 $ 8,323 $ 373 $ 337 $ 312 $ 19,724 Fair value 10,448 8,456 496 640 370 20,410

Investments in equity securit_2

Investments in equity securities (Tables)	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Schedule of investments in equity securities	Investments in equity securities as of December 31, 2020 and 2019 are summarized based on the primary industry of the investee in the table below (in millions). Cost Basis Net Unrealized Gains Fair Value December 31, 2020 * Banks, insurance and finance $ 26,312 $ 40,167 $ 66,479 Consumer products 34,747 111,583 146,330 Commercial, industrial and other 47,561 20,800 68,361 $ 108,620 $ 172,550 $ 281,170 * Approximately 68% of the aggregate fair value was concentrated in four companies (American Express Company – $18.3 billion; Apple Inc. – $120.4 billion; Bank of America Corporation – $31.3 billion and The Coca-Cola Company – $21.9 billion). Cost Basis Net Unrealized Gains Fair Value December 31, 2019 * Banks, insurance and finance $ 40,419 $ 61,976 $ 102,395 Consumer products 38,887 60,747 99,634 Commercial, industrial and other 31,034 14,964 45,998 $ 110,340 $ 137,687 $ 248,027 * Approximately 60% of the aggregate fair value was concentrated in four companies (American Express Company – $18.9 billion; Apple Inc. – $73.7 billion; Bank of America Corporation – $33.4 billion and The Coca-Cola Company – $22.1 billion).

Equity method investments (Tabl

Equity method investments (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments And Joint Ventures [Abstract]
Summarized financial information of Kraft Heinz	Summarized financial information of Kraft Heinz follows (in millions). December 26, 2020 December 28, 2019 Assets $ 99,830 $ 101,450 Liabilities 49,587 49,701 Year ending December 26, 2020 Year ending December 28, 2019 Year ending December 29, 2018 Sales $ 26,185 $ 24,977 $ 26,268 Net earnings (losses) attributable to Kraft Heinz common shareholders $ 356 $ 1,935 $ (10,192 )

Investment gains_losses (Tables

Investment gains/losses (Tables)	12 Months Ended
	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Summary of investment gains and losses	Investment gains/losses for each of the three years ending December 31, 2020 are summarized below (in millions). 2020 2019 2018 Equity securities: Change in unrealized investment gains/losses during the year on securities held at the end of the period $ 54,951 $ 69,581 $ (22,729 ) Investment gains/losses during the year on securities sold (14,036 ) 1,585 291 40,915 71,166 (22,438 ) Fixed maturity securities: Gross realized gains 56 87 480 Gross realized losses (27 ) (25 ) (227 ) Other (39 ) (105 ) 30 $ 40,905 $ 71,123 $ (22,155 )

Loans and finance receivables (

Loans and finance receivables (Tables)	12 Months Ended
	Dec. 31, 2020
Loans and Finance Receivables [Member]
Schedule of receivables	Loans and finance receivables are summarized as follows (in millions). December 31, 2020 2019 Loans and finance receivables before allowances and discounts $ 20,436 $ 18,199 Allowances for uncollectible loans (712 ) (167 ) Unamortized acquisition discounts and points (523 ) (505 ) $ 19,201 $ 17,527
Schedule of reconciliation of allowance for credit losses on loans and finance receivables	Loans and finance receivables are principally manufactured home loans, and to a lesser extent, commercial loans and site-built home loans. Reconciliations of the allowance for credit losses on loans and finance receivables for 2020 and 2019 follow (in millions). 2020 2019 Balance at beginning of year $ 167 $ 177 Adoption of ASC 326 486 — Provision for credit losses 177 125 Charge-offs, net of recoveries (118 ) (135 ) Balance at December 31 $ 712 $ 167
Manufactured Housing Loan Balances [Member]
Summary of performing and non-performing home loans before discounts and allowances by year of loan origination	A summary of performing and non-performing home loans before discounts and allowances by year of loan origination as of December 31, 2020 follows (in millions). Loans and Financing Receivables by Origination Year 2020 2019 2018 2017 2016 Prior Total Performing $ 4,430 $ 2,537 $ 1,928 $ 1,424 $ 1,276 $ 6,645 $ 18,240 Non-performing 3 5 7 7 7 43 72 Total $ 4,433 $ 2,542 $ 1,935 $ 1,431 $ 1,283 $ 6,688 $ 18,312

Other receivables (Tables)

Other receivables (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance and Other [Member]
Schedule of receivables	Other receivables of insurance and other businesses are comprised of the following (in millions). December 31, 2020 2019 Insurance premiums receivable $ 14,025 $ 13,379 Reinsurance recoverables 4,805 4,470 Trade receivables 11,521 12,275 Other 2,637 2,712 Allowances for uncollectible accounts (678 ) (418 ) $ 32,310 $ 32,418
Railroad, Utilities and Energy [Member]
Schedule of receivables	Receivables of our railroad and utilities and energy businesses are comprised of the following (in millions). December 31, 2020 2019 Trade receivables $ 3,235 $ 3,120 Other 438 388 Allowances for uncollectible accounts (131 ) (91 ) $ 3,542 $ 3,417

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Schedule of inventories	Inventories are comprised of the following (in millions). December 31, 2020 2019 Raw materials $ 4,821 $ 4,492 Work in process and other 2,541 2,700 Finished manufactured goods 4,412 4,821 Goods acquired for resale 7,434 7,839 $ 19,208 $ 19,852

Property, plant and equipment_2

Property, plant and equipment including equipment held for lease (Tables)	12 Months Ended
	Dec. 31, 2020
Schedule of depreciation expense	Depreciation expense for each of the three years ending December 31, 2020 is summarized below (in millions). 2020 2019 2018 Insurance and other $ 2,320 $ 2,269 $ 2,186 Railroad, utilities and energy 5,799 5,297 5,098 $ 8,119 $ 7,566 $ 7,284
Insurance and Other [Member]
Schedule of property, plant and equipment	A summary of property, plant and equipment of our insurance and other businesses follows (in millions). December 31, 2020 2019 Land, buildings and improvements $ 13,799 $ 13,259 Machinery and equipment 25,488 24,285 Furniture, fixtures and other 4,530 4,666 43,817 42,210 Accumulated depreciation (22,617 ) (20,772 ) $ 21,200 $ 21,438
Railroad, Utilities and Energy [Member]
Schedule of property, plant and equipment	A summary of property, plant and equipment of railroad and utilities and energy businesses follows (in millions). The utility generation, transmission and distribution systems and interstate natural gas pipeline assets are owned by regulated public utility and natural gas pipeline subsidiaries. December 31, 2020 2019 Railroad: Land, track structure and other roadway $ 63,824 $ 62,404 Locomotives, freight cars and other equipment 13,523 13,482 Construction in progress 916 748 78,263 76,634 Accumulated depreciation (13,175 ) (12,101 ) 65,088 64,533 Utilities and energy: Utility generation, transmission and distribution systems 86,730 81,127 Interstate natural gas pipeline assets 16,667 8,165 Independent power plants and other assets 12,671 8,817 Construction in progress 3,308 3,732 119,376 101,841 Accumulated depreciation (33,248 ) (28,536 ) 86,128 73,305 $ 151,216 $ 137,838

Equipment held for lease (Table

Equipment held for lease (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Schedule of equipment held for lease	Equipment held for lease includes railcars, aircraft, over-the-road trailers, intermodal tank containers, cranes, storage units and furniture. Equipment held for lease is summarized below (in millions). December 31, 2020 2019 Railcars $ 9,402 $ 9,260 Aircraft 8,204 8,093 Other 4,868 4,862 22,474 22,215 Accumulated depreciation (7,873 ) (7,150 ) $ 14,601 $ 15,065
Summary of fixed and variable operating lease revenues	Fixed and variable operating lease revenues for each of the two years ending December 31, 2020 are summarized below (in millions). 2020 2019 Fixed lease revenue $ 4,262 $ 4,415 Variable lease revenue 947 1,441 $ 5,209 $ 5,856
Summary of remaining operating lease receipts	A summary of future operating lease receipts as of December 31, 2020 follows (in millions). 2021 2022 2023 2024 2025 Thereafter Total $ 2,618 $ 1,962 $ 1,429 $ 905 $ 443 $ 387 $ 7,744

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Summary of remaining operating lease payments	A summary of our remaining operating lease payments as of December 31, 2020 and December 31, 2019 follows (in millions). Year 1 Year 2 Year 3 Year 4 Year 5 Thereafter Total lease payments Amount representing interest Lease liabilities December 31: 2020 $ 1,342 $ 1,111 $ 905 $ 725 $ 544 $ 1,691 $ 6,318 $ (849 ) $ 5,469 2019 1,374 1,183 950 764 620 1,988 6,879 (997 ) 5,882
Components of operating lease costs	Components of operating lease costs for the years ending December 31, 2020 and 2019, by type, are summarized in the following table (in millions). 2020 2019 Operating lease cost $ 1,413 $ 1,459 Short-term lease cost 145 178 Variable lease cost 228 276 Sublease income (10 ) (24 ) Total lease cost $ 1,776 $ 1,889

Goodwill and other intangible_2

Goodwill and other intangible assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Reconciliation of the change in goodwill	Reconciliations of the changes in the carrying value of goodwill during 2020 and 2019 follows (in millions). December 31, 2020 2019 Balance at beginning of year $ 81,882 $ 81,025 Acquisitions of businesses 1,758 890 Impairment charges (10,033 ) (90 ) Other, including foreign currency translation 127 57 Balance at end of year* $ 73,734 $ 81,882 * Net of accumulated goodwill impairments of $11.0 billion as of December 31, 2020 and $1.1 billion as of December 31, 2019.
Schedule of intangible assets	The gross carrying amounts and related accumulated amortization of other intangible assets are summarized as follows (in millions). December 31, 2020 December 31, 2019 Gross carrying amount Accumulated amortization Gross carrying amount Accumulated amortization Insurance and other: Customer relationships $ 27,374 $ 5,756 $ 27,943 $ 5,025 Trademarks and trade names 5,206 779 5,286 759 Patents and technology 4,766 3,313 4,560 3,032 Other 3,339 1,375 3,364 1,286 $ 40,685 $ 11,223 $ 41,153 $ 10,102 Railroad, utilities and energy: Customer relationships $ 678 $ 361 $ 678 $ 324 Trademarks, trade names and other 1,003 98 325 84 $ 1,681 $ 459 $ 1,003 $ 408

Derivative contracts (Tables)

Derivative contracts (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative contracts outstanding	Information related to these contracts follows (dollars in millions). December 31, 2020 2019 Balance sheet liabilities - at fair value $ 1,065 $ 968 Notional value 10,991 14,385 Intrinsic value 727 397 Weighted average remaining life (in years) 1.2 1.8

Unpaid losses and loss adjust_2

Unpaid losses and loss adjustment expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Schedule of liability for unpaid claims and claims adjustment expense	A reconciliation of the changes in claim liabilities, excluding liabilities under retroactive reinsurance contracts (see Note 16), for each of the three years ending December 31, 2020 is as follows (in millions). 2020 2019 2018 Balances at beginning of year: Gross liabilities $ 73,019 $ 68,458 $ 61,122 Reinsurance recoverable on unpaid losses (2,855 ) (3,060 ) (3,201 ) Net liabilities 70,164 65,398 57,921 Incurred losses and loss adjustment expenses: Current accident year events 43,400 43,335 39,876 Prior accident years’ events (356 ) (752 ) (1,406 ) Total 43,044 42,583 38,470 Paid losses and loss adjustment expenses: Current accident year events (17,884 ) (19,482 ) (18,391 ) Prior accident years’ events (18,862 ) (17,642 ) (15,452 ) Total (36,746 ) (37,124 ) (33,843 ) Foreign currency translation adjustment 480 (23 ) (331 ) Business acquisition (disposition) — (670 ) 3,181 Balances at December 31: Net liabilities 76,942 70,164 65,398 Reinsurance recoverable on unpaid losses 2,912 2,855 3,060 Gross liabilities $ 79,854 $ 73,019 $ 68,458
Schedule of reconciliation of unpaid losses and allocated loss adjustment expenses to balance sheet liability	A reconciliation of the disaggregated net unpaid losses and allocated loss adjustment expenses (the latter referred to as “ALAE”) of GEICO, Berkshire Hathaway Primary Group (“BH Primary”) and Berkshire Hathaway Reinsurance Group (“BHRG”) to our consolidated unpaid losses and loss adjustment expenses as of December 31, 2020 follows (in millions). GEICO Physical Damage GEICO Auto Liability BH Primary Medical Professional Liability BH Primary Workers’ Compensation and Other Casualty BHRG Property BHRG Casualty Total Unpaid losses and ALAE, net $ 524 $ 18,755 $ 7,897 $ 11,294 $ 11,280 $ 22,890 $ 72,640 Reinsurance recoverable — 1,109 49 621 181 864 2,824 Unpaid unallocated loss adjustment expenses 2,671 Other unpaid losses and loss adjustment expenses 1,719 Unpaid losses and loss adjustment expenses $ 79,854
Schedule of average historical claims duration	Required supplemental unaudited average historical claims duration information based on the net losses and ALAE incurred and paid accident year data in the preceding tables follows. The percentages show the average portions of net losses and ALAE paid by each succeeding year, with year 1 representing the current accident year. Average Annual Percentage Payout of Incurred Losses by Age, Net of Reinsurance In Year 1 2 3 4 5 6 7 8 9 10 GEICO Physical Damage 97 % 2 % GEICO Auto Liability 42 % 29 % 13 % 7 % 4 % BH Primary Medical Professional Liability 2 % 7 % 12 % 14 % 14 % 12 % 9 % 6 % 5 % 2 % BH Primary Workers’ Compensation and Other Casualty 16 % 21 % 16 % 13 % 8 % 4 % 3 % 2 % 1 % 1 % BHRG Property 19 % 37 % 17 % 8 % 4 % 4 % 1 % 2 % 1 % 0 % BHRG Casualty 11 % 16 % 14 % 9 % 5 % 5 % 5 % 2 % 2 % 1 %
GEICO [Member] | Insurance Group [Member] | Physical Damage [Member]
Schedule of incurred and paid losses and allocated loss adjustment expenses	GEICO’s incurred and paid losses and ALAE, net of reinsurance, are summarized by accident year below for physical damage and auto liability claims. IBNR and case development liabilities are as of December 31, 2020. Claim counts are established when accidents that may result in a liability are reported and are based on policy coverage. Each claim event may generate claims under multiple coverages, and thus may result in multiple counts. The “Cumulative Number of Reported Claims” includes the combined number of reported claims for all policy coverages and excludes projected IBNR claims. Dollars are in millions. Physical Damage Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2019 $ 9,020 $ 8,920 $ 69 8,929 2020 8,603 296 7,794 Incurred losses and ALAE $ 17,523 Cumulative Paid Losses and ALAE through December 31, Accident Year 2019* 2020 2019 $ 8,678 $ 8,905 2020 8,118 Paid losses and ALAE 17,023 Net unpaid losses and ALAE for 2019 – 2020 accident years 500 Net unpaid losses and ALAE for accident years before 2019 24 Net unpaid losses and ALAE $ 524
GEICO [Member] | Insurance Group [Member] | Auto Liability [Member]
Schedule of incurred and paid losses and allocated loss adjustment expenses	Auto Liability Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2016 $ 11,800 $ 12,184 $ 12,149 $ 12,178 $ 12,198 $ 222 2,451 2017 14,095 13,864 13,888 13,824 502 2,639 2018 15,383 15,226 14,985 1,163 2,702 2019 16,901 16,678 2,905 2,749 2020 14,637 4,482 1,945 Incurred losses and ALAE $ 72,322 Cumulative Paid Losses and ALAE through December 31, Accident Year 2016* 2017* 2018* 2019* 2020 2016 $ 5,069 $ 8,716 $ 10,330 $ 11,294 $ 11,718 2017 5,806 9,944 11,799 12,729 2018 6,218 10,772 12,658 2019 6,742 11,671 2020 5,395 Paid losses and ALAE 54,171 Net unpaid losses and ALAE for 2016 – 2020 accident years 18,151 Net unpaid losses and ALAE for accident years before 2016 604 Net unpaid losses and ALAE $ 18,755 * Unaudited required supplemental information
Berkshire Hathaway Primary Group [Member] | Insurance Group [Member] | Medical Professional Liability [Member]
Schedule of incurred and paid losses and allocated loss adjustment expenses	BH Primary Medical Professional Liability We estimate the ultimate expected incurred losses and loss adjustment expenses for medical professional claim liabilities using a variety of commonly accepted actuarial methodologies, such as the paid and incurred development method and Bornhuetter-Ferguson based methods, as well as other techniques that consider insured loss exposures and historical and expected loss trends, among other factors. These methodologies produce loss estimates from which we determine our best estimate. In addition, we study developments in older accident years and adjust initial loss estimates to reflect recent development based upon claim age, coverage and litigation experience. Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2011 $ 1,346 $ 1,334 $ 1,321 $ 1,262 $ 1,173 $ 1,115 $ 1,050 $ 1,004 $ 968 $ 972 $ 39 11 2012 1,336 1,306 1,277 1,223 1,168 1,078 1,035 998 988 53 11 2013 1,328 1,296 1,261 1,195 1,127 1,086 1,019 985 65 11 2014 1,370 1,375 1,305 1,246 1,218 1,127 1,061 129 11 2015 1,374 1,342 1,269 1,290 1,218 1,157 202 12 2016 1,392 1,416 1,414 1,394 1,341 286 14 2017 1,466 1,499 1,495 1,474 494 20 2018 1,602 1,650 1,659 780 22 2019 1,670 1,691 1,204 17 2020 1,704 1,529 13 Incurred losses and ALAE $ 13,032 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 16 $ 82 $ 200 $ 356 $ 517 $ 632 $ 711 $ 767 $ 822 $ 842 2012 15 93 218 377 522 642 725 789 830 2013 15 90 219 368 518 635 743 793 2014 21 106 238 396 540 671 752 2015 23 108 218 382 543 663 2016 22 115 274 461 620 2017 27 128 300 457 2018 35 166 367 2019 39 160 2020 34 Paid losses and ALAE 5,518 Net unpaid losses and ALAE for 2011– 2020 accident years 7,514 Net unpaid losses and ALAE for accident years before 2011 383 Net unpaid losses and ALAE $ 7,897 * Unaudited required supplemental information
Berkshire Hathaway Primary Group [Member] | Insurance Group [Member] | Workers' Compensation and Other Casualty [Member]
Schedule of incurred and paid losses and allocated loss adjustment expenses	BH Primary Workers’ Compensation and Other Casualty We periodically evaluate ultimate loss and loss adjustment expense estimates for the workers’ compensation and other casualty claims using a combination of commonly accepted actuarial methodologies such as the Bornhuetter-Ferguson and chain-ladder approaches using paid and incurred loss data. Paid and incurred loss data is segregated and analyzed by state due to the different state regulatory frameworks that may impact certain factors, including the duration and amount of loss payments. We also separately study the various components of liabilities, such as employee lost wages, medical expenses and the costs of claims investigations and administration. We establish case liabilities for reported claims based upon the facts and circumstances of the claim. The excess of the ultimate projected losses, including the expected development of case estimates, and the case-basis liabilities is included in IBNR liabilities. Incurred Losses and ALAE through December 31, Cumulative Number of Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities Reported Claims (in thousands) 2011 $ 738 $ 675 $ 675 $ 624 $ 621 $ 618 $ 607 $ 596 $ 591 $ 576 $ 39 46 2012 873 850 837 791 780 762 750 736 718 53 53 2013 1,258 1,228 1,178 1,127 1,096 1,072 1,050 1,028 120 67 2014 1,743 1,638 1,614 1,548 1,482 1,497 1,477 190 90 2015 2,169 2,127 2,042 2,014 2,025 1,997 267 111 2016 2,511 2,422 2,359 2,325 2,365 470 115 2017 3,044 2,907 2,842 2,843 691 138 2018 3,544 3,412 3,480 1,152 160 2019 4,074 4,102 1,788 170 2020 4,421 2,987 120 Incurred losses and ALAE $ 23,007 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 109 $ 220 $ 333 $ 403 $ 453 $ 481 $ 496 $ 505 $ 512 $ 519 2012 116 299 414 501 560 592 611 626 634 2013 177 422 609 725 793 835 858 874 2014 239 557 800 1,007 1,111 1,176 1,214 2015 289 700 1,017 1,289 1,488 1,570 2016 329 775 1,148 1,461 1,661 2017 441 1,003 1,434 1,771 2018 538 1,198 1,683 2019 682 1,478 2020 695 Paid losses and ALAE 12,099 Net unpaid losses and ALAE for 2011 – 2020 accident years 10,908 Net unpaid losses and ALAE for accident years before 2011 386 Net unpaid losses and ALAE $ 11,294 * Unaudited required supplemental information
Berkshire Hathaway Reinsurance Group [Member] | Insurance Group [Member] | Property [Member]
Schedule of incurred and paid losses and allocated loss adjustment expenses	BHRG’s disaggregated incurred and paid losses and ALAE are summarized by accident year, net of reinsurance. IBNR and case development liabilities are as of December 31, 2020. Dollars are in millions. BHRG Property Incurred Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities 2011 $ 4,111 $ 4,095 $ 3,804 $ 3,711 $ 3,707 $ 3,672 $ 3,654 $ 3,638 $ 3,627 $ 3,616 $ 30 2012 3,153 2,846 2,644 2,403 2,351 2,348 2,329 2,315 2,305 35 2013 3,255 3,093 2,745 2,653 2,631 2,570 2,518 2,504 45 2014 2,648 2,436 2,322 2,178 2,123 2,050 2,021 48 2015 3,287 3,135 2,577 2,979 2,976 3,000 143 2016 3,293 3,923 3,646 3,614 3,616 218 2017 5,291 4,986 4,837 4,727 187 2018 4,426 4,524 4,397 678 2019 4,146 4,299 952 2020 5,858 3,129 Incurred losses and ALAE $ 36,343 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 609 $ 2,259 $ 2,917 $ 3,188 $ 3,304 $ 3,387 $ 3,429 $ 3,474 $ 3,493 $ 3,507 2012 262 1,232 1,813 1,950 2,040 2,117 2,135 2,181 2,199 2013 526 1,459 1,906 2,105 2,226 2,307 2,347 2,376 2014 467 1,249 1,574 1,713 1,779 1,829 1,858 2015 581 1,614 1,969 2,166 2,271 2,453 2016 709 1,811 2,208 2,670 2,923 2017 1,028 2,734 3,660 3,972 2018 915 2,341 2,868 2019 751 2,282 2020 960 Paid losses and ALAE 25,398 Net unpaid losses and ALAE for 2011 – 2020 accident years 10,945 Net unpaid losses and ALAE for accident years before 2011 335 Net unpaid losses and ALAE $ 11,280 * Unaudited required supplemental information
Berkshire Hathaway Reinsurance Group [Member] | Insurance Group [Member] | Casualty [Member]
Schedule of incurred and paid losses and allocated loss adjustment expenses	BHRG Casualty Incurred Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 IBNR and Case Development Liabilities 2011 $ 2,635 $ 2,726 $ 2,595 $ 2,536 $ 2,447 $ 2,354 $ 2,346 $ 2,307 $ 2,272 $ 2,255 $ 279 2012 2,820 3,002 2,837 2,899 2,827 2,712 2,645 2,588 2,581 317 2013 2,160 2,298 2,328 2,170 2,114 2,060 1,964 1,892 387 2014 1,900 2,099 2,068 2,030 1,944 1,980 1,970 537 2015 1,902 2,109 2,137 2,035 1,908 1,870 455 2016 1,928 2,138 2,047 2,003 1,922 555 2017 2,216 2,711 2,588 2,494 762 2018 2,948 3,585 3,509 1,183 2019 3,455 3,931 1,924 2020 3,883 2,754 Incurred losses and ALAE $ 26,307 Cumulative Paid Losses and ALAE through December 31, Accident Year 2011* 2012* 2013* 2014* 2015* 2016* 2017* 2018* 2019* 2020 2011 $ 294 $ 824 $ 1,169 $ 1,412 $ 1,501 $ 1,595 $ 1,673 $ 1,713 $ 1,748 $ 1,776 2012 312 757 1,150 1,381 1,539 1,664 1,764 1,825 1,883 2013 294 530 818 947 1,052 1,155 1,215 1,273 2014 153 488 655 765 889 974 1,119 2015 199 500 725 846 938 1,029 2016 255 563 742 874 972 2017 233 574 830 1,282 2018 267 875 1,649 2019 356 906 2020 406 Paid losses and ALAE 12,295 Net unpaid losses and ALAE for 2011 – 2020 accident years 14,012 Net unpaid losses and ALAE for accident years before 2011 8,878 Net unpaid losses and ALAE $ 22,890 * Unaudited required supplemental information

Retroactive reinsurance contr_2

Retroactive reinsurance contracts (Tables)	12 Months Ended
	Dec. 31, 2020
Insurance [Abstract]
Reconciliation of changes in retroactive reinsurance claim liabilities and deferred charge assets	Reconciliations of the changes in estimated liabilities for retroactive reinsurance unpaid losses and loss adjustment expenses (“claim liabilities”) and related deferred charge reinsurance assumed assets for each of the three years ended December 31, 2020 follow (in millions). 2020 2019 2018 Unpaid losses and loss adjustment expenses Deferred charges reinsurance assumed Unpaid losses and loss adjustment expenses Deferred charges reinsurance assumed Unpaid losses and loss adjustment expenses Deferred charges reinsurance assumed Balances at beginning of year $ 42,441 $ (13,747 ) $ 41,834 $ (14,104 ) $ 42,937 $ (15,278 ) Incurred losses and loss adjustment expenses: Current year contracts — — 1,138 (453 ) 603 (86 ) Prior years’ contracts (399 ) 1,306 378 810 (341 ) 1,260 Total (399 ) 1,306 1,516 357 262 1,174 Paid losses and loss adjustment expenses (1,076 ) — (909 ) — (1,365 ) — Balances at December 31 $ 40,966 $ (12,441 ) $ 42,441 $ (13,747 ) $ 41,834 $ (14,104 ) Incurred losses and loss adjustment expenses, net of deferred charges $ 907 $ 1,873 $ 1,436

Notes payable and other borro_2

Notes payable and other borrowings (Tables)	12 Months Ended
	Dec. 31, 2020
Schedule of short and long term outstanding debt disclosure	Notes payable and other borrowings are summarized below (in millions). The weighted average interest rates and maturity date ranges shown in the following tables are based on borrowings as of December 31, 2020. Weighted Average December 31, Interest Rate 2020 2019 Insurance and other: Berkshire Hathaway Inc. (“Berkshire”): U.S. Dollar denominated due 2021-2047 3.2 % $ 8,308 $ 8,324 Euro denominated due 2021-2035 1.0 % 8,326 7,641 Japanese Yen denominated due 2023-2060 0.7 % 6,031 3,938 Berkshire Hathaway Finance Corporation (“BHFC”): U.S. Dollar denominated due 2021-2050 3.7 % 10,766 8,679 Great Britain Pound denominated due 2039-2059 2.5 % 2,347 2,274 Other subsidiary borrowings due 2021-2045 4.2 % 4,682 5,262 Short-term subsidiary borrowings 2.5 % 1,062 1,472 $ 41,522 $ 37,590
Debt principal payments disclosure	Debt principal repayments expected during each of the next five years are as follows (in millions). Amounts in 2021 include short-term borrowings. 2021 2022 2023 2024 2025 Insurance and other $ 4,354 $ 1,593 $ 6,021 $ 2,343 $ 2,817 Railroad, utilities and energy 5,044 3,405 4,792 3,965 3,777 $ 9,398 $ 4,998 $ 10,813 $ 6,308 $ 6,594
Railroad, Utilities and Energy [Member]
Schedule of short and long term outstanding debt disclosure	Weighted Average December 31, Interest Rate 2020 2019 Railroad, utilities and energy: Berkshire Hathaway Energy Company (“BHE”) and subsidiaries: BHE senior unsecured debt due 2021-2051 4.2 % $ 13,447 $ 8,581 Subsidiary and other debt due 2021-2064 4.1 % 36,420 30,772 Short-term borrowings 1.8 % 2,286 3,214 Burlington Northern Santa Fe ("BNSF") and subsidiaries due 2021-2097 4.6 % 23,220 23,211 $ 75,373 $ 65,778

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of income tax liability	The liabilities for income taxes reflected in our Consolidated Balance Sheets are as follows (in millions). December 31, 2020 2019 Currently payable (receivable) $ (276 ) $ 24 Deferred 73,261 65,823 Other 1,113 952 $ 74,098 $ 66,799
Schedule of deferred tax assets and liabilities	The tax effects of temporary differences that give rise to significant portions of deferred tax assets and deferred tax liabilities are shown below (in millions). December 31, 2020 2019 Deferred tax liabilities: Investments – unrealized appreciation and cost basis differences $ 40,181 $ 32,134 Deferred charges reinsurance assumed 2,613 2,890 Property, plant and equipment and equipment held for lease 30,203 29,388 Goodwill and other intangible assets 6,753 7,293 Other 3,736 3,144 83,486 74,849 Deferred tax assets: Unpaid losses and loss adjustment expenses (1,135 ) (1,086 ) Unearned premiums (900 ) (853 ) Accrued liabilities (2,193 ) (1,981 ) Regulatory liabilities (1,421 ) (1,610 ) Other (4,576 ) (3,496 ) (10,225 ) (9,026 ) Net deferred tax liability $ 73,261 $ 65,823
Schedule of tax provision by jurisdiction category and classification	Income tax expense reflected in our Consolidated Statements of Earnings for each of the three years ending December 31, 2020 is as follows (in millions). 2020 2019 2018 Federal $ 10,596 $ 19,069 $ (1,613 ) State 1,086 625 175 Foreign 758 1,210 1,117 $ 12,440 $ 20,904 $ (321 ) Current $ 5,052 $ 5,818 $ 5,176 Deferred 7,388 15,086 (5,497 ) $ 12,440 $ 20,904 $ (321 )
Schedule of income tax reconciled to federal statutory amount	Income tax expense is reconciled to hypothetical amounts computed at the U.S. federal statutory rate for each of the three years ending December 31, 2020 in the table below (in millions). 2020 2019 2018 Earnings before income taxes $ 55,693 $ 102,696 $ 4,001 Hypothetical income tax expense computed at the U.S. federal statutory rate $ 11,696 $ 21,566 $ 840 Dividends received deduction and tax-exempt interest (448 ) (433 ) (393 ) State income taxes, less U.S. federal income tax benefit 858 494 138 Foreign tax rate differences 13 (6 ) 271 U.S. income tax credits (1,519 ) (942 ) (711 ) Net benefit from the enactment of the TCJA — — (302 ) Goodwill impairments 1,977 20 21 Other differences, net (137 ) 205 (185 ) $ 12,440 $ 20,904 $ (321 ) Effective income tax rate 22.3 % 20.4 % (8.0 )%

Fair value measurements (Tables

Fair value measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Financial assets and liabilities measured at fair value on a recurring basis	Our financial assets and liabilities are summarized below as of December 31, 2020 and December 31, 2019, with fair values shown according to the fair value hierarchy (in millions). The carrying values of cash and cash equivalents, U.S. Treasury Bills, receivables and accounts payable, accruals and other liabilities are considered to be reasonable estimates of their fair values. Carrying Value Fair Value Quoted Prices (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2020 Investments in fixed maturity securities: U.S. Treasury, U.S. government corporations and agencies $ 3,403 $ 3,403 $ 3,358 $ 45 $ — Foreign governments 11,338 11,338 9,259 2,079 — Corporate bonds 5,191 5,191 — 5,191 — Other 478 478 — 478 — Investments in equity securities 281,170 281,170 271,848 38 9,284 Investment in Kraft Heinz common stock 13,336 11,280 11,280 — — Loans and finance receivables 19,201 20,554 — 2,692 17,862 Derivative contract assets (1) 270 270 1 72 197 Derivative contract liabilities: Railroad, utilities and energy (1) 121 121 6 96 19 Equity index put options 1,065 1,065 — — 1,065 Notes payable and other borrowings: Insurance and other 41,522 46,676 — 46,665 11 Railroad, utilities and energy 75,373 92,593 — 92,593 — December 31, 2019 Investments in fixed maturity securities: U.S. Treasury, U.S. government corporations and agencies $ 3,090 $ 3,090 $ 3,046 $ 44 $ — Foreign governments 8,638 8,638 5,437 3,201 — Corporate bonds 6,352 6,352 — 6,350 2 Other 605 605 — 605 — Investments in equity securities 248,027 248,027 237,271 46 10,710 Investment in Kraft Heinz common stock 13,757 10,456 10,456 — — Loans and finance receivables 17,527 17,861 — 1,809 16,052 Derivative contract assets (1) 145 145 — 23 122 Derivative contract liabilities: Railroad, utilities and energy (1) 76 76 6 59 11 Equity index put options 968 968 — — 968 Notes payable and other borrowings: Insurance and other 37,590 40,589 — 40,569 20 Railroad, utilities and energy 65,778 76,237 — 76,237 — (1)
Reconciliations of significant assets and liabilities measured and carried at fair value on a recurring basis with the use of significant unobservable inputs (Level 3)	Reconciliations of assets and liabilities measured and carried at fair value on a recurring basis with the use of significant unobservable inputs (Level 3) for each of the three years ending December 31, 2020 follow (in millions). Investments in equity and fixed maturity securities Net derivative contract liabilities Balance December 31, 2017 $ 6 $ (2,069 ) Gains (losses) included in: Earnings — (118 ) Other comprehensive income — 2 Regulatory assets and liabilities — 3 Acquisitions 2 3 Dispositions and settlements (1 ) (164 ) Balance December 31, 2018 7 (2,343 ) Gains (losses) included in: Earnings 404 1,972 Other comprehensive income — (1 ) Regulatory assets and liabilities — (26 ) Acquisitions 10,000 6 Dispositions and settlements (4 ) (465 ) Balance December 31, 2019 10,407 (857 ) Gains (losses) included in: Earnings (1,426 ) 603 Other comprehensive income — — Regulatory assets and liabilities — (17 ) Acquisitions — 5 Dispositions and settlements (2 ) (621 ) Balance December 31, 2020 $ 8,979 $ (887 )
Fair value assets and liabilities measured on recurring basis, unobservable inputs, additional information	Quantitative information as of December 31, 2020, with respect to assets and liabilities measured and carried at fair value on a recurring basis with the use of significant unobservable inputs (Level 3) follows (in millions). Fair Value Principal Valuation Techniques Unobservable Inputs Weighted Average Investments in equity securities: Preferred stock $ 8,891 Discounted cash flow Expected duration 9 years Discount for transferability restrictions and subordination 375 bps Common stock warrants 86 Warrant pricing model Expected duration 9 years Volatility 32% Derivative contract liabilities 1,065 Option pricing model Volatility 19%

Accumulated other comprehensi_2

Accumulated other comprehensive income (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of accumulated other comprehensive income	A summary of the net changes in after-tax accumulated other comprehensive income attributable to Berkshire Hathaway shareholders for each of the three years ending December 31, 2020 follows (in millions). Unrealized appreciation of investments, net Foreign currency translation Defined benefit pension plans Other Accumulated other comprehensive income Balance December 31, 2017 $ 62,093 $ (3,114 ) $ (420 ) $ 12 $ 58,571 Reclassifications to retained earnings upon adoption of new accounting standards (61,340 ) (65 ) 36 (6 ) (61,375 ) Other comprehensive income, net (383 ) (1,424 ) (432 ) 28 (2,211 ) Balance December 31, 2018 370 (4,603 ) (816 ) 34 (5,015 ) Other comprehensive income, net 111 257 (553 ) (43 ) (228 ) Balance December 31, 2019 481 (4,346 ) (1,369 ) (9 ) (5,243 ) Other comprehensive income, net 55 1,264 (276 ) (43 ) 1,000 Balance December 31, 2020 $ 536 $ (3,082 ) $ (1,645 ) $ (52 ) $ (4,243 )

Common stock (Tables)

Common stock (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Changes in issued, treasury and outstanding Berkshire common stock	Changes in Berkshire’s issued, treasury and outstanding common stock during the three years ending December 31, 2020 are shown in the table below. In addition to our common stock, 1,000,000 shares of preferred stock are authorized, but none are issued. Class A, $5 Par Value (1,650,000 shares authorized) Class B, $0.0033 Par Value (3,225,000,000 shares authorized) Issued Treasury Outstanding Issued Treasury Outstanding Balance December 31, 2017 762,755 (11,680 ) 751,075 1,342,066,749 (1,409,762 ) 1,340,656,987 Conversions of Class A common stock to Class B common stock and exercises of replacement stock options (20,542 ) — (20,542 ) 31,492,234 — 31,492,234 Treasury stock acquired — (1,217 ) (1,217 ) — (4,729,147 ) (4,729,147 ) Balance December 31, 2018 742,213 (12,897 ) 729,316 1,373,558,983 (6,138,909 ) 1,367,420,074 Conversions of Class A common stock to Class B common stock and exercises of replacement stock options (22,906 ) — (22,906 ) 34,624,869 — 34,624,869 Treasury stock acquired — (4,440 ) (4,440 ) — (17,563,410 ) (17,563,410 ) Balance December 31, 2019 719,307 (17,337 ) 701,970 1,408,183,852 (23,702,319 ) 1,384,481,533 Conversions of Class A common stock to Class B common stock and exercises of replacement stock options (40,784 ) — (40,784 ) 61,176,000 — 61,176,000 Treasury stock acquired — (17,255 ) (17,255 ) — (95,614,062 ) (95,614,062 ) Balance December 31, 2020 678,523 (34,592 ) 643,931 1,469,359,852 (119,316,381 ) 1,350,043,471

Revenues from contracts with _2

Revenues from contracts with customers (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue From Contract With Customer [Abstract]
Revenue from contracts with customers disaggregated by reportable segment and source of revenue	The following tables summarize customer contract revenues disaggregated by reportable segment and the source of the revenue for each of the three years ended December 31, 2020 (in millions). Other revenues included in consolidated revenues were primarily insurance premiums earned, interest, dividend and other investment income and leasing revenues, which are not considered to be revenues from contracts with customers under GAAP. 2020 Manufacturing McLane Company Service and retailing BNSF Berkshire Hathaway Energy Insurance, Corporate and other Total Manufactured products: Industrial and commercial products $ 20,772 $ — $ 192 $ — $ — $ — $ 20,964 Building products 15,943 — — — — — 15,943 Consumer products 14,757 — — — — — 14,757 Grocery and convenience store distribution — 30,795 — — — — 30,795 Food and beverage distribution — 15,368 — — — — 15,368 Auto sales — — 8,258 — — — 8,258 Other retail and wholesale distribution 2,452 — 12,470 — — — 14,922 Service 1,456 584 3,332 20,693 4,595 — 30,660 Electricity and natural gas — — — — 15,066 — 15,066 Total 55,380 46,747 24,252 20,693 19,661 — 166,733 Other revenues 3,598 93 3,859 57 1,353 69,817 78,777 $ 58,978 $ 46,840 $ 28,111 $ 20,750 $ 21,014 $ 69,817 $ 245,510 2019 Manufactured products: Industrial and commercial products $ 25,311 $ — $ 184 $ — $ — $ — $ 25,495 Building products 15,620 — — — — — 15,620 Consumer products 14,120 — — — — — 14,120 Grocery and convenience store distribution — 33,057 — — — — 33,057 Food and beverage distribution — 16,767 — — — — 16,767 Auto sales — — 8,481 — — — 8,481 Other retail and wholesale distribution 2,299 — 12,213 — — — 14,512 Service 1,642 539 4,062 23,302 4,096 — 33,641 Electricity and natural gas — — — — 14,819 — 14,819 Total 58,992 50,363 24,940 23,302 18,915 — 176,512 Other revenues 3,632 95 4,459 55 1,181 68,682 78,104 $ 62,624 $ 50,458 $ 29,399 $ 23,357 $ 20,096 $ 68,682 $ 254,616 2018 Manufactured products: Industrial and commercial products $ 25,707 $ — $ 204 $ — $ — $ — $ 25,911 Building products 14,323 — — — — — 14,323 Consumer products 14,790 — — — — — 14,790 Grocery and convenience store distribution — 33,518 — — — — 33,518 Food and beverage distribution — 16,309 — — — — 16,309 Auto sales — — 8,181 — — — 8,181 Other retail and wholesale distribution 2,091 — 12,067 — — — 14,158 Service 1,519 84 4,100 23,652 3,949 — 33,304 Electricity and natural gas — — — — 14,951 — 14,951 Total 58,430 49,911 24,552 23,652 18,900 — 175,445 Other revenues 3,340 76 4,297 51 1,070 63,558 72,392 $ 61,770 $ 49,987 $ 28,849 $ 23,703 $ 19,970 $ 63,558 $ 247,837
Transaction price allocated to significant unsatisfied remaining performance obligations and timing of when performance obligations expected to be satisfied	A summary of the transaction price allocated to the significant unsatisfied remaining performance obligations relating to contracts with expected durations in excess of one year as of December 31, 2020 and the timing of when the performance obligations are expected to be satisfied follows (in millions). Less than 12 months Greater than 12 months Total Electricity and natural gas $ 3,210 $ 22,088 $ 25,298 Other sales and service contracts 1,228 2,382 3,610

Pension plans (Tables)

Pension plans (Tables)	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Schedule of net periodic pension expense	The components of our net periodic pension expense for each of the three years ending December 31, 2020 follow (in millions). 2020 2019 2018 Service cost $ 235 $ 224 $ 271 Interest cost 510 618 593 Expected return on plan assets (955 ) (936 ) (988 ) Amortization of actuarial losses and other 171 26 188 Net periodic pension expense $ (39 ) $ (68 ) $ 64
Schedule of changes in projected benefit obligations, changes in plan assets and net funded status	The funded status at year end 2020 and 2019 and reconciliations of the changes in PBOs and plan assets related to BHE’s pension plans and all other pension plans for each of the two years ending December 31, 2020 follow (in millions). 2020 2019 BHE Other Total BHE Other Total Benefit obligations PBO beginning of year $ 4,898 $ 13,808 $ 18,706 $ 4,551 $ 12,371 $ 16,922 Service cost 33 202 235 32 192 224 Interest cost 133 377 510 161 457 618 Benefits paid (285 ) (709 ) (994 ) (257 ) (776 ) (1,033 ) Settlements (63 ) (12 ) (75 ) (121 ) (46 ) (167 ) Actuarial (gains) or losses and other 566 1,481 2,047 532 1,610 2,142 PBO end of year $ 5,282 $ 15,147 $ 20,429 $ 4,898 $ 13,808 $ 18,706 Plan assets Plan assets beginning of year $ 4,808 $ 11,688 $ 16,496 $ 4,385 $ 10,574 $ 14,959 Employer contributions 69 127 196 68 131 199 Benefits paid (285 ) (709 ) (994 ) (257 ) (776 ) (1,033 ) Actual return on plan assets 554 1,820 2,374 650 1,764 2,414 Settlements (63 ) (12 ) (75 ) (121 ) (46 ) (167 ) Other 75 (134 ) (59 ) 83 41 124 Plan assets end of year $ 5,158 $ 12,780 $ 17,938 $ 4,808 $ 11,688 $ 16,496 Funded status – net liability $ 124 $ 2,367 $ 2,491 $ 90 $ 2,120 $ 2,210
Schedule of information for plans with PBOs in excess of plan assets	Information for plans with PBOs and ABOs in excess of plan assets as of December 31, 2020 and 2019 follows (in millions) 2020 2019 PBOs $ 12,775 $ 12,625 Plan assets 9,018 9,627 ABOs 10,875 10,617 Plan assets 7,820 8,367
Schedule of information for plans with ABOs in excess of plan assets	Information for plans with PBOs and ABOs in excess of plan assets as of December 31, 2020 and 2019 follows (in millions) 2020 2019 PBOs $ 12,775 $ 12,625 Plan assets 9,018 9,627 ABOs 10,875 10,617 Plan assets 7,820 8,367
Schedule of weighted average assumptions	Weighted average assumptions used in determining PBOs and net periodic pension expense follow. 2020 2019 2018 Discount rate applicable to pension benefit obligations 2.3 % 3.1 % 3.9 % Expected long-term rate of return on plan assets 6.2 6.4 6.4 Rate of compensation increase 2.6 2.5 2.6 Discount rate applicable to net periodic pension expense 3.1 4.0 3.4
Schedule of fair value measurements by major categories of plan assets	Fair value measurements of plan assets as of December 31, 2020 and 2019 follow (in millions). Fair Value Investment funds and partnerships Total Level 1 Level 2 Level 3 at net asset value December 31, 2020 Cash and cash equivalents $ 383 $ 243 $ 140 $ — $ — Equity securities 11,383 10,123 851 409 — Fixed maturity securities 3,173 2,214 926 33 — Investment funds and other 2,999 198 398 56 2,347 $ 17,938 $ 12,778 $ 2,315 $ 498 $ 2,347 December 31, 2019 Cash and cash equivalents $ 412 $ 309 $ 103 $ — $ — Equity securities 11,105 9,860 836 409 — Fixed maturity securities 2,328 1,593 704 31 — Investment funds and other 2,651 143 358 40 2,110 $ 16,496 $ 11,905 $ 2,001 $ 480 $ 2,110
Schedule of pension plan amounts recognized In accumulated other comprehensive income	A reconciliation of the pre-tax accumulated other comprehensive income (loss) related to defined benefit pension plans for each of the two years ending December 31, 2020 follows (in millions). 2020 2019 Balance beginning of year $ (1,896 ) $ (1,184 ) Amount included in net periodic pension expense 141 94 Actuarial gains (losses) and other (496 ) (806 ) Balance end of year $ (2,251 ) $ (1,896 )

Supplemental cash flow inform_2

Supplemental cash flow information (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Schedule of supplemental cash flow information	A summary of supplemental cash flow information for each of the three years ending December 31, 2020 is presented in the following table (in millions). 2020 2019 2018 Cash paid during the period for: Income taxes $ 5,001 $ 5,415 $ 4,354 Interest: Insurance and other 1,001 1,011 1,111 Railroad, utilities and energy 3,006 2,879 2,867 Non-cash investing and financing activities: Liabilities assumed in connection with business acquisitions 6,981 766 3,735 Operating lease liabilities arising from obtaining right-of-use assets 729 782 —

Business segment data (Tables)

Business segment data (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of revenues, earnings before income taxes, interest expense, income tax expense, capital expenditures, depreciation, goodwill and identifiable assets by segment	A disaggregation of our consolidated data for each of the three most recent years is presented as follows (in millions). Revenues Earnings before income taxes 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance: Underwriting: GEICO $ 35,093 $ 35,572 $ 33,363 $ 3,428 $ 1,506 $ 2,449 Berkshire Hathaway Primary Group 9,615 9,165 8,111 110 383 670 Berkshire Hathaway Reinsurance Group 18,693 16,341 15,944 (2,700 ) (1,472 ) (1,109 ) Insurance underwriting 63,401 61,078 57,418 838 417 2,010 Investment income 5,960 6,615 5,518 5,949 6,600 5,503 Total insurance 69,361 67,693 62,936 6,787 7,017 7,513 BNSF 20,869 23,515 23,855 6,792 7,250 6,863 Berkshire Hathaway Energy 21,031 20,114 19,987 2,479 2,618 2,472 Manufacturing 59,079 62,730 61,883 8,010 9,522 9,366 McLane Company 46,840 50,458 49,987 251 288 246 Service and retailing 28,178 29,487 28,939 2,628 2,555 2,696 245,358 253,997 247,587 26,947 29,250 29,156 Reconciliation to consolidated amount Investment and derivative gains/losses — — — 40,746 72,607 (22,455 ) Interest expense, not allocated to segments — — — (483 ) (416 ) (458 ) Equity method investments — — — 726 1,176 (2,167 ) Goodwill and intangible asset impairments — — — (10,671 ) (96 ) (382 ) Corporate, eliminations and other 152 619 250 (1,572 ) 175 307 $ 245,510 $ 254,616 $ 247,837 $ 55,693 $ 102,696 $ 4,001 Interest expense Income tax expense 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance $ — $ — $ — $ 1,089 $ 1,166 $ 1,374 BNSF 1,037 1,070 1,041 1,631 1,769 1,644 Berkshire Hathaway Energy 1,941 1,835 1,777 (1,010 ) (526 ) (452 ) Manufacturing 737 752 690 1,795 2,253 2,188 McLane Company — — 15 71 71 59 Service and retailing 61 86 91 669 603 634 3,776 3,743 3,614 4,245 5,336 5,447 Reconciliation to consolidated amount Investment and derivative gains/losses — — — 8,855 15,159 (4,673 ) Interest expense, not allocated to segments 483 416 458 (102 ) (88 ) (96 ) Equity method investments — — — 57 148 (753 ) Corporate, eliminations and other (176 ) (198 ) (219 ) (615 ) 349 (246 ) $ 4,083 $ 3,961 $ 3,853 $ 12,440 $ 20,904 $ (321 ) Notes to Consolidated Financial Statements (Continued) (27) Business segment data (Continued) Capital expenditures Depreciation of tangible assets 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance $ 50 $ 108 $ 130 $ 74 $ 82 $ 79 BNSF 3,063 3,608 3,187 2,423 2,350 2,268 Berkshire Hathaway Energy 6,765 7,364 6,241 3,376 2,947 2,830 Manufacturing 2,133 2,981 3,116 2,026 1,951 1,890 McLane Company 98 158 276 204 225 204 Service and retailing 903 1,760 1,587 1,216 1,192 1,115 $ 13,012 $ 15,979 $ 14,537 $ 9,319 $ 8,747 $ 8,386 Goodwill at year-end Identifiable assets at year-end 2020 2019 2018 2020 2019 2018 Operating Businesses Insurance $ 15,224 $ 15,289 $ 15,289 $ 399,169 $ 364,550 $ 289,746 BNSF 14,851 14,851 14,851 73,809 73,699 70,242 Berkshire Hathaway Energy 11,763 9,979 9,851 109,286 88,651 80,543 Manufacturing 25,512 34,800 34,019 104,318 104,437 99,912 McLane Company 232 734 734 6,771 6,872 6,243 Service and retailing 6,152 6,229 6,281 26,173 26,494 24,724 $ 73,734 $ 81,882 $ 81,025 719,526 664,703 571,410 Reconciliation to consolidated amount Corporate and other 80,469 71,144 55,359 Goodwill 73,734 81,882 81,025 $ 873,729 $ 817,729 $ 707,794
Schedule of premiums written and earned	Property/casualty and life/health insurance premiums written and earned are summarized below (in millions). Property/Casualty Life/Health 2020 2019 2018 2020 2019 2018 Premiums Written: Direct $ 47,838 $ 47,578 $ 44,513 $ 510 $ 839 $ 1,111 Assumed 11,533 10,214 8,970 5,960 5,046 5,540 Ceded (898 ) (821 ) (869 ) (42 ) (45 ) (49 ) $ 58,473 $ 56,971 $ 52,614 $ 6,428 $ 5,840 $ 6,602 Premiums Earned: Direct $ 46,418 $ 46,540 $ 43,095 $ 510 $ 839 $ 1,111 Assumed 11,449 9,643 8,649 5,973 4,952 5,438 Ceded (907 ) (851 ) (825 ) (42 ) (45 ) (50 ) $ 56,960 $ 55,332 $ 50,919 $ 6,441 $ 5,746 $ 6,499
Schedule of insurance premiums written by geographic region	Insurance premiums written by geographic region (based upon the domicile of the insured or reinsured) are summarized below (in millions). Property/Casualty Life/Health 2020 2019 2018 2020 2019 2018 United States $ 50,250 $ 50,529 $ 46,146 $ 2,820 $ 2,553 $ 3,598 Western Europe 3,751 2,535 2,157 1,120 908 939 Asia Pacific 3,410 3,114 3,726 1,652 1,582 1,361 All other 1,062 793 585 836 797 704 $ 58,473 $ 56,971 $ 52,614 $ 6,428 $ 5,840 $ 6,602

Quarterly data (Tables)

Quarterly data (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly revenues and earnings	A summary of revenues and net earnings by quarter for each of the last two years follows. This information is unaudited. Amounts are in millions, except per share amounts. 1 st Quarter 2 nd Quarter 3 rd Quarter 4 th Quarter 2020 Revenues $ 61,265 $ 56,840 $ 63,024 $ 64,381 Net earnings (loss) attributable to Berkshire shareholders * (49,746 ) 26,295 30,137 35,835 Net earnings (loss) attributable to Berkshire shareholders per equivalent Class A common share (30,653 ) 16,314 18,994 23,015 2019 Revenues $ 60,678 $ 63,598 $ 64,972 $ 65,368 Net earnings attributable to Berkshire shareholders * 21,661 14,073 16,524 29,159 Net earnings attributable to Berkshire shareholders per equivalent Class A common share 13,209 8,608 10,119 17,909 * Includes after-tax investment and derivative gains/losses as follows: 1 st Quarter 2 nd Quarter 3 rd Quarter 4 th Quarter 2020 $ (55,617 ) $ 31,645 $ 24,737 $ 30,826 2019 16,106 7,934 8,666 24,739

Significant accounting polici_4

Significant accounting policies and practices - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Voting interests of investee	20.00%
Percentage of LIFO Inventory	35.00%
Excess of current or replacement costs over costs determined under LIFO	$ 1,100		$ 950
Retained earnings	444,626		402,493
Operating leases, right of use assets	5,579		5,941
Operating lease liabilities	5,469		5,882
Assets	873,729		817,729		$ 707,794
Liabilities	$ 422,393		389,166
Difference Between Lease Guidance in Effect Before and After Topic 842 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating leases, right of use assets				$ 6,200
Operating lease liabilities				5,900
ASU 2016-13 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
ASU 2016-13 [Member] | Cumulative effect, period of adoption, adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ (388)
ASC 842 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2019
ASC 842 [Member] | Difference Between Lease Guidance in Effect Before and After Topic 842 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets				(300)
Assets				5,900
Liabilities				$ 5,900
ASU 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings						$ 61,459
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2018
Other Assets [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Unamortized balances of deferred policy acquisition costs	$ 3,250		$ 2,950
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Trade receivables, insurance premium receivables and other receivables collection term	1 year
Insurance interest rate assumption	7.00%
Maximum [Member] | Buildings and improvements [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	50 years
Maximum [Member] | Machinery and equipment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	25 years
Maximum [Member] | Furniture, fixtures and other [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	15 years
Maximum [Member] | Track structure and other roadway [Member] | Railroad [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	100 years
Maximum [Member] | Locomotives, freight cars and other equipment [Member] | Railroad [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	43 years
Maximum [Member] | Utility generation, transmission and distribution systems [Member] | Utilities and Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	80 years
Maximum [Member] | Interstate natural gas pipeline assets [Member] | Utilities and Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	80 years
Maximum [Member] | Independent power plants and other assets [Member] | Utilities and Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	40 years
Maximum [Member] | Equipment held for lease [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	35 years
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Insurance interest rate assumption	3.00%
Minimum [Member] | Buildings and improvements [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	5 years
Minimum [Member] | Machinery and equipment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	3 years
Minimum [Member] | Furniture, fixtures and other [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	3 years
Minimum [Member] | Track structure and other roadway [Member] | Railroad [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	10 years
Minimum [Member] | Locomotives, freight cars and other equipment [Member] | Railroad [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	6 years
Minimum [Member] | Utility generation, transmission and distribution systems [Member] | Utilities and Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	5 years
Minimum [Member] | Interstate natural gas pipeline assets [Member] | Utilities and Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	3 years
Minimum [Member] | Independent power plants and other assets [Member] | Utilities and Energy [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	3 years
Minimum [Member] | Equipment held for lease [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful life (in years)	3 years

Summary of effects of initial a

Summary of effects of initial adoption of ASU 2016-01, ASU 2018-02 and ASC 606 (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive income	$ (4,243)	$ (5,243)
Retained earnings	444,626	402,493
Total shareholders’ equity	$ 451,336	$ 428,563	$ 352,500		$ 351,954
ASU 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive income				$ (61,459)
Retained earnings				61,459
ASU 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive income				84
Retained earnings				(84)
ASC 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings				(70)
Total shareholders’ equity				(70)
Adjustments for New Accounting Pronouncements [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated other comprehensive income				(61,375)
Retained earnings				61,305
Total shareholders’ equity				$ (70)

Business acquisitions - Narrati

Business acquisitions - Narrative (Detail) $ in Millions	Nov. 01, 2020USD ($)Bcfemi	Oct. 05, 2020	Oct. 01, 2018USD ($)	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Aggregate consideration paid for acquisitions, net of cash acquired					$ 2,532	$ 1,683	$ 3,279
MLMIC Insurance Company [Member]
Business Acquisition [Line Items]
Acquisition price			$ 2,500
Assets			6,100
Investments			5,200
Liabilities			3,600
Unpaid losses and loss adjustment expenses			$ 3,200
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Aggregate consideration paid for acquisitions, net of cash acquired					$ 130	$ 1,700	$ 1,000
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member]
Business Acquisition [Line Items]
Business acquisition, contingent acquisition description					to acquire substantially all of Dominion’s natural gas transmission and storage business.
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | Cove Point [Member]
Business Acquisition [Line Items]
Variable interest entity, ownership percentage	25.00%
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | Cove Point [Member] | General Partner [Member]
Business Acquisition [Line Items]
Variable interest entity, ownership percentage	100.00%
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | Cove Point [Member] | Limited Partner [Member]
Business Acquisition [Line Items]
Variable interest entity, ownership percentage	25.00%
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | First Acquisition Agreement [Member]
Business Acquisition [Line Items]
Business acquisition, date of acquisition		Oct. 5, 2020
Business acquisition, date of completed	Nov. 1, 2020
Payment for acquisition of business in cash after post-closing adjustments	$ 2,500
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | First Acquisition Agreement [Member] | Cove Point [Member]
Business Acquisition [Line Items]
Natural gas storage capacity acquired | Bcfe	420
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | First Acquisition Agreement [Member] | Cove Point [Member] | Minimum [Member]
Business Acquisition [Line Items]
Business acquisition, length of pipelines acquired | mi	5,400
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | Second Acquisition Agreement [Member]
Business Acquisition [Line Items]
Business acquisition, date of acquisition		Oct. 5, 2020
Berkshire Hathaway Energy [Member] | Dominion Energy, Inc. [Member] | Second Acquisition Agreement [Member] | Forecast [Member]
Business Acquisition [Line Items]
Payment for acquisition of business in cash				$ 1,300

Business Acquisitions - Summary

Business Acquisitions - Summary of preliminary fair values of identified assets acquired and liabilities assumed and residual goodwill (Detail) - USD ($) $ in Millions	Dec. 31, 2020	[1]	Nov. 01, 2020	Dec. 31, 2019	[1]	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 73,734			$ 81,882		$ 81,025
Dominion
Business Acquisition [Line Items]
Property, plant and equipment			$ 9,254
Goodwill			1,732
Other			2,376
Assets acquired			13,362
Notes payable and other borrowings			5,615
Other			1,317
Liabilities assumed			6,932
Noncontrolling interests			3,916
Net assets			$ 2,514
[1]	Net of accumulated goodwill impairments of $11.0 billion as of December 31, 2020 and $1.1 billion as of December 31, 2019.

Investments in fixed maturity_3

Investments in fixed maturity securities (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Summary of Investment Holdings [Line Items]
Amortized cost of fixed maturity securities	$ 19,724	$ 18,073
Unrealized gains on fixed maturity securities	695	626
Unrealized losses on fixed maturity securities	(9)	(14)
Fair value of fixed maturity securities	20,410	18,685
U.S. Treasury, U.S. government corporations and agencies [Member]
Summary of Investment Holdings [Line Items]
Amortized cost of fixed maturity securities	3,348	3,054
Unrealized gains on fixed maturity securities	55	37
Unrealized losses on fixed maturity securities		(1)
Fair value of fixed maturity securities	3,403	3,090
Foreign governments [Member]
Summary of Investment Holdings [Line Items]
Amortized cost of fixed maturity securities	11,233	8,584
Unrealized gains on fixed maturity securities	110	63
Unrealized losses on fixed maturity securities	(5)	(9)
Fair value of fixed maturity securities	11,338	8,638
Corporate bonds [Member]
Summary of Investment Holdings [Line Items]
Amortized cost of fixed maturity securities	4,729	5,896
Unrealized gains on fixed maturity securities	464	459
Unrealized losses on fixed maturity securities	(2)	(3)
Fair value of fixed maturity securities	5,191	6,352
Other [Member]
Summary of Investment Holdings [Line Items]
Amortized cost of fixed maturity securities	414	539
Unrealized gains on fixed maturity securities	66	67
Unrealized losses on fixed maturity securities	(2)	(1)
Fair value of fixed maturity securities	$ 478	$ 605

Investments in fixed maturity_4

Investments in fixed maturity securities - Narrative (Detail)	Dec. 31, 2020
Foreign governments [Member] | AA or Higher Credit Rating [Member]
Summary of Investment Holdings [Line Items]
Percentage of fixed maturity investments by credit rating	88.00%

Investments in fixed maturity_5

Investments in fixed maturity securities - Amortized cost and estimated fair value of securities with fixed maturities (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Summary of Investment Holdings [Line Items]
Due in one year or less - amortized cost	$ 10,379
Due after one year through five years - amortized cost	8,323
Due after five years through ten years - amortized cost	373
Due after ten years - amortized cost	337
Amortized cost of fixed maturity securities	19,724	$ 18,073
Due in one year or less - fair value	10,448
Due after one year through five years - fair value	8,456
Due after five years through ten years - fair value	496
Due after ten years - fair value	640
Fair value of fixed maturity securities	20,410	$ 18,685
Mortgage-backed securities [Member]
Summary of Investment Holdings [Line Items]
Amortized cost of mortgage-backed securities	312
Fair value of mortgage-backed securities	$ 370

Investments in equity securit_3

Investments in equity securities (Detail) - USD ($) $ in Millions	Dec. 31, 2020		Dec. 31, 2019
Summary of Investment Holdings [Line Items]
Cost Basis	$ 108,620		$ 110,340
Net Unrealized Gains	172,550		137,687
Fair Value	281,170	[1]	248,027	[2]
Banks, insurance and finance [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	26,312		40,419
Net Unrealized Gains	40,167		61,976
Fair Value	66,479		102,395
Consumer products [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	34,747		38,887
Net Unrealized Gains	111,583		60,747
Fair Value	146,330		99,634
Commercial, industrial and other [Member]
Summary of Investment Holdings [Line Items]
Cost Basis	47,561		31,034
Net Unrealized Gains	20,800		14,964
Fair Value	$ 68,361		$ 45,998
[1]	Approximately 68% of the aggregate fair value was concentrated in four companies (American Express Company – $18.3 billion; Apple Inc. – $120.4 billion; Bank of America Corporation – $31.3 billion and The Coca-Cola Company – $21.9 billion).
[2]	Approximately 60% of the aggregate fair value was concentrated in four companies (American Express Company – $18.9 billion; Apple Inc. – $73.7 billion; Bank of America Corporation – $33.4 billion and The Coca-Cola Company – $22.1 billion).

Investments in equity securit_4

Investments in equity securities (Parenthetical) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)Company		Dec. 31, 2019USD ($)Company
Summary of Investment Holdings [Line Items]
Fair value of investments	$ 281,170	[1]	$ 248,027	[2]
American Express Company [Member]
Summary of Investment Holdings [Line Items]
Fair value of investments	18,300		18,900
Apple Inc. [Member]
Summary of Investment Holdings [Line Items]
Fair value of investments	120,400		73,700
Bank of America Corporation [Member]
Summary of Investment Holdings [Line Items]
Fair value of investments	31,300		33,400
The Coca-Cola Company [Member]
Summary of Investment Holdings [Line Items]
Fair value of investments	$ 21,900		$ 22,100
Equity Securities [Member] | Investment Concentration [Member]
Summary of Investment Holdings [Line Items]
Concentration percentage	68.00%		60.00%
Number of companies in concentration percentage | Company	4		4
[1]	Approximately 68% of the aggregate fair value was concentrated in four companies (American Express Company – $18.3 billion; Apple Inc. – $120.4 billion; Bank of America Corporation – $31.3 billion and The Coca-Cola Company – $21.9 billion).
[2]	Approximately 60% of the aggregate fair value was concentrated in four companies (American Express Company – $18.9 billion; Apple Inc. – $73.7 billion; Bank of America Corporation – $33.4 billion and The Coca-Cola Company – $22.1 billion).

Investments in equity securit_5

Investments in equity securities - Narrative (Detail) - Investment Commitment [Member] - USD ($) $ / shares in Units, $ in Billions	Aug. 03, 2020	Aug. 08, 2019	Dec. 31, 2020
Summary of Investment Holdings [Line Items]
Investment commitment description			On August 8, 2019, Berkshire invested a total of $10 billion in Occidental Corporation (“Occidental”) newly issued Occidental Cumulative Perpetual Preferred Stock with an aggregate liquidation value of $10 billion and warrants to purchase up to 80 million shares of Occidental common stock at an exercise price of $62.50 per share. In accordance with the terms of the warrants, on August 3, 2020, the number of shares of common stock that can be purchased was increased to 83.86 million shares and the exercise price was reduced to $59.62 per share. The preferred stock accrues dividends at 8% per annum and is redeemable at the option of Occidental commencing in 2029 at a redemption price equal to 105% of the liquidation preference plus any accumulated and unpaid dividends, or is mandatorily redeemable under certain specified capital return events. Dividends on the preferred stock may be paid in cash or, at Occidental’s option, in shares of Occidental common stock. The warrants are exercisable in whole or in part until one year after the redemption of the preferred stock. Our investments in Occidental are included in the commercial, industrial and other category in the preceding tables.
Occidental Corporation [Member] | Cumulative Perpetual Preferred Stock [Member]
Summary of Investment Holdings [Line Items]
Investment in preferred stock, liquidation value		$ 10
Investment in preferred stock, stated dividend rate		8.00%
Investment in preferred stock, redemption year start		2029
Investment in preferred stock, redemption price percentage of liquidation preference		105.00%
Occidental Corporation [Member] | Cumulative Perpetual Preferred Stock and Warrants [Member]
Summary of Investment Holdings [Line Items]
Investment commitment amount		$ 10
Occidental Corporation [Member] | Warrant [Member]
Summary of Investment Holdings [Line Items]
Number of common shares that can be purchased	83,860,000	80,000,000
Exercise price for warrants, per share		$ 62.50
Exercise price for warrants, per share	$ 59.62

Equity method investments - Nar

Equity method investments - Narrative (Detail)	Oct. 03, 2017	Dec. 31, 2020USD ($)StoreLocationsharesgal	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		20.00%
Equity method earnings (losses)		$ 726,000,000	$ 1,176,000,000	$ (2,167,000,000)
Berkshire Hathaway Inc. (Parent) [Member]
Schedule of Equity Method Investments [Line Items]
Equity method earnings (losses)		95,000,000	493,000,000	(2,730,000,000)
Equity method investments, carrying value		$ 13,336,000,000	13,757,000,000
Pilot Travel Centers LLC [Member]
Schedule of Equity Method Investments [Line Items]
Number of retail | Store		950
Pilot Travel Centers LLC [Member] | U.S. States [Member]
Schedule of Equity Method Investments [Line Items]
Number of fueling locations | Location		44
Pilot Travel Centers LLC [Member] | Canadian Provinces [Member]
Schedule of Equity Method Investments [Line Items]
Number of fueling locations | Location		6
Pilot Travel Centers LLC [Member] | Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Gallons of fuel purchased annually | gal		11,000,000,000
Pilot Travel Centers LLC [Member] | Berkshire Hathaway Inc. (Parent) [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	38.60%
Pilot Travel Centers LLC [Member] | Berkshire Hathaway Inc. (Parent) [Member] | Agreement to Acquire Additional Interest in 2023 [Member]
Schedule of Equity Method Investments [Line Items]
Percentage of additional interest to be acquired		41.40%
Haslam Family [Member] | Pilot Travel Centers LLC [Member]
Schedule of Equity Method Investments [Line Items]
Majority ownership percentage		50.10%
Haslam Family [Member] | Pilot Travel Centers LLC [Member] | Agreement to Acquire Additional Interest in 2023 [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage		20.00%
Third Party [Member] | Pilot Travel Centers LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage		11.30%
The Kraft Heinz Company [Member]
Schedule of Equity Method Investments [Line Items]
Number of shares owned | shares		325,442,152
Equity method investment ownership percentage		26.60%
Equity method earnings (losses)		$ 95,000,000	493,000,000	(2,700,000,000)
Equity method investee, impairment charges		850,000,000	450,000,000	3,700,000,000
Common stock dividends received		521,000,000	521,000,000	814,000,000
Equity method investments, fair value		11,300,000,000	10,500,000,000
Equity method investments, carrying value		13,300,000,000	13,800,000,000
Amount of difference between carrying value and fair value based on quoted market price		$ 2,000,000,000
Difference between carrying value and fair value percentage		15.00%
Berkadia Commercial Mortgage LLC, Pilot Travel Centers LLC, and Electric Transmission Texas, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method earnings (losses)		$ 631,000,000	683,000,000	$ 563,000,000
Equity method investments, carrying value		$ 4,000,000,000	$ 3,700,000,000
Berkadia Commercial Mortgage LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Commercial paper outstanding		$ 1,470,000,000
Berkadia Commercial Mortgage LLC [Member] | Commercial Paper [Member]
Schedule of Equity Method Investments [Line Items]
Maximum outstanding balance of commercial paper borrowings		$ 1,500,000,000
Berkadia Commercial Mortgage LLC [Member] | Jefferies Financial Group Inc. [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Electric Transmission Texas, LLC [Member] | Berkshire Hathaway Energy Company Subsidiary [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Electric Transmission Texas, LLC [Member] | American Electric Power [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%

Equity method investments - Fin

Equity method investments - Financial information (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 26, 2020	Dec. 31, 2019	Dec. 28, 2019	Dec. 31, 2018	Dec. 29, 2018
Schedule of Equity Method Investments [Line Items]
Assets	$ 873,729				$ 817,729				$ 873,729		$ 817,729		$ 707,794
Liabilities	422,393				389,166				422,393		389,166
Sales	$ 64,381	$ 63,024	$ 56,840	$ 61,265	$ 65,368	$ 64,972	$ 63,598	$ 60,678	$ 245,510		$ 254,616		$ 247,837
The Kraft Heinz Company [Member]
Schedule of Equity Method Investments [Line Items]
Assets										$ 99,830		$ 101,450
Liabilities										49,587		49,701
Sales										26,185		24,977		$ 26,268
Net earnings (losses) attributable to Kraft Heinz common shareholders										$ 356		$ 1,935		$ (10,192)

Investment gains_losses (Detail

Investment gains/losses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Equity securities - Change in unrealized investment gains/losses during the year on securities held at the end of the period	$ 54,951	$ 69,581	$ (22,729)
Equity securities - Investment gains/losses during the year on securities sold	(14,036)	1,585	291
Equity securities - Investment gains/losses, total	40,915	71,166	(22,438)
Fixed maturity securities - Gross realized gains	56	87	480
Fixed maturity securities - Gross realized losses	(27)	(25)	(227)
Other	(39)	(105)	30
Investment gains/losses	$ 40,905	$ 71,123	$ (22,155)

Investment gains_losses - Narra

Investment gains/losses - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Sales of equity securities	$ 38,756	$ 14,336	$ 18,783
Taxable gains (loss) on sales of equity securities	$ 6,200	$ 3,200	$ 3,300

Loans and finance receivables_2

Loans and finance receivables (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Loans and finance receivables before allowances and discounts	$ 20,436	$ 18,199
Allowances for uncollectible loans	(712)	(167)	$ (177)
Unamortized acquisition discounts and points	(523)	(505)
Loans and finance receivables	$ 19,201	$ 17,527

Loans and finance receivables -

Loans and finance receivables - Schedule of reconciliation of allowance for credit losses on loans and finance receivables (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Allowance For Credit Loss [Abstract]
Balance at beginning of year	$ 167	$ 177
Adoption of ASC 326	486
Provision for credit losses	177	125
Charge-offs, net of recoveries	(118)	(135)
Balance at December 31	$ 712	$ 167

Loans and finance receivables_3

Loans and finance receivables - Narrative (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Seritage Growth Properties [Member] | Term Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loan facility amount	$ 2,000,000,000
Expiration date of term loan	Jul. 31, 2023
Outstanding loan balance	$ 1,600,000,000	$ 1,600,000,000
Lee Enterprises, Inc. [Member] | Term Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding loan balance	$ 524,000,000
Loans and Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of manufactured housing loan balances evaluated collectively for impairment	99.00%
Home Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percent of loan balances considered to be current as to payment status	97.00%

Loans and finance receivables_4

Loans and finance receivables - Summary of performing and non-performing home loans before discounts and allowances by year of loan origination (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, Total	$ 20,436	$ 18,199
Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2020	4,433
Loans and financing receivables by origination year, 2019	2,542
Loans and financing receivables by origination year, 2018	1,935
Loans and financing receivables by origination year, 2017	1,431
Loans and financing receivables by origination year, 2016	1,283
Loans and financing receivables by origination year, Prior	6,688
Loans and financing receivables by origination year, Total	18,312
Performing [Member] | Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2020	4,430
Loans and financing receivables by origination year, 2019	2,537
Loans and financing receivables by origination year, 2018	1,928
Loans and financing receivables by origination year, 2017	1,424
Loans and financing receivables by origination year, 2016	1,276
Loans and financing receivables by origination year, Prior	6,645
Loans and financing receivables by origination year, Total	18,240
Non-Performing [Member] | Manufactured Housing Loan Balances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and financing receivables by origination year, 2020	3
Loans and financing receivables by origination year, 2019	5
Loans and financing receivables by origination year, 2018	7
Loans and financing receivables by origination year, 2017	7
Loans and financing receivables by origination year, 2016	7
Loans and financing receivables by origination year, Prior	43
Loans and financing receivables by origination year, Total	$ 72

Other receivables (Detail)

Other receivables (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Insurance and Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Insurance premiums receivable	$ 14,025	$ 13,379
Reinsurance recoverables	4,805	4,470
Trade receivables	11,521	12,275
Other	2,637	2,712
Allowances for uncollectible accounts	(678)	(418)
Other receivables	32,310	32,418
Railroad, Utilities and Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	3,235	3,120
Other	438	388
Allowances for uncollectible accounts	(131)	(91)
Receivables	$ 3,542	$ 3,417

Other receivables - Narrative (

Other receivables - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Provisions for credit losses on receivables	$ 564	$ 363
Net charge-offs	$ 401	$ 350

Inventories (Detail)

Inventories (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Raw materials	$ 4,821	$ 4,492
Work in process and other	2,541	2,700
Finished manufactured goods	4,412	4,821
Goods acquired for resale	7,434	7,839
Total inventory	$ 19,208	$ 19,852

Property, plant and equipment (

Property, plant and equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Insurance and Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 43,817	$ 42,210
Property, plant and equipment, accumulated depreciation	(22,617)	(20,772)
Total property, plant and equipment, net	21,200	21,438
Insurance and Other [Member] | Land, buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	13,799	13,259
Insurance and Other [Member] | Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	25,488	24,285
Insurance and Other [Member] | Furniture, fixtures and other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,530	4,666
Railroad [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	78,263	76,634
Property, plant and equipment, accumulated depreciation	(13,175)	(12,101)
Total property, plant and equipment, net	65,088	64,533
Railroad [Member] | Land, track structure and other roadway [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	63,824	62,404
Railroad [Member] | Locomotives, freight cars and other equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	13,523	13,482
Railroad [Member] | Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	916	748
Utilities and Energy [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	119,376	101,841
Property, plant and equipment, accumulated depreciation	(33,248)	(28,536)
Total property, plant and equipment, net	86,128	73,305
Utilities and Energy [Member] | Utility generation, transmission and distribution systems [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	86,730	81,127
Utilities and Energy [Member] | Interstate natural gas pipeline assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	16,667	8,165
Utilities and Energy [Member] | Independent power plants and other assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,671	8,817
Utilities and Energy [Member] | Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,308	3,732
Railroad, Utilities and Energy [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, net	$ 151,216	$ 137,838

Property, plant and equipment -

Property, plant and equipment - Depreciation expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 8,119	$ 7,566	$ 7,284
Insurance and Other [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	2,320	2,269	2,186
Railroad, Utilities and Energy [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 5,799	$ 5,297	$ 5,098

Equipment held for lease (Detai

Equipment held for lease (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	$ 22,474	$ 22,215
Equipment held for lease, accumulated depreciation	(7,873)	(7,150)
Equipment held for lease, net	14,601	15,065
Railcars [Member]
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	9,402	9,260
Aircraft [Member]
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	8,204	8,093
Other [Member]
Property Subject to or Available for Operating Lease [Line Items]
Equipment held for lease, gross	$ 4,868	$ 4,862

Equipment held for lease - Narr

Equipment held for lease - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Depreciation expense for equipment held for lease	$ 1,200	$ 1,181	$ 1,102

Equipment held for lease - Summ

Equipment held for lease - Summary of fixed and variable operating lease revenues (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating Leases Lease Income [Abstract]
Fixed lease revenue	$ 4,262	$ 4,415
Variable lease revenue	947	1,441
Total	$ 5,209	$ 5,856

Equipment held for lease - Su_2

Equipment held for lease - Summary of remaining operating lease receipts (Detail) $ in Millions	Dec. 31, 2020USD ($)
Lessor Operating Lease Payments Fiscal Year Maturity [Abstract]
2021	$ 2,618
2022	1,962
2023	1,429
2024	905
2025	443
Thereafter	387
Total	$ 7,744

Leases - Narrative (Detail)

Leases - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating leases, right of use assets		$ 5,579	$ 5,941
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]		us-gaap:OtherAssets	us-gaap:OtherAssets
Operating lease liabilities		$ 5,469	$ 5,882
Operating Lease, Liability, Statement of Financial Position [Extensible List]		us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent	us-gaap:AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
Weighted average lease term		7 years 3 months 18 days	7 years 8 months 12 days
Weighted average discount rate used to measure lease liabilities		3.60%	3.80%
Operating lease expense	$ 1,649

Leases - Summary of remaining o

Leases - Summary of remaining operating lease payments (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating Lease Liabilities, Payments Due [Abstract]
Year 1	$ 1,342	$ 1,374
Year 2	1,111	1,183
Year 3	905	950
Year 4	725	764
Year 5	544	620
Thereafter	1,691	1,988
Total lease payments	6,318	6,879
Amount representing interest	(849)	(997)
Lease liabilities	$ 5,469	$ 5,882

Leases - Components of operatin

Leases - Components of operating lease costs (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease Cost [Abstract]
Operating lease cost	$ 1,413	$ 1,459
Short-term lease cost	145	178
Variable lease cost	228	276
Sublease income	(10)	(24)
Total lease cost	$ 1,776	$ 1,889

Goodwill and other intangible_3

Goodwill and other intangible assets - Goodwill (Detail) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Jun. 30, 2020	Dec. 31, 2020		Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Balance at beginning of year			$ 81,882	[1]	$ 81,025
Acquisitions of businesses			1,758		890
Impairment charges		$ (10,000)	(10,033)		(90)
Other, including foreign currency translation			127		57
Balance at end of year	[1]		$ 73,734		$ 81,882
[1]	Net of accumulated goodwill impairments of $11.0 billion as of December 31, 2020 and $1.1 billion as of December 31, 2019.

Goodwill and other intangible_4

Goodwill and other intangible assets - Goodwill (Parenthetical) (Detail) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Accumulated goodwill impairments	$ 11	$ 1.1

Goodwill and other intangible_5

Goodwill and other intangible assets - Intangible assets (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Insurance and Other [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 40,685	$ 41,153
Accumulated amortization	11,223	10,102
Railroad, Utilities and Energy [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,681	1,003
Accumulated amortization	459	408
Trademarks and trade names [Member] | Insurance and Other [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	5,206	5,286
Accumulated amortization	779	759
Customer relationships [Member] | Insurance and Other [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	27,374	27,943
Accumulated amortization	5,756	5,025
Customer relationships [Member] | Railroad, Utilities and Energy [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	678	678
Accumulated amortization	361	324
Other intangible assets [Member] | Insurance and Other [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	3,339	3,364
Accumulated amortization	1,375	1,286
Trademarks, Trade Names and Other [Member] | Railroad, Utilities and Energy [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,003	325
Accumulated amortization	98	84
Patents and technology [Member] | Insurance and Other [Member]
Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]
Gross carrying amount	4,766	4,560
Accumulated amortization	$ 3,313	$ 3,032

Goodwill and other intangible_6

Goodwill and other intangible assets - Intangible assets - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Intangible asset amortization expense		$ 1,277	$ 1,317	$ 1,393
Estimated amortization expense - 2021		1,262
Estimated amortization expense - 2022		1,190
Estimated amortization expense - 2023		1,108
Estimated amortization expense - 2024		986
Estimated amortization expense - 2025		906
Intangible assets with indefinite lives, excluding goodwill		18,300	19,000
Pre tax goodwill impairment	$ 10,000	$ 10,033	$ 90
Pre tax intangible assets impairment charges	638
PCC [Member]
Goodwill [Line Items]
Pre tax impairment charges	10,000
Goodwill and indefinite-lived intangible assets	$ 31,000

Derivative contracts (Detail)

Derivative contracts (Detail) - Not Designated as Hedging Instrument [Member] - Equity Index Put Options [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative contract liabilities	$ 1,065	$ 968
Notional value	10,991	14,385
Intrinsic value	$ 727	$ 397
Weighted average remaining life (in years)	1 year 2 months 12 days	1 year 9 months 18 days

Derivative contracts - Narrativ

Derivative contracts - Narrative (Detail) - Not Designated as Hedging Instrument [Member] - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Collateral posting requirements under contracts with collateral provisions	$ 0
Equity Index Put Options [Member]
Derivative [Line Items]
Derivative maturity month and year	2023-02
Premiums received at contract inception dates	$ 1,900,000,000
Derivative contract gains (losses)	$ (159,000,000)	$ 1,484,000,000	$ (300,000,000)
Equity Index Put Options [Member] | Maximum [Member]
Derivative [Line Items]
Derivative inception month and year	2008-03

Unpaid losses and loss adjust_3

Unpaid losses and loss adjustment expenses - Reconciliation of changes in claim liabilities (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Gross liabilities at beginning of year	$ 73,019	$ 68,458	$ 61,122
Reinsurance recoverable on unpaid losses at beginning of year	(2,855)	(3,060)	(3,201)
Net liabilities at beginning of year	70,164	65,398	57,921
Net liabilities at end of year	76,942	70,164	65,398
Reinsurance recoverable on unpaid losses at end of year	2,912	2,855	3,060
Gross liabilities at end of year	79,854	73,019	68,458
Property and Casualty Insurance and Reinsurance, Excluding Retroactive Reinsurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, current accident year events	43,400	43,335	39,876
Incurred losses and loss adjustment expenses, prior accident years' events	(356)	(752)	(1,406)
Total	43,044	42,583	38,470
Paid losses and loss adjustment expenses, current accident year events	(17,884)	(19,482)	(18,391)
Paid losses and loss adjustment expenses, prior accident years' events	(18,862)	(17,642)	(15,452)
Total	(36,746)	(37,124)	(33,843)
Foreign currency translation adjustment	$ 480	(23)	(331)
Business acquisition (disposition)		$ (670)	$ 3,181

Unpaid losses and loss adjust_4

Unpaid losses and loss adjustment expenses - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property and Casualty Reinsurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses for (reductions of) prior years' accident events	$ 162	$ (295)	$ (469)
Property and Casualty Insurance and Reinsurance, Excluding Retroactive Reinsurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses with respect to current accident year events	43,400	43,335	39,876
Incurred losses and loss adjustment expenses for (reductions of) prior years' accident events	$ (356)	$ (752)	$ (1,406)
Prior years' losses incurred as a percentage of net liabilities	0.50%	1.10%	2.40%
Liabilities included amounts for environmental, asbestos and latent injury claims, net of reinsurance	$ 2,100	$ 1,700
Property and Casualty Insurance and Reinsurance, Excluding Retroactive Reinsurance [Member] | Significant Catastrophe Events [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses with respect to current accident year events	950	1,000	$ 1,600
Primary Insurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses for (reductions of) prior years' accident events	$ (518)	$ (457)	$ (937)

Unpaid losses and loss adjust_5

Unpaid losses and loss adjustment expenses - Reconciliation of unpaid losses and allocated loss adjustment expenses to balance sheet liability (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Reinsurance recoverable	$ 2,912	$ 2,855	$ 3,060	$ 3,201
Unpaid losses and loss adjustment expenses	79,854	$ 73,019	$ 68,458	$ 61,122
Insurance Group [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and ALAE, net	72,640
Reinsurance recoverable	2,824
Unpaid unallocated loss adjustment expenses	2,671
Other unpaid losses and loss adjustment expenses	1,719
Unpaid losses and loss adjustment expenses	79,854
Insurance Group [Member] | GEICO [Member] | Physical Damage [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and ALAE, net	524
Insurance Group [Member] | GEICO [Member] | Auto Liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and ALAE, net	18,755
Reinsurance recoverable	1,109
Insurance Group [Member] | Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and ALAE, net	7,897
Reinsurance recoverable	49
Insurance Group [Member] | Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and ALAE, net	11,294
Reinsurance recoverable	621
Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member] | Property [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and ALAE, net	11,280
Reinsurance recoverable	181
Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Unpaid losses and ALAE, net	22,890
Reinsurance recoverable	$ 864

Unpaid losses and loss adjust_6

Unpaid losses and loss adjustment expenses - Incurred and paid losses and allocated loss adjustment expenses (Detail) - Insurance Group [Member] Claim in Thousands, $ in Millions	Dec. 31, 2020USD ($)Claim	Dec. 31, 2019USD ($)		Dec. 31, 2018USD ($)	[1]	Dec. 31, 2017USD ($)	[1]	Dec. 31, 2016USD ($)	[1]	Dec. 31, 2015USD ($)	[1]	Dec. 31, 2014USD ($)	[1]	Dec. 31, 2013USD ($)	[1]	Dec. 31, 2012USD ($)	[1]	Dec. 31, 2011USD ($)	[1]
Claims Development [Line Items]
Unpaid losses and ALAE, net	$ 72,640
GEICO [Member] | Physical Damage [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	17,523
Cumulative Paid Losses and ALAE	17,023
Unpaid losses and ALAE, net	524
GEICO [Member] | Physical Damage [Member] | 2019 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	8,920	$ 9,020
Cumulative Paid Losses and ALAE	8,905	8,678
IBNR and Case Development Liabilities	$ 69
Cumulative Number of Reported Claims | Claim	8,929
GEICO [Member] | Physical Damage [Member] | 2020 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 8,603
Cumulative Paid Losses and ALAE	8,118
IBNR and Case Development Liabilities	$ 296
Cumulative Number of Reported Claims | Claim	7,794
GEICO [Member] | Physical Damage [Member] | 2019-2020 [Member]
Claims Development [Line Items]
Unpaid losses and ALAE, net	$ 500
GEICO [Member] | Physical Damage [Member] | Shortduration Insurance Contracts Accident Years Before 2019
Claims Development [Line Items]
Net unpaid losses and ALAE for accident years before earliest accident year presented	24
GEICO [Member] | Auto Liability [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	72,322
Cumulative Paid Losses and ALAE	54,171
Unpaid losses and ALAE, net	18,755
GEICO [Member] | Auto Liability [Member] | 2016 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	12,198	12,178	[1]	$ 12,149		$ 12,184		$ 11,800
Cumulative Paid Losses and ALAE	11,718	11,294	[1]	10,330		8,716		5,069
IBNR and Case Development Liabilities	$ 222
Cumulative Number of Reported Claims | Claim	2,451
GEICO [Member] | Auto Liability [Member] | 2017 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 13,824	13,888	[1]	13,864		14,095
Cumulative Paid Losses and ALAE	12,729	11,799	[1]	9,944		5,806
IBNR and Case Development Liabilities	$ 502
Cumulative Number of Reported Claims | Claim	2,639
GEICO [Member] | Auto Liability [Member] | 2019 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 16,678	16,901	[1]
Cumulative Paid Losses and ALAE	11,671	6,742	[1]
IBNR and Case Development Liabilities	$ 2,905
Cumulative Number of Reported Claims | Claim	2,749
GEICO [Member] | Auto Liability [Member] | 2020 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 14,637
Cumulative Paid Losses and ALAE	5,395
IBNR and Case Development Liabilities	$ 4,482
Cumulative Number of Reported Claims | Claim	1,945
GEICO [Member] | Auto Liability [Member] | 2018 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 14,985	15,226	[1]	15,383
Cumulative Paid Losses and ALAE	12,658	10,772	[1]	6,218
IBNR and Case Development Liabilities	$ 1,163
Cumulative Number of Reported Claims | Claim	2,702
GEICO [Member] | Auto Liability [Member] | 2016-2020 [Member]
Claims Development [Line Items]
Unpaid losses and ALAE, net	$ 18,151
GEICO [Member] | Auto Liability [Member] | Before 2016 [Member]
Claims Development [Line Items]
Net unpaid losses and ALAE for accident years before earliest accident year presented	604
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	13,032
Cumulative Paid Losses and ALAE	5,518
Unpaid losses and ALAE, net	7,897
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2011 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	972	968	[1]	1,004		1,050		1,115		$ 1,173		$ 1,262		$ 1,321		$ 1,334		$ 1,346
Cumulative Paid Losses and ALAE	842	822	[1]	767		711		632		517		356		200		82		16
IBNR and Case Development Liabilities	$ 39
Cumulative Number of Reported Claims | Claim	11
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2012 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 988	998	[1]	1,035		1,078		1,168		1,223		1,277		1,306		1,336
Cumulative Paid Losses and ALAE	830	789	[1]	725		642		522		377		218		93		15
IBNR and Case Development Liabilities	$ 53
Cumulative Number of Reported Claims | Claim	11
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2013 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 985	1,019	[1]	1,086		1,127		1,195		1,261		1,296		1,328
Cumulative Paid Losses and ALAE	793	743	[1]	635		518		368		219		90		15
IBNR and Case Development Liabilities	$ 65
Cumulative Number of Reported Claims | Claim	11
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2014 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,061	1,127	[1]	1,218		1,246		1,305		1,375		1,370
Cumulative Paid Losses and ALAE	752	671	[1]	540		396		238		106		21
IBNR and Case Development Liabilities	$ 129
Cumulative Number of Reported Claims | Claim	11
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2015 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,157	1,218	[1]	1,290		1,269		1,342		1,374
Cumulative Paid Losses and ALAE	663	543	[1]	382		218		108		23
IBNR and Case Development Liabilities	$ 202
Cumulative Number of Reported Claims | Claim	12
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2016 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,341	1,394	[1]	1,414		1,416		1,392
Cumulative Paid Losses and ALAE	620	461	[1]	274		115		22
IBNR and Case Development Liabilities	$ 286
Cumulative Number of Reported Claims | Claim	14
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2017 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,474	1,495	[1]	1,499		1,466
Cumulative Paid Losses and ALAE	457	300	[1]	128		27
IBNR and Case Development Liabilities	$ 494
Cumulative Number of Reported Claims | Claim	20
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2019 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,691	1,670	[1]
Cumulative Paid Losses and ALAE	160	39	[1]
IBNR and Case Development Liabilities	$ 1,204
Cumulative Number of Reported Claims | Claim	17
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2020 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,704
Cumulative Paid Losses and ALAE	34
IBNR and Case Development Liabilities	$ 1,529
Cumulative Number of Reported Claims | Claim	13
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | 2018 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,659	1,650	[1]	1,602
Cumulative Paid Losses and ALAE	367	166	[1]	35
IBNR and Case Development Liabilities	$ 780
Cumulative Number of Reported Claims | Claim	22
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | Shortduration Insurance Contracts Accident Years 2011 Through 2020
Claims Development [Line Items]
Unpaid losses and ALAE, net	$ 7,514
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member] | Shortduration Insurance Contracts Accident Years Before 2011
Claims Development [Line Items]
Net unpaid losses and ALAE for accident years before earliest accident year presented	383
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	23,007
Cumulative Paid Losses and ALAE	12,099
Unpaid losses and ALAE, net	11,294
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2011 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	576	591	[1]	596		607		618		621		624		675		675		738
Cumulative Paid Losses and ALAE	519	512	[1]	505		496		481		453		403		333		220		109
IBNR and Case Development Liabilities	$ 39
Cumulative Number of Reported Claims | Claim	46
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2012 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 718	736	[1]	750		762		780		791		837		850		873
Cumulative Paid Losses and ALAE	634	626	[1]	611		592		560		501		414		299		116
IBNR and Case Development Liabilities	$ 53
Cumulative Number of Reported Claims | Claim	53
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2013 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,028	1,050	[1]	1,072		1,096		1,127		1,178		1,228		1,258
Cumulative Paid Losses and ALAE	874	858	[1]	835		793		725		609		422		177
IBNR and Case Development Liabilities	$ 120
Cumulative Number of Reported Claims | Claim	67
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2014 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,477	1,497	[1]	1,482		1,548		1,614		1,638		1,743
Cumulative Paid Losses and ALAE	1,214	1,176	[1]	1,111		1,007		800		557		239
IBNR and Case Development Liabilities	$ 190
Cumulative Number of Reported Claims | Claim	90
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2015 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 1,997	2,025	[1]	2,014		2,042		2,127		2,169
Cumulative Paid Losses and ALAE	1,570	1,488	[1]	1,289		1,017		700		289
IBNR and Case Development Liabilities	$ 267
Cumulative Number of Reported Claims | Claim	111
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2016 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 2,365	2,325	[1]	2,359		2,422		2,511
Cumulative Paid Losses and ALAE	1,661	1,461	[1]	1,148		775		329
IBNR and Case Development Liabilities	$ 470
Cumulative Number of Reported Claims | Claim	115
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2017 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 2,843	2,842	[1]	2,907		3,044
Cumulative Paid Losses and ALAE	1,771	1,434	[1]	1,003		441
IBNR and Case Development Liabilities	$ 691
Cumulative Number of Reported Claims | Claim	138
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2019 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 4,102	4,074	[1]
Cumulative Paid Losses and ALAE	1,478	682	[1]
IBNR and Case Development Liabilities	$ 1,788
Cumulative Number of Reported Claims | Claim	170
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2020 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 4,421
Cumulative Paid Losses and ALAE	695
IBNR and Case Development Liabilities	$ 2,987
Cumulative Number of Reported Claims | Claim	120
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | 2018 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	$ 3,480	3,412	[1]	3,544
Cumulative Paid Losses and ALAE	1,683	1,198	[1]	538
IBNR and Case Development Liabilities	$ 1,152
Cumulative Number of Reported Claims | Claim	160
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | Shortduration Insurance Contracts Accident Years 2011 Through 2020
Claims Development [Line Items]
Unpaid losses and ALAE, net	$ 10,908
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member] | Shortduration Insurance Contracts Accident Years Before 2011
Claims Development [Line Items]
Net unpaid losses and ALAE for accident years before earliest accident year presented	386
Berkshire Hathaway Reinsurance Group [Member] | Property [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	36,343
Cumulative Paid Losses and ALAE	25,398
Unpaid losses and ALAE, net	11,280
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2011 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	3,616	3,627	[1]	3,638		3,654		3,672		3,707		3,711		3,804		4,095		4,111
Cumulative Paid Losses and ALAE	3,507	3,493	[1]	3,474		3,429		3,387		3,304		3,188		2,917		2,259		609
IBNR and Case Development Liabilities	30
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2012 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	2,305	2,315	[1]	2,329		2,348		2,351		2,403		2,644		2,846		3,153
Cumulative Paid Losses and ALAE	2,199	2,181	[1]	2,135		2,117		2,040		1,950		1,813		1,232		262
IBNR and Case Development Liabilities	35
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2013 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	2,504	2,518	[1]	2,570		2,631		2,653		2,745		3,093		3,255
Cumulative Paid Losses and ALAE	2,376	2,347	[1]	2,307		2,226		2,105		1,906		1,459		526
IBNR and Case Development Liabilities	45
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2014 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	2,021	2,050	[1]	2,123		2,178		2,322		2,436		2,648
Cumulative Paid Losses and ALAE	1,858	1,829	[1]	1,779		1,713		1,574		1,249		467
IBNR and Case Development Liabilities	48
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2015 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	3,000	2,976	[1]	2,979		2,577		3,135		3,287
Cumulative Paid Losses and ALAE	2,453	2,271	[1]	2,166		1,969		1,614		581
IBNR and Case Development Liabilities	143
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2016 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	3,616	3,614	[1]	3,646		3,923		3,293
Cumulative Paid Losses and ALAE	2,923	2,670	[1]	2,208		1,811		709
IBNR and Case Development Liabilities	218
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2017 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	4,727	4,837	[1]	4,986		5,291
Cumulative Paid Losses and ALAE	3,972	3,660	[1]	2,734		1,028
IBNR and Case Development Liabilities	187
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2019 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	4,299	4,146	[1]
Cumulative Paid Losses and ALAE	2,282	751	[1]
IBNR and Case Development Liabilities	952
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2020 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	5,858
Cumulative Paid Losses and ALAE	960
IBNR and Case Development Liabilities	3,129
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | 2018 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	4,397	4,524	[1]	4,426
Cumulative Paid Losses and ALAE	2,868	2,341	[1]	915
IBNR and Case Development Liabilities	678
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | Shortduration Insurance Contracts Accident Years 2011 Through 2020
Claims Development [Line Items]
Unpaid losses and ALAE, net	10,945
Berkshire Hathaway Reinsurance Group [Member] | Property [Member] | Shortduration Insurance Contracts Accident Years Before 2011
Claims Development [Line Items]
Net unpaid losses and ALAE for accident years before earliest accident year presented	335
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	26,307
Cumulative Paid Losses and ALAE	12,295
Unpaid losses and ALAE, net	22,890
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2011 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	2,255	2,272	[1]	2,307		2,346		2,354		2,447		2,536		2,595		2,726		2,635
Cumulative Paid Losses and ALAE	1,776	1,748	[1]	1,713		1,673		1,595		1,501		1,412		1,169		824		$ 294
IBNR and Case Development Liabilities	279
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2012 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	2,581	2,588	[1]	2,645		2,712		2,827		2,899		2,837		3,002		2,820
Cumulative Paid Losses and ALAE	1,883	1,825	[1]	1,764		1,664		1,539		1,381		1,150		757		$ 312
IBNR and Case Development Liabilities	317
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2013 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	1,892	1,964	[1]	2,060		2,114		2,170		2,328		2,298		2,160
Cumulative Paid Losses and ALAE	1,273	1,215	[1]	1,155		1,052		947		818		530		$ 294
IBNR and Case Development Liabilities	387
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2014 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	1,970	1,980	[1]	1,944		2,030		2,068		2,099		1,900
Cumulative Paid Losses and ALAE	1,119	974	[1]	889		765		655		488		$ 153
IBNR and Case Development Liabilities	537
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2015 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	1,870	1,908	[1]	2,035		2,137		2,109		1,902
Cumulative Paid Losses and ALAE	1,029	938	[1]	846		725		500		$ 199
IBNR and Case Development Liabilities	455
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2016 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	1,922	2,003	[1]	2,047		2,138		1,928
Cumulative Paid Losses and ALAE	972	874	[1]	742		563		$ 255
IBNR and Case Development Liabilities	555
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2017 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	2,494	2,588	[1]	2,711		2,216
Cumulative Paid Losses and ALAE	1,282	830	[1]	574		$ 233
IBNR and Case Development Liabilities	762
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2019 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	3,931	3,455	[1]
Cumulative Paid Losses and ALAE	906	356	[1]
IBNR and Case Development Liabilities	1,924
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2020 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	3,883
Cumulative Paid Losses and ALAE	406
IBNR and Case Development Liabilities	2,754
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | 2018 [Member]
Claims Development [Line Items]
Incurred Losses and ALAE	3,509	3,585	[1]	2,948
Cumulative Paid Losses and ALAE	1,649	$ 875	[1]	$ 267
IBNR and Case Development Liabilities	1,183
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | Shortduration Insurance Contracts Accident Years 2011 Through 2020
Claims Development [Line Items]
Unpaid losses and ALAE, net	14,012
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member] | Shortduration Insurance Contracts Accident Years Before 2011
Claims Development [Line Items]
Net unpaid losses and ALAE for accident years before earliest accident year presented	$ 8,878
[1]	Unaudited required supplemental information

Unpaid losses and loss adjust_7

Unpaid losses and loss adjustment expenses - Average historical claims duration (Detail) - Insurance Group [Member]	Dec. 31, 2020
GEICO [Member] | Physical Damage [Member]
Shortduration Insurance Contracts Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses, net of reinsurance, year one	97.00%
Average annual percentage payout of incurred losses, net of reinsurance, year two	2.00%
GEICO [Member] | Auto Liability [Member]
Shortduration Insurance Contracts Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses, net of reinsurance, year one	42.00%
Average annual percentage payout of incurred losses, net of reinsurance, year two	29.00%
Average annual percentage payout of incurred losses, net of reinsurance, year three	13.00%
Average annual percentage payout of incurred losses, net of reinsurance, year four	7.00%
Average annual percentage payout of incurred losses, net of reinsurance, year five	4.00%
Berkshire Hathaway Primary Group [Member] | Medical Professional Liability [Member]
Shortduration Insurance Contracts Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses, net of reinsurance, year one	2.00%
Average annual percentage payout of incurred losses, net of reinsurance, year two	7.00%
Average annual percentage payout of incurred losses, net of reinsurance, year three	12.00%
Average annual percentage payout of incurred losses, net of reinsurance, year four	14.00%
Average annual percentage payout of incurred losses, net of reinsurance, year five	14.00%
Average annual percentage payout of incurred losses, net of reinsurance, year six	12.00%
Average annual percentage payout of incurred losses, net of reinsurance, year seven	9.00%
Average annual percentage payout of incurred losses, net of reinsurance, year eight	6.00%
Average annual percentage payout of incurred losses, net of reinsurance, year nine	5.00%
Average annual percentage payout of incurred losses, net of reinsurance, year ten	2.00%
Berkshire Hathaway Primary Group [Member] | Workers' Compensation and Other Casualty [Member]
Shortduration Insurance Contracts Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses, net of reinsurance, year one	16.00%
Average annual percentage payout of incurred losses, net of reinsurance, year two	21.00%
Average annual percentage payout of incurred losses, net of reinsurance, year three	16.00%
Average annual percentage payout of incurred losses, net of reinsurance, year four	13.00%
Average annual percentage payout of incurred losses, net of reinsurance, year five	8.00%
Average annual percentage payout of incurred losses, net of reinsurance, year six	4.00%
Average annual percentage payout of incurred losses, net of reinsurance, year seven	3.00%
Average annual percentage payout of incurred losses, net of reinsurance, year eight	2.00%
Average annual percentage payout of incurred losses, net of reinsurance, year nine	1.00%
Average annual percentage payout of incurred losses, net of reinsurance, year ten	1.00%
Berkshire Hathaway Reinsurance Group [Member] | Property [Member]
Shortduration Insurance Contracts Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses, net of reinsurance, year one	19.00%
Average annual percentage payout of incurred losses, net of reinsurance, year two	37.00%
Average annual percentage payout of incurred losses, net of reinsurance, year three	17.00%
Average annual percentage payout of incurred losses, net of reinsurance, year four	8.00%
Average annual percentage payout of incurred losses, net of reinsurance, year five	4.00%
Average annual percentage payout of incurred losses, net of reinsurance, year six	4.00%
Average annual percentage payout of incurred losses, net of reinsurance, year seven	1.00%
Average annual percentage payout of incurred losses, net of reinsurance, year eight	2.00%
Average annual percentage payout of incurred losses, net of reinsurance, year nine	1.00%
Average annual percentage payout of incurred losses, net of reinsurance, year ten	0.00%
Berkshire Hathaway Reinsurance Group [Member] | Casualty [Member]
Shortduration Insurance Contracts Historical Claims Duration [Line Items]
Average annual percentage payout of incurred losses, net of reinsurance, year one	11.00%
Average annual percentage payout of incurred losses, net of reinsurance, year two	16.00%
Average annual percentage payout of incurred losses, net of reinsurance, year three	14.00%
Average annual percentage payout of incurred losses, net of reinsurance, year four	9.00%
Average annual percentage payout of incurred losses, net of reinsurance, year five	5.00%
Average annual percentage payout of incurred losses, net of reinsurance, year six	5.00%
Average annual percentage payout of incurred losses, net of reinsurance, year seven	5.00%
Average annual percentage payout of incurred losses, net of reinsurance, year eight	2.00%
Average annual percentage payout of incurred losses, net of reinsurance, year nine	2.00%
Average annual percentage payout of incurred losses, net of reinsurance, year ten	1.00%

Retroactive reinsurance contr_3

Retroactive reinsurance contracts - Reconciliation of changes in claim liabilities and deferred charge assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability for Claims and Claims Adjustment Expense [Line Items]
Unpaid losses and loss adjustment expenses, beginning of year	$ 42,441	$ 41,834	$ 42,937
Unpaid losses and loss adjustment expenses, end of year	40,966	42,441	41,834
Deferred charges reinsurance assumed, beginning of year	(13,747)	(14,104)	(15,278)
Deferred charges reinsurance assumed, end of year	(12,441)	(13,747)	(14,104)
Retroactive Reinsurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses, prior accident years' events	907	1,188	919
Total incurred losses and loss adjustment expenses	907	1,873	1,436
Unpaid Losses and Loss Adjustment Expenses [Member] | Retroactive Reinsurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses with respect to current accident year events		1,138	603
Incurred losses and loss adjustment expenses, prior accident years' events	(399)	378	(341)
Total incurred losses and loss adjustment expenses	(399)	1,516	262
Paid losses and loss adjustment expenses	(1,076)	(909)	(1,365)
Deferred Charges Reinsurance Assumed [Member] | Retroactive Reinsurance [Member]
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred losses and loss adjustment expenses with respect to current accident year events		(453)	(86)
Incurred losses and loss adjustment expenses, prior accident years' events	1,306	810	1,260
Total incurred losses and loss adjustment expenses	$ 1,306	$ 357	$ 1,174

Retroactive reinsurance contr_4

Retroactive reinsurance contracts - Narrative (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effects of Reinsurance [Line Items]
Unpaid losses and loss adjustment expenses under retroactive reinsurance contracts	$ 40,966,000,000	$ 42,441,000,000	$ 41,834,000,000	$ 42,937,000,000
Deferred charges under retroactive reinsurance contracts	12,441,000,000	13,747,000,000	14,104,000,000	$ 15,278,000,000
Retroactive Reinsurance [Member]
Effects of Reinsurance [Line Items]
Incurred losses and loss adjustment expenses, prior accident years' events	907,000,000	1,188,000,000	$ 919,000,000
Liabilities for environmental, asbestos and latent injury claims	12,500,000,000	12,900,000,000
AIG [Member] | Retroactive Reinsurance [Member]
Effects of Reinsurance [Line Items]
Unpaid losses and loss adjustment expenses under retroactive reinsurance contracts	$ 17,700,000,000	18,200,000,000
Percentage of losses and allocated loss adjustment expenses reinsured in excess of retained amount	80.00%
Losses and allocated loss adjustment expenses retained amount	$ 25,000,000,000
Deferred charges under retroactive reinsurance contracts	5,400,000,000	$ 6,300,000,000
AIG [Member] | Maximum [Member] | Retroactive Reinsurance [Member]
Effects of Reinsurance [Line Items]
Losses and allocated loss adjustment expenses reinsured in excess of retained amount	$ 25,000,000,000

Notes payable and other borro_3

Notes payable and other borrowings (Detail) € in Millions, £ in Millions, $ in Millions, ¥ in Billions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2020JPY (¥)	Dec. 31, 2020GBP (£)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Notes payable and other borrowings		€ 6,850	¥ 625.5	£ 1,750
Principal payments on debt - 2021	$ 9,398
Principal payments on debt - 2022	4,998
Principal payments on debt - 2023	10,813
Principal payments on debt - 2024	6,308
Principal payments on debt - 2025	6,594
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	41,522				$ 37,590
Principal payments on debt - 2021	4,354
Principal payments on debt - 2022	1,593
Principal payments on debt - 2023	6,021
Principal payments on debt - 2024	2,343
Principal payments on debt - 2025	2,817
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	75,373				65,778
Principal payments on debt - 2021	5,044
Principal payments on debt - 2022	3,405
Principal payments on debt - 2023	4,792
Principal payments on debt - 2024	3,965
Principal payments on debt - 2025	3,777
Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	22,665				19,903
Principal payments on debt - 2021	2,172
Principal payments on debt - 2022	600
Principal payments on debt - 2023	4,633
Principal payments on debt - 2024	2,272
Principal payments on debt - 2025	1,801
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | U.S. Dollar Denominated [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 8,308				8,324
Weighted average interest rate, percentage	3.20%	3.20%	3.20%	3.20%
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | U.S. Dollar Denominated [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2021
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | U.S. Dollar Denominated [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2047
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Euro Denominated [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 8,326				7,641
Weighted average interest rate, percentage	1.00%	1.00%	1.00%	1.00%
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Euro Denominated [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2021
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Euro Denominated [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2035
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Japanese Yen Denominated [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 6,031				3,938
Weighted average interest rate, percentage	0.70%	0.70%	0.70%	0.70%
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Japanese Yen Denominated [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2023
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Japanese Yen Denominated [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2060
Subsidiaries [Member] | Insurance and Other [Member]
Debt Instrument [Line Items]
Other borrowings	$ 4,682				5,262
Short-term debt	$ 1,062				1,472
Weighted average interest rate, percentage	4.20%	4.20%	4.20%	4.20%
Short-term debt, weighted average interest rate	2.50%	2.50%	2.50%	2.50%
Subsidiaries [Member] | Insurance and Other [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2021
Subsidiaries [Member] | Insurance and Other [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2045
Subsidiaries [Member] | Insurance and Other [Member] | U.S. Dollar Denominated [Member] | Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 10,766				8,679
Weighted average interest rate, percentage	3.70%	3.70%	3.70%	3.70%
Subsidiaries [Member] | Insurance and Other [Member] | U.S. Dollar Denominated [Member] | Berkshire Hathaway Finance Corporation [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2021
Subsidiaries [Member] | Insurance and Other [Member] | U.S. Dollar Denominated [Member] | Berkshire Hathaway Finance Corporation [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2050
Subsidiaries [Member] | Insurance and Other [Member] | Great Britain Pound Denominated [Member] | Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 2,347				2,274
Weighted average interest rate, percentage	2.50%	2.50%	2.50%	2.50%
Subsidiaries [Member] | Insurance and Other [Member] | Great Britain Pound Denominated [Member] | Berkshire Hathaway Finance Corporation [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2039
Subsidiaries [Member] | Insurance and Other [Member] | Great Britain Pound Denominated [Member] | Berkshire Hathaway Finance Corporation [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2059
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Berkshire Hathaway Energy [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage	4.20%	4.20%	4.20%	4.20%
Senior unsecured debt	$ 13,447				8,581
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Berkshire Hathaway Energy [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2021
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Berkshire Hathaway Energy [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2051
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Berkshire Hathaway Energy Subsidiaries [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 36,420				30,772
Weighted average interest rate, percentage	4.10%	4.10%	4.10%	4.10%
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Berkshire Hathaway Energy Subsidiaries [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2021
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Berkshire Hathaway Energy Subsidiaries [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2064
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Short-term debt	$ 2,286				3,214
Short-term debt, weighted average interest rate	1.80%	1.80%	1.80%	1.80%
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Burlington Northern Santa Fe ("BNSF") and subsidiaries [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings	$ 23,220				$ 23,211
Weighted average interest rate, percentage	4.60%	4.60%	4.60%	4.60%
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Burlington Northern Santa Fe ("BNSF") and subsidiaries [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2021
Subsidiaries [Member] | Railroad, Utilities and Energy [Member] | Burlington Northern Santa Fe ("BNSF") and subsidiaries [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2097

Notes payable and other borro_4

Notes payable and other borrowings - Narrative (Detail) € in Millions, £ in Millions, $ in Millions, ¥ in Billions	1 Months Ended			12 Months Ended
	Apr. 30, 2020USD ($)	Apr. 30, 2020JPY (¥)	Mar. 31, 2020EUR (€)	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2020JPY (¥)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2020JPY (¥)	Dec. 31, 2020GBP (£)	Nov. 01, 2020USD ($)
Debt Instrument [Line Items]
Notes payable and other borrowings									€ 6,850	¥ 625.5	£ 1,750
Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings				$ 1,151			$ 758	$ 1,563
Gain (loss) attributable to changes in foreign currency exchange rates				(970)			193	366
Notes payable and other borrowings				22,665			19,903
Subsidiaries [Member] | Berkshire Hathaway Energy and Subsidiaries [Member] | Dominion Pipeline Business [Member]
Debt Instrument [Line Items]
Business acquisition assumed debt												$ 5,600
Insurance and Other [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings				41,522			37,590
Insurance and Other [Member] | Berkshire Hathaway Inc. (Parent) [Member] | Subsidiaries Excluding Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Guarantee obligation				$ 1,200
Insurance and Other [Member] | Subsidiaries [Member]
Debt Instrument [Line Items]
Weighted average interest rate, percentage				4.20%					4.20%	4.20%	4.20%
Insurance and Other [Member] | Subsidiaries [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year				2021	2021	2021
Insurance and Other [Member] | Subsidiaries [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year				2045	2045	2045
Insurance and Other [Member] | Senior Notes [Member] | Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Gain (loss) attributable to changes in foreign currency exchange rates				$ (1,000)			192	$ 366
Insurance and Other [Member] | Senior Notes [Member] | Subsidiaries [Member] | Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Repayments of borrowings				900
Principal amount of debt issued				$ 3,000
Insurance and Other [Member] | Senior Notes [Member] | Notes Due 2025 at 0.0% [Member] | Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Repayments of borrowings | €			€ 1,000		€ 1,000
Principal amount of debt issued | €			€ 1,000		€ 1,000
Debt instrument, interest rate, stated percentage			0.00%	0.00%					0.00%	0.00%	0.00%
Debt maturity year			2025	2025	2025	2025
Insurance and Other [Member] | Senior Notes [Member] | Debt Due 2023 To 2060 [Member] | Berkshire Hathaway Inc. (Parent) [Member]
Debt Instrument [Line Items]
Principal amount of debt issued	$ 1,800	¥ 195.5		$ 1,800		¥ 195.5
Weighted average interest rate, percentage	1.07%	1.07%		1.07%					1.07%	1.07%	1.07%
Insurance and Other [Member] | Senior Notes [Member] | Debt Due 2023 To 2060 [Member] | Berkshire Hathaway Inc. (Parent) [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt maturity year	2023	2023		2023	2023	2023
Insurance and Other [Member] | Senior Notes [Member] | Debt Due 2023 To 2060 [Member] | Berkshire Hathaway Inc. (Parent) [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt maturity year	2060	2060		2060	2060	2060
Insurance and Other [Member] | Senior Notes [Member] | Notes Due 2030 at 1.45% [Member] | Subsidiaries [Member] | Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				$ 750
Debt instrument, interest rate, stated percentage				1.45%					1.45%	1.45%	1.45%
Debt maturity year				2030	2030	2030
Insurance and Other [Member] | Senior Notes [Member] | Notes Due 2030 at 1.85% [Member] | Subsidiaries [Member] | Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				$ 500
Debt instrument, interest rate, stated percentage				1.85%					1.85%	1.85%	1.85%
Debt maturity year				2030	2030	2030
Insurance and Other [Member] | Senior Notes [Member] | Notes Due 2050 at 2.85% [Member] | Subsidiaries [Member] | Berkshire Hathaway Finance Corporation [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				$ 1,750
Debt instrument, interest rate, stated percentage				2.85%					2.85%	2.85%	2.85%
Debt maturity year				2050	2050	2050
Railroad, Utilities and Energy [Member]
Debt Instrument [Line Items]
Notes payable and other borrowings				$ 75,373			$ 65,778
Railroad, Utilities and Energy [Member] | Subsidiaries [Member] | Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Repayments of borrowings				3,200
Railroad, Utilities and Energy [Member] | Debt Due 2025 To 2062 [Member] | Subsidiaries [Member] | Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Principal amount of debt issued				$ 7,600
Weighted average interest rate, percentage				3.20%					3.20%	3.20%	3.20%
Railroad, Utilities and Energy [Member] | Debt Due 2025 To 2062 [Member] | Subsidiaries [Member] | Minimum [Member] | Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year				2025	2025	2025
Railroad, Utilities and Energy [Member] | Debt Due 2025 To 2062 [Member] | Subsidiaries [Member] | Maximum [Member] | Berkshire Hathaway Energy and Subsidiaries [Member]
Debt Instrument [Line Items]
Debt maturity year				2062	2062	2062
Railroad, Utilities and Energy [Member] | Senior Unsecured Debenture [Member] | Debentures Due 2051 [Member] | Subsidiaries [Member] | BNSF [Member]
Debt Instrument [Line Items]
Repayments of borrowings				$ 570
Principal amount of debt issued				$ 575
Debt instrument, interest rate, stated percentage				3.05%					3.05%	3.05%	3.05%
Debt maturity year				2051	2051	2051

Notes payable and other borro_5

Notes payable and other borrowings - Credit agreements - Narrative (Detail) - Line of Credit and Commercial Paper Facilities [Member] - Subsidiaries [Member] $ in Billions	Dec. 31, 2020USD ($)
Line of Credit Facility [Line Items]
Unused lines of credit available	$ 9.3
Berkshire Hathaway Energy and Subsidiaries [Member]
Line of Credit Facility [Line Items]
Unused lines of credit available	$ 8.2

Income taxes - Liabilities (Det

Income taxes - Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Currently payable (receivable)	$ (276)	$ 24
Deferred	73,261	65,823
Other	1,113	952
Income taxes, principally deferred	$ 74,098	$ 66,799

Income taxes - Deferred taxes (

Income taxes - Deferred taxes (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax liabilities:
Investments – unrealized appreciation and cost basis differences	$ 40,181	$ 32,134
Deferred charges reinsurance assumed	2,613	2,890
Property, plant and equipment and equipment held for lease	30,203	29,388
Goodwill and other intangible assets	6,753	7,293
Other	3,736	3,144
Deferred tax liabilities	83,486	74,849
Deferred tax assets:
Unpaid losses and loss adjustment expenses	(1,135)	(1,086)
Unearned premiums	(900)	(853)
Accrued liabilities	(2,193)	(1,981)
Regulatory liabilities	(1,421)	(1,610)
Other	(4,576)	(3,496)
Deferred tax assets	(10,225)	(9,026)
Net deferred tax liability	$ 73,261	$ 65,823

Income taxes - Narrative (Detai

Income taxes - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Income Taxes [Line Items]
Statutory U.S. Corporate income tax rate	21.00%		35.00%
Open tax years	2012 2013
Unrecognized tax benefits	$ 1,113	$ 952
Unrecognized tax benefits that would impact effective tax rate	920
Tax Equity Investment Funds [Member]
Income Taxes [Line Items]
Income tax expense for uncertain tax positions	$ 60	$ 377
Tax Year 2012 [Member]
Income Taxes [Line Items]
Income tax examination, year under examination	2014
Tax Year 2016 [Member]
Income Taxes [Line Items]
Income tax examination, year under examination	2016

Income taxes - Income tax expen

Income taxes - Income tax expense components (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income tax expense:
Federal	$ 10,596	$ 19,069	$ (1,613)
State	1,086	625	175
Foreign	758	1,210	1,117
Total income taxes	12,440	20,904	(321)
Income tax expense:
Current	5,052	5,818	5,176
Deferred	7,388	15,086	(5,497)
Total income taxes	$ 12,440	$ 20,904	$ (321)

Income taxes - Income tax exp_2

Income taxes - Income tax expense reconciliation (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income tax expense reconciliation
Earnings before income taxes	$ 55,693	$ 102,696	$ 4,001
Hypothetical income tax expense computed at the U.S. federal statutory rate	11,696	21,566	840
Dividends received deduction and tax-exempt interest	(448)	(433)	(393)
State income taxes, less U.S. federal income tax benefit	858	494	138
Foreign tax rate differences	13	(6)	271
U.S. income tax credits	(1,519)	(942)	(711)
Net benefit from the enactment of the TCJA			(302)
Goodwill impairments	1,977	20	21
Other differences, net	(137)	205	(185)
Total income taxes	$ 12,440	$ 20,904	$ (321)
Effective income tax rate	22.30%	20.40%	(8.00%)

Dividend restrictions - Insur_2

Dividend restrictions - Insurance subsidiaries (Detail) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
Statutory Accounting Practices [Line Items]
Investments in fixed maturity and equity securities and short-term investments on deposit with U.S. state insurance authorities	$ 5.5	$ 6.3
Principal Insurance Subsidiaries [Member]
Statutory Accounting Practices [Line Items]
Amount available for payment of dividends without prior regulatory approval during 2021	23
United States Based Property and Casualty Insurance Subsidiaries [Member]
Statutory Accounting Practices [Line Items]
Statutory shareholders' equity	$ 237	$ 216

Fair value measurements - Finan

Fair value measurements - Financial assets and liabilities (Detail) € in Millions, £ in Millions, $ in Millions, ¥ in Billions		Dec. 31, 2020USD ($)		Dec. 31, 2020EUR (€)	Dec. 31, 2020JPY (¥)	Dec. 31, 2020GBP (£)	Dec. 31, 2019USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		$ 20,410					$ 18,685
Investments in equity securities		281,170	[1]				248,027	[2]
Notes payable and other borrowings - carrying value				€ 6,850	¥ 625.5	£ 1,750
Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings - carrying value		75,373					65,778
Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		20,410					18,685
Investments in equity securities		281,170					248,027
Equity method investments - carrying value		17,303					17,505
Derivative contract liabilities		1,065					968
Notes payable and other borrowings - carrying value		41,522					37,590
The Kraft Heinz Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments - carrying value		13,300					13,800
Equity method investments		11,300					10,500
U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		3,403					3,090
Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		11,338					8,638
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		5,191					6,352
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		478					605
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		271,848					237,271
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | The Kraft Heinz Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments		11,280					10,456
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		3,358					3,046
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		9,259					5,437
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract assets	[3]	1
Fair Value, Measurements, Recurring [Member] | Quoted Prices (Level 1) [Member] | Accounts Payable, Accruals and Other Liabilities [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities	[3]	6					6
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		38					46
Loans and finance receivables		2,692					1,809
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		92,593					76,237
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		46,665					40,569
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		45					44
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		2,079					3,201
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		5,191					6,350
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		478					605
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract assets	[3]	72					23
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Accounts Payable, Accruals and Other Liabilities [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities	[3]	96					59
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		9,284					10,710
Loans and finance receivables		17,862					16,052
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		11					20
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity Index Put Options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities		1,065					968
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities							2
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract assets	[3]	197					122
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Accounts Payable, Accruals and Other Liabilities [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities	[3]	19					11
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		281,170					248,027
Loans and finance receivables		19,201					17,527
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		75,373					65,778
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		41,522					37,590
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Equity Index Put Options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities		1,065					968
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | The Kraft Heinz Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments		13,336					13,757
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		3,403					3,090
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		11,338					8,638
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		5,191					6,352
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		478					605
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract assets	[3]	270					145
Fair Value, Measurements, Recurring [Member] | Carrying Value [Member] | Accounts Payable, Accruals and Other Liabilities [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities	[3]	121					76
Fair Value, Measurements, Recurring [Member] | Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in equity securities		281,170					248,027
Loans and finance receivables		20,554					17,861
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		92,593					76,237
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Insurance and Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notes payable and other borrowings		46,676					40,589
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Equity Index Put Options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities		1,065					968
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | The Kraft Heinz Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments		11,280					10,456
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | U.S. Treasury, U.S. government corporations and agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		3,403					3,090
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Foreign governments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		11,338					8,638
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		5,191					6,352
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in fixed maturity securities		478					605
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Other Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract assets	[3]	270					145
Fair Value, Measurements, Recurring [Member] | Fair Value [Member] | Accounts Payable, Accruals and Other Liabilities [Member] | Railroad, Utilities and Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contract liabilities	[3]	$ 121					$ 76
[1]	Approximately 68% of the aggregate fair value was concentrated in four companies (American Express Company – $18.3 billion; Apple Inc. – $120.4 billion; Bank of America Corporation – $31.3 billion and The Coca-Cola Company – $21.9 billion).
[2]	Approximately 60% of the aggregate fair value was concentrated in four companies (American Express Company – $18.9 billion; Apple Inc. – $73.7 billion; Bank of America Corporation – $33.4 billion and The Coca-Cola Company – $22.1 billion).
[3]	Assets are included in other assets and liabilities are included in accounts payable, accruals and other liabilities.

Fair value measurements - Signi

Fair value measurements - Significant unobservable inputs (Detail) - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net derivative contract liabilities - Beginning Balance	$ (857)	$ (2,343)	$ (2,069)
Net derivative contract liabilities - Gains (losses) included in earnings	603	1,972	(118)
Net derivative contract liabilities - Gains (losses) included in other comprehensive income		(1)	2
Net derivative contract liabilities - Gains (losses) included in regulatory assets and liabilities	(17)	(26)	3
Net derivative contract liabilities - Acquisitions	5	6	3
Net derivative contract liabilities - Dispositions and settlements	(621)	(465)	(164)
Net derivative contract liabilities - Ending Balance	(887)	(857)	(2,343)
Investments in Equity and Fixed Maturity Securities [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	10,407	7	6
Gains (losses) included in earnings	(1,426)	404
Acquisitions		10,000	2
Dispositions and settlements	(2)	(4)	(1)
Ending Balance	$ 8,979	$ 10,407	$ 7

Fair value measurements - Narra

Fair value measurements - Narrative (Detail) - Occidental Corporation [Member] - USD ($) $ in Billions	1 Months Ended	12 Months Ended
	Aug. 31, 2019	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Acquisition of preferred and common stock warrants	$ 10
Preferred Stock [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments in equity securities, description		The Occidental Preferred is redeemable at Occidental’s option beginning in 2029.
Common Stock Warrants [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investments in equity securities, description		The Occidental common stock warrants contractually expire on the one-year anniversary on which no Occidental Preferred remains outstanding.

Fair value measurements - Other

Fair value measurements - Other information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)		Dec. 31, 2019USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of investments	$ 281,170	[1]	$ 248,027	[2]
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of investments	9,284		$ 10,710
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Option Pricing Model [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative contract liabilities, fair value	1,065
Significant Unobservable Inputs (Level 3) [Member] | Preferred Stock [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of investments	8,891
Significant Unobservable Inputs (Level 3) [Member] | Common Stock Warrants [Member] | Fair Value, Measurements, Recurring [Member] | Warrant Pricing Model [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of investments	$ 86
Significant Unobservable Inputs (Level 3) [Member] | Expected Duration [Member] | Preferred Stock [Member] | Weighted Average [Member] | Fair Value, Measurements, Recurring [Member] | Discounted Cash Flow [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, term	9 years
Significant Unobservable Inputs (Level 3) [Member] | Expected Duration [Member] | Common Stock Warrants [Member] | Weighted Average [Member] | Fair Value, Measurements, Recurring [Member] | Warrant Pricing Model [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs, term	9 years
Significant Unobservable Inputs (Level 3) [Member] | Discount for Transferability Restrictions and Subordination [Member] | Preferred Stock [Member] | Weighted Average [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs	0.0375
Significant Unobservable Inputs (Level 3) [Member] | Volatility [Member] | Weighted Average [Member] | Fair Value, Measurements, Recurring [Member] | Option Pricing Model [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs	0.19
Significant Unobservable Inputs (Level 3) [Member] | Volatility [Member] | Common Stock Warrants [Member] | Weighted Average [Member] | Fair Value, Measurements, Recurring [Member] | Warrant Pricing Model [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Unobservable inputs	0.32
[1]	Approximately 68% of the aggregate fair value was concentrated in four companies (American Express Company – $18.3 billion; Apple Inc. – $120.4 billion; Bank of America Corporation – $31.3 billion and The Coca-Cola Company – $21.9 billion).
[2]	Approximately 60% of the aggregate fair value was concentrated in four companies (American Express Company – $18.9 billion; Apple Inc. – $73.7 billion; Bank of America Corporation – $33.4 billion and The Coca-Cola Company – $22.1 billion).

Accumulated other comprehensi_3

Accumulated other comprehensive income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 424,791
Other comprehensive income, net	1,000	$ (228)	$ (2,211)
Ending Balance	443,164	424,791
Cumulative effect, period of adoption, adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(61,375)
Unrealized appreciation of investments, net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	481	370	62,093
Other comprehensive income, net	55	111	(383)
Ending Balance	536	481	370
Unrealized appreciation of investments, net [Member] | Cumulative effect, period of adoption, adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(61,340)
Foreign currency translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(4,346)	(4,603)	(3,114)
Other comprehensive income, net	1,264	257	(1,424)
Ending Balance	(3,082)	(4,346)	(4,603)
Foreign currency translation [Member] | Cumulative effect, period of adoption, adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(65)
Defined benefit pension plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,369)	(816)	(420)
Other comprehensive income, net	(276)	(553)	(432)
Ending Balance	(1,645)	(1,369)	(816)
Defined benefit pension plans [Member] | Cumulative effect, period of adoption, adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			36
Other AOCI transactions [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9)	34	12
Other comprehensive income, net	(43)	(43)	28
Ending Balance	(52)	(9)	34
Other AOCI transactions [Member] | Cumulative effect, period of adoption, adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(6)
Accumulated other comprehensive income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5,243)	(5,015)	58,571
Ending Balance	$ (4,243)	$ (5,243)	$ (5,015)

Common stock - Narrative (Detai

Common stock - Narrative (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)Voteshares	Dec. 31, 2019shares	Dec. 31, 2018shares	Dec. 31, 2017shares
Class of Stock [Line Items]
Preferred Stock, shares authorized	1,000,000
Preferred Stock, shares issued	0
Economic equivalent of Class B share to Class A share	0.0667%
Common Stock Repurchase Program [Member]
Class of Stock [Line Items]
Shares repurchase, authorization description	Berkshire’s common stock repurchase program, as amended, permits Berkshire to repurchase shares any time that Warren Buffett, Berkshire’s Chairman of the Board and Chief Executive Officer, and Charlie Munger, Vice Chairman of the Board, believe that the repurchase price is below Berkshire’s intrinsic value, conservatively determined.
Minimum cash, cash equivalents and U.S. Treasury Bill threshold after repurchase of common stock shares, amount | $	$ 20,000,000,000
Class A [Member]
Class of Stock [Line Items]
Number of votes entitled per share, number | Vote	1
Shares outstanding	643,931	701,970	729,316	751,075
Class B [Member]
Class of Stock [Line Items]
Number of votes entitled per share, number | Vote	0.0001
Number of shares of Class B stock obtainable from converting one Class A share	1,500
Shares outstanding	1,350,043,471	1,384,481,533	1,367,420,074	1,340,656,987
Equivalent Class A [Member]
Class of Stock [Line Items]
Shares outstanding	1,543,960	1,624,958

Common stock (Detail)

Common stock (Detail) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class A [Member]
Class of Stock [Line Items]
Shares issued, beginning balance	719,307	742,213	762,755
Treasury shares, beginning balance	(17,337)	(12,897)	(11,680)
Shares outstanding, beginning balance	701,970	729,316	751,075
Conversions of Class A common stock to Class B common stock and exercises of replacement stock options	(40,784)	(22,906)	(20,542)
Treasury stock acquired	(17,255)	(4,440)	(1,217)
Shares issued, ending balance	678,523	719,307	742,213
Treasury shares, ending balance	(34,592)	(17,337)	(12,897)
Shares outstanding, ending balance	643,931	701,970	729,316
Class B [Member]
Class of Stock [Line Items]
Shares issued, beginning balance	1,408,183,852	1,373,558,983	1,342,066,749
Treasury shares, beginning balance	(23,702,319)	(6,138,909)	(1,409,762)
Shares outstanding, beginning balance	1,384,481,533	1,367,420,074	1,340,656,987
Conversions of Class A common stock to Class B common stock and exercises of replacement stock options	61,176,000	34,624,869	31,492,234
Treasury stock acquired	(95,614,062)	(17,563,410)	(4,729,147)
Shares issued, ending balance	1,469,359,852	1,408,183,852	1,373,558,983
Treasury shares, ending balance	(119,316,381)	(23,702,319)	(6,138,909)
Shares outstanding, ending balance	1,350,043,471	1,384,481,533	1,367,420,074

Common stock (Parenthetical) (D

Common stock (Parenthetical) (Detail)	Dec. 31, 2020$ / sharesshares
Class A [Member]
Class of Stock [Line Items]
Common Stock, par value per share | $ / shares	$ 5
Common Stock, shares authorized | shares	1,650,000
Class B [Member]
Class of Stock [Line Items]
Common Stock, par value per share | $ / shares	$ 0.0033
Common Stock, shares authorized | shares	3,225,000,000

Revenue from contracts with cus

Revenue from contracts with customers disaggregated by reportable segment and source of revenue (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									$ 166,733	$ 176,512	$ 175,445
Other revenues									78,777	78,104	72,392
Total revenues	$ 64,381	$ 63,024	$ 56,840	$ 61,265	$ 65,368	$ 64,972	$ 63,598	$ 60,678	245,510	254,616	247,837
Industrial and Commercial Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,964	25,495	25,911
Building Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,943	15,620	14,323
Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									14,757	14,120	14,790
Grocery and Convenience Store Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									30,795	33,057	33,518
Food and Beverage Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,368	16,767	16,309
Auto Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									8,258	8,481	8,181
Other Retail and Wholesale Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									14,922	14,512	14,158
Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									30,660	33,641	33,304
Electricity and Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,066	14,819	14,951
Manufacturing Businesses [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									55,380	58,992	58,430
Other revenues									3,598	3,632	3,340
Total revenues									58,978	62,624	61,770
Manufacturing Businesses [Member] | Industrial and Commercial Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,772	25,311	25,707
Manufacturing Businesses [Member] | Building Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,943	15,620	14,323
Manufacturing Businesses [Member] | Consumer Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									14,757	14,120	14,790
Manufacturing Businesses [Member] | Other Retail and Wholesale Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									2,452	2,299	2,091
Manufacturing Businesses [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									1,456	1,642	1,519
McLane Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									46,747	50,363	49,911
Other revenues									93	95	76
Total revenues									46,840	50,458	49,987
McLane Company [Member] | Grocery and Convenience Store Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									30,795	33,057	33,518
McLane Company [Member] | Food and Beverage Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,368	16,767	16,309
McLane Company [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									584	539	84
Service and Retailing Businesses [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									24,252	24,940	24,552
Other revenues									3,859	4,459	4,297
Total revenues									28,111	29,399	28,849
Service and Retailing Businesses [Member] | Industrial and Commercial Products [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									192	184	204
Service and Retailing Businesses [Member] | Auto Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									8,258	8,481	8,181
Service and Retailing Businesses [Member] | Other Retail and Wholesale Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									12,470	12,213	12,067
Service and Retailing Businesses [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									3,332	4,062	4,100
BNSF [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,693	23,302	23,652
Other revenues									57	55	51
Total revenues									20,750	23,357	23,703
BNSF [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									20,693	23,302	23,652
Berkshire Hathaway Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									19,661	18,915	18,900
Other revenues									1,353	1,181	1,070
Total revenues									21,014	20,096	19,970
Berkshire Hathaway Energy [Member] | Service [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									4,595	4,096	3,949
Berkshire Hathaway Energy [Member] | Electricity and Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers									15,066	14,819	14,951
Insurance Corporate And Other [Member]
Disaggregation of Revenue [Line Items]
Other revenues									69,817	68,682	63,558
Total revenues									$ 69,817	$ 68,682	$ 63,558

Revenue from contracts with c_2

Revenue from contracts with customers transaction price allocated to remaining performance obligations and timing of when performance obligations expected to be satisfied (Detail) $ in Millions	Dec. 31, 2020USD ($)
Electricity and Natural Gas [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 25,298
Electricity and Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 3,210
Performance obligations expected to be satisfied, period	1 year
Electricity and Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 22,088
Performance obligations expected to be satisfied, period
Other Sales and Service Contracts [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 3,610
Other Sales and Service Contracts [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 1,228
Performance obligations expected to be satisfied, period	1 year
Other Sales and Service Contracts [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 2,382
Performance obligations expected to be satisfied, period

Revenue from contracts with c_3

Revenue from contracts with customers transaction price allocated to remaining performance obligations and timing of when performance obligations expected to be satisfied (Detail 1) $ in Millions	Dec. 31, 2020USD ($)
Electricity and Natural Gas [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 25,298
Other Sales and Service Contracts [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to remaining performance obligations	$ 3,610

Pension plans - Net periodic pe

Pension plans - Net periodic pension expense (Detail) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components of net periodic pension expense
Service cost	$ 235	$ 224	$ 271
Interest cost	510	618	593
Expected return on plan assets	(955)	(936)	(988)
Amortization of actuarial losses and other	171	26	188
Net periodic pension expense	$ (39)	$ (68)	$ 64

Pension plans - Defined benefit

Pension plans - Defined benefit pension plans - Narrative (Detail) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 20,429	$ 18,706	$ 16,922
Amounts recognized in the Consolidated Balance Sheets:
Funded status reflected in assets	1,351	857
Funded status reflected in liabilities	3,842	3,067
ABO	19,400	17,500
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2021	1,105
2022	1,031
2023	1,034
2024	1,037
2025	1,040
2026 - 2030	5,119
Expected contribution to pension plans during the next year	202
Unfunded Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 1,600	$ 1,300

Pension plans - Projected benef

Pension plans - Projected benefit obligation, plan assets and net funded status (Detail) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Benefit obligations
PBO beginning of year	$ 18,706	$ 16,922
Service cost	235	224	$ 271
Interest cost	510	618	593
Benefits paid	(994)	(1,033)
Settlements	(75)	(167)
Actuarial (gains) or losses and other	2,047	2,142
PBO end of year	20,429	18,706	16,922
Plan assets
Plan assets beginning of year	16,496	14,959
Employer contributions	196	199
Benefits paid	(994)	(1,033)
Actual return on plan assets	2,374	2,414
Settlements	(75)	(167)
Other	(59)	124
Plan assets end of year	17,938	16,496	14,959
Funded status – net liability	2,491	2,210
Berkshire Hathaway Energy [Member]
Benefit obligations
PBO beginning of year	4,898	4,551
Service cost	33	32
Interest cost	133	161
Benefits paid	(285)	(257)
Settlements	(63)	(121)
Actuarial (gains) or losses and other	566	532
PBO end of year	5,282	4,898	4,551
Plan assets
Plan assets beginning of year	4,808	4,385
Employer contributions	69	68
Benefits paid	(285)	(257)
Actual return on plan assets	554	650
Settlements	(63)	(121)
Other	75	83
Plan assets end of year	5,158	4,808	4,385
Funded status – net liability	124	90
Other [Member]
Benefit obligations
PBO beginning of year	13,808	12,371
Service cost	202	192
Interest cost	377	457
Benefits paid	(709)	(776)
Settlements	(12)	(46)
Actuarial (gains) or losses and other	1,481	1,610
PBO end of year	15,147	13,808	12,371
Plan assets
Plan assets beginning of year	11,688	10,574
Employer contributions	127	131
Benefits paid	(709)	(776)
Actual return on plan assets	1,820	1,764
Settlements	(12)	(46)
Other	(134)	41
Plan assets end of year	12,780	11,688	$ 10,574
Funded status – net liability	$ 2,367	$ 2,120

Pension plans - Schedule of inf

Pension plans - Schedule of information for plans with PBOs and ABOs in excess of plan assets (Detail) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
PBOs	$ 12,775	$ 12,625
Plan assets	9,018	9,627
ABOs	10,875	10,617
Plan assets	$ 7,820	$ 8,367

Pension plans - Additional tabu

Pension plans - Additional tabular disclosures (Detail) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Discount rate applicable to pension benefit obligations	2.30%	3.10%	3.90%
Expected long-term rate of return on plan assets	6.20%	6.40%	6.40%
Rate of compensation increase	2.60%	2.50%	2.60%
Discount rate applicable to net periodic pension expense	3.10%	4.00%	3.40%
Amounts recognized in other comprehensive income:
Accumulated other comprehensive income (loss), beginning of year	$ (1,896)	$ (1,184)
Amount included in net periodic pension expense	141	94
Actuarial gains (losses) and other	(496)	(806)
Accumulated other comprehensive income (loss), end of year	$ (2,251)	$ (1,896)	$ (1,184)

Pension plans - Fair value of p

Pension plans - Fair value of plan assets (Detail) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 17,938	$ 16,496	$ 14,959
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	383	412
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,383	11,105
Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,173	2,328
Investment Funds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,999	2,651
Quoted Prices (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	12,778	11,905
Quoted Prices (Level 1) [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	243	309
Quoted Prices (Level 1) [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10,123	9,860
Quoted Prices (Level 1) [Member] | Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,214	1,593
Quoted Prices (Level 1) [Member] | Investment Funds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	198	143
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,315	2,001
Significant Other Observable Inputs (Level 2) [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	140	103
Significant Other Observable Inputs (Level 2) [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	851	836
Significant Other Observable Inputs (Level 2) [Member] | Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	926	704
Significant Other Observable Inputs (Level 2) [Member] | Investment Funds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	398	358
Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	498	480
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	409	409
Significant Unobservable Inputs (Level 3) [Member] | Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	33	31
Significant Unobservable Inputs (Level 3) [Member] | Investment Funds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	56	40
Investment Funds and Partnerships at Net Asset Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,347	2,110
Investment Funds and Partnerships at Net Asset Value [Member] | Investment Funds and Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 2,347	$ 2,110

Pension plans - Defined contrib

Pension plans - Defined contribution pension plans - Narrative (Detail) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan [Abstract]
Contributions to defined contribution plans	$ 1.4	$ 1.2	$ 1

Contingencies and Commitments -

Contingencies and Commitments - Narrative (Detail) $ in Billions	Dec. 31, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
Purchase commitments - 2021	$ 14.6
Purchase commitments - 2022	4.5
Purchase commitments - 2023	3.4
Purchase commitments - 2024	2.8
Purchase commitments - 2025	3.1
Purchase commitments - After 2025	20
Estimated cost to acquire certain equity ownership interests of less than wholly-owned subsidiaries	$ 6.3

Supplemental cash flow inform_3

Supplemental cash flow information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for income taxes	$ 5,001	$ 5,415	$ 4,354
Non-cash investing and financing activities:
Liabilities assumed in connection with business acquisitions	6,981	766	3,735
Operating lease liabilities arising from obtaining right-of-use assets	729	782
Insurance and Other [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	1,001	1,011	1,111
Railroad, Utilities and Energy [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	$ 3,006	$ 2,879	$ 2,867

Business segment data - Revenue

Business segment data - Revenues (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 64,381	$ 63,024	$ 56,840	$ 61,265	$ 65,368	$ 64,972	$ 63,598	$ 60,678	$ 245,510	$ 254,616	$ 247,837
BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues									20,750	23,357	23,703
Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues									21,014	20,096	19,970
Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues									58,978	62,624	61,770
McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues									46,840	50,458	49,987
Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues									28,111	29,399	28,849
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues									245,358	253,997	247,587
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Premiums earned									63,401	61,078	57,418
Interest, dividend and other investment income									5,960	6,615	5,518
Total revenues									69,361	67,693	62,936
Operating Businesses [Member] | Insurance Group [Member] | GEICO [Member]
Segment Reporting Information [Line Items]
Premiums earned									35,093	35,572	33,363
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member]
Segment Reporting Information [Line Items]
Premiums earned									18,693	16,341	15,944
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Primary Group [Member]
Segment Reporting Information [Line Items]
Premiums earned									9,615	9,165	8,111
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Total revenues									20,869	23,515	23,855
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Total revenues									21,031	20,114	19,987
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues									59,079	62,730	61,883
Operating Businesses [Member] | McLane Company [Member]
Segment Reporting Information [Line Items]
Total revenues									46,840	50,458	49,987
Operating Businesses [Member] | Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Total revenues									28,178	29,487	28,939
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Total revenues									$ 152	$ 619	$ 250

Business segment data - Earning

Business segment data - Earnings (loss) before income taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Investment and derivative gains/losses	$ 40,746	$ 72,607	$ (22,455)
Interest expense	(4,083)	(3,961)	(3,853)
Equity method investments	726	1,176	(2,167)
Earnings (loss) before income taxes	55,693	102,696	4,001
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	26,947	29,250	29,156
Interest expense	(3,776)	(3,743)	(3,614)
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	6,787	7,017	7,513
Operating Businesses [Member] | Insurance Group [Member] | Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	838	417	2,010
Operating Businesses [Member] | Insurance Group [Member] | Interest, Dividend and Other Investment Income [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	5,949	6,600	5,503
Operating Businesses [Member] | Insurance Group [Member] | GEICO [Member] | Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	3,428	1,506	2,449
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Reinsurance Group [Member] | Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	(2,700)	(1,472)	(1,109)
Operating Businesses [Member] | Insurance Group [Member] | Berkshire Hathaway Primary Group [Member] | Insurance Premiums Earned [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	110	383	670
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	6,792	7,250	6,863
Interest expense	(1,037)	(1,070)	(1,041)
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	2,479	2,618	2,472
Interest expense	(1,941)	(1,835)	(1,777)
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	8,010	9,522	9,366
Interest expense	(737)	(752)	(690)
Operating Businesses [Member] | McLane Company [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	251	288	246
Interest expense			(15)
Operating Businesses [Member] | Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	2,628	2,555	2,696
Interest expense	(61)	(86)	(91)
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Investment and derivative gains/losses	40,746	72,607	(22,455)
Interest expense	(483)	(416)	(458)
Equity method investments	726	1,176	(2,167)
Goodwill and intangible asset impairments	(10,671)	(96)	(382)
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Earnings (loss) before income taxes from operating businesses	(1,572)	175	307
Interest expense	$ 176	$ 198	$ 219

Business segment data - Additio

Business segment data - Additional tabular disclosures (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Segment Reporting Information [Line Items]
Interest expense	$ 4,083		$ 3,961		$ 3,853
Income tax expense	12,440		20,904		(321)
Capital expenditures	13,012		15,979		14,537
Depreciation of tangible assets	8,119		7,566		7,284
Goodwill at year-end	73,734	[1]	81,882	[1]	81,025
Assets	873,729		817,729		707,794
Operating Businesses [Member]
Segment Reporting Information [Line Items]
Interest expense	3,776		3,743		3,614
Income tax expense	4,245		5,336		5,447
Capital expenditures	13,012		15,979		14,537
Depreciation of tangible assets	9,319		8,747		8,386
Goodwill at year-end	73,734		81,882		81,025
Identifiable assets at year-end	719,526		664,703		571,410
Operating Businesses [Member] | Insurance Group [Member]
Segment Reporting Information [Line Items]
Income tax expense	1,089		1,166		1,374
Capital expenditures	50		108		130
Depreciation of tangible assets	74		82		79
Goodwill at year-end	15,224		15,289		15,289
Identifiable assets at year-end	399,169		364,550		289,746
Operating Businesses [Member] | BNSF [Member]
Segment Reporting Information [Line Items]
Interest expense	1,037		1,070		1,041
Income tax expense	1,631		1,769		1,644
Capital expenditures	3,063		3,608		3,187
Depreciation of tangible assets	2,423		2,350		2,268
Goodwill at year-end	14,851		14,851		14,851
Identifiable assets at year-end	73,809		73,699		70,242
Operating Businesses [Member] | Berkshire Hathaway Energy [Member]
Segment Reporting Information [Line Items]
Interest expense	1,941		1,835		1,777
Income tax expense	(1,010)		(526)		(452)
Capital expenditures	6,765		7,364		6,241
Depreciation of tangible assets	3,376		2,947		2,830
Goodwill at year-end	11,763		9,979		9,851
Identifiable assets at year-end	109,286		88,651		80,543
Operating Businesses [Member] | Manufacturing Businesses [Member]
Segment Reporting Information [Line Items]
Interest expense	737		752		690
Income tax expense	1,795		2,253		2,188
Capital expenditures	2,133		2,981		3,116
Depreciation of tangible assets	2,026		1,951		1,890
Goodwill at year-end	25,512		34,800		34,019
Identifiable assets at year-end	104,318		104,437		99,912
Operating Businesses [Member] | McLane Company [Member]
Segment Reporting Information [Line Items]
Interest expense					15
Income tax expense	71		71		59
Capital expenditures	98		158		276
Depreciation of tangible assets	204		225		204
Goodwill at year-end	232		734		734
Identifiable assets at year-end	6,771		6,872		6,243
Operating Businesses [Member] | Service and Retailing Businesses [Member]
Segment Reporting Information [Line Items]
Interest expense	61		86		91
Income tax expense	669		603		634
Capital expenditures	903		1,760		1,587
Depreciation of tangible assets	1,216		1,192		1,115
Goodwill at year-end	6,152		6,229		6,281
Identifiable assets at year-end	26,173		26,494		24,724
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Interest expense	483		416		458
Investment and derivative gains/losses, tax	8,855		15,159		(4,673)
Interest expense, not allocated to segments, tax	(102)		(88)		(96)
Equity method investments, tax	57		148		(753)
Goodwill at year-end	73,734		81,882		81,025
Corporate, Eliminations and Other [Member]
Segment Reporting Information [Line Items]
Interest expense	(176)		(198)		(219)
Income tax expense	(615)		349		(246)
Identifiable assets at year-end	$ 80,469		$ 71,144		$ 55,359
[1]	Net of accumulated goodwill impairments of $11.0 billion as of December 31, 2020 and $1.1 billion as of December 31, 2019.

Business segment data - Insuran

Business segment data - Insurance premiums by type (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property/Casualty [Member]
Segment Reporting Information [Line Items]
Premiums written - Direct	$ 47,838	$ 47,578	$ 44,513
Premiums written - Assumed	11,533	10,214	8,970
Premiums written - Ceded	(898)	(821)	(869)
Premiums written	58,473	56,971	52,614
Premiums earned - Direct	46,418	46,540	43,095
Premiums earned - Assumed	11,449	9,643	8,649
Premiums earned - Ceded	(907)	(851)	(825)
Premiums earned	56,960	55,332	50,919
Life/Health [Member]
Segment Reporting Information [Line Items]
Premiums written - Direct	510	839	1,111
Premiums written - Assumed	5,960	5,046	5,540
Premiums written - Ceded	(42)	(45)	(49)
Premiums written	6,428	5,840	6,602
Premiums earned - Direct	510	839	1,111
Premiums earned - Assumed	5,973	4,952	5,438
Premiums earned - Ceded	(42)	(45)	(50)
Premiums earned	$ 6,441	$ 5,746	$ 6,499

Business segment data - Insur_2

Business segment data - Insurance premiums by geographic area (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property/Casualty [Member]
Segment Reporting Information [Line Items]
Premiums written	$ 58,473	$ 56,971	$ 52,614
Life/Health [Member]
Segment Reporting Information [Line Items]
Premiums written	6,428	5,840	6,602
United States [Member] | Property/Casualty [Member]
Segment Reporting Information [Line Items]
Premiums written	50,250	50,529	46,146
United States [Member] | Life/Health [Member]
Segment Reporting Information [Line Items]
Premiums written	2,820	2,553	3,598
Asia Pacific [Member] | Property/Casualty [Member]
Segment Reporting Information [Line Items]
Premiums written	3,410	3,114	3,726
Asia Pacific [Member] | Life/Health [Member]
Segment Reporting Information [Line Items]
Premiums written	1,652	1,582	1,361
Western Europe [Member] | Property/Casualty [Member]
Segment Reporting Information [Line Items]
Premiums written	3,751	2,535	2,157
Western Europe [Member] | Life/Health [Member]
Segment Reporting Information [Line Items]
Premiums written	1,120	908	939
All Other [Member] | Property/Casualty [Member]
Segment Reporting Information [Line Items]
Premiums written	1,062	793	585
All Other [Member] | Life/Health [Member]
Segment Reporting Information [Line Items]
Premiums written	$ 836	$ 797	$ 704

Business segment data - Narrati

Business segment data - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 64,381	$ 63,024	$ 56,840	$ 61,265	$ 65,368	$ 64,972	$ 63,598	$ 60,678	$ 245,510	$ 254,616	$ 247,837
Sales, Service and Leasing Revenues [Member]
Segment Reporting Information [Line Items]
Revenues									$ 132,300	$ 140,800	$ 139,100
United States [Member] | Geographic Concentration [Member] | Sales, Service and Leasing Revenues [Member]
Segment Reporting Information [Line Items]
Concentration percentage									86.00%	85.00%	84.00%
United States [Member] | Geographic Concentration [Member] | Property, Plant and Equipment and Equipment Held for Lease [Member]
Segment Reporting Information [Line Items]
Concentration percentage									89.00%
Railroad, Utilities and Energy [Member]
Segment Reporting Information [Line Items]
Revenues									$ 41,764	$ 43,453	$ 43,673
Railroad, Utilities and Energy [Member] | United States [Member] | Geographic Concentration [Member] | Revenues [Member]
Segment Reporting Information [Line Items]
Concentration percentage									96.00%	96.00%	96.00%

Quarterly data (Detail)

Quarterly data (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information [Line Items]
Revenues	$ 64,381		$ 63,024		$ 56,840		$ 61,265		$ 65,368		$ 64,972		$ 63,598		$ 60,678		$ 245,510	$ 254,616	$ 247,837
Net earnings (loss) attributable to Berkshire shareholders	35,835	[1]	30,137	[1]	26,295	[1]	(49,746)	[1]	29,159	[1]	16,524	[1]	14,073	[1]	21,661	[1]	$ 42,521	$ 81,417	$ 4,021
After-tax investment and derivative gains/losses	$ 30,826		$ 24,737		$ 31,645		$ (55,617)		$ 24,739		$ 8,666		$ 7,934		$ 16,106
Equivalent Class A [Member]
Quarterly Financial Information [Line Items]
Net earnings (loss) attributable to Berkshire shareholders per equivalent Class A common share	$ 23,015		$ 18,994		$ 16,314		$ (30,653)		$ 17,909		$ 10,119		$ 8,608		$ 13,209		$ 26,668	$ 49,828	$ 2,446
[1]	* Includes after-tax investment and derivative gains/losses as follows: 1 st Quarter 2 nd Quarter 3 rd Quarter 4 th Quarter 2020 $ (55,617 ) $ 31,645 $ 24,737 $ 30,826 2019 16,106 7,934 8,666 24,739

Condensed Financial Informati_2

Condensed Financial Information - Balance Sheets (Detail) € in Millions, £ in Millions, $ in Millions, ¥ in Billions	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2020JPY (¥)	Dec. 31, 2020GBP (£)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Assets:
Total assets	$ 873,729				$ 817,729	$ 707,794
Liabilities and Shareholders’ Equity:
Income taxes, principally deferred	74,098				66,799
Notes payable and other borrowings		€ 6,850	¥ 625.5	£ 1,750
Total liabilities	422,393				389,166
Berkshire Hathaway shareholders’ equity	443,164				424,791
Total liabilities and shareholders' equity	873,729				817,729
Berkshire Hathaway Inc. (Parent) [Member]
Assets:
Cash and cash equivalents	12,329				15,004	$ 3,437	$ 4,039
Short-term investments in U.S. Treasury Bills	29,773				25,514
Investments in and advances to/from consolidated subsidiaries	411,826				392,162
Investment in The Kraft Heinz Company	13,336				13,757
Other assets	108				131
Total assets	467,372				446,568
Liabilities and Shareholders’ Equity:
Accounts payable, accrued interest and other liabilities	369				320
Income taxes, principally deferred	1,174				1,554
Notes payable and other borrowings	22,665				19,903
Total liabilities	24,208				21,777
Berkshire Hathaway shareholders’ equity	443,164				424,791
Total liabilities and shareholders' equity	$ 467,372				$ 446,568

Condensed Financial Informati_3

Condensed Financial Information - Statements of Earnings and Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
From consolidated subsidiaries:
Investment gains (losses)																	$ 40,905	$ 71,123	$ (22,155)
Equity method earnings (losses)																	726	1,176	(2,167)
Total revenues	$ 64,381		$ 63,024		$ 56,840		$ 61,265		$ 65,368		$ 64,972		$ 63,598		$ 60,678		245,510	254,616	247,837
Cost and expense items:
Interest expense																	4,083	3,961	3,853
Income tax expense (benefit)																	12,440	20,904	(321)
Total costs and expenses																	231,289	225,703	219,214
Net earnings attributable to Berkshire Hathaway shareholders	$ 35,835	[1]	$ 30,137	[1]	$ 26,295	[1]	$ (49,746)	[1]	$ 29,159	[1]	$ 16,524	[1]	$ 14,073	[1]	$ 21,661	[1]	42,521	81,417	4,021
Other comprehensive income, net																	1,000	(228)	(2,211)
Comprehensive income attributable to Berkshire Hathaway shareholders																	43,521	81,189	1,810
Berkshire Hathaway Inc. (Parent) [Member]
From consolidated subsidiaries:
Dividends and distributions																	26,110	15,603	9,658
Undistributed earnings (losses)																	17,402	65,237	(3,952)
Total income from consolidated subsidiaries																	43,512	80,840	5,706
Investment gains (losses)																	(24)	(125)	(4)
Equity method earnings (losses)																	95	493	(2,730)
Other income																	328	780	649
Total revenues																	43,911	81,988	3,621
Cost and expense items:
General and administrative																	194	122	216
Interest expense																	489	591	601
Foreign exchange (gains) losses on non-U.S. Dollar denominated debt																	970	(193)	(366)
Income tax expense (benefit)																	(263)	51	(851)
Total costs and expenses																	1,390	571	(400)
Net earnings attributable to Berkshire Hathaway shareholders																	42,521	81,417	4,021
Other comprehensive income, net																	1,000	(228)	(2,211)
Comprehensive income attributable to Berkshire Hathaway shareholders																	$ 43,521	$ 81,189	$ 1,810
[1]	* Includes after-tax investment and derivative gains/losses as follows: 1 st Quarter 2 nd Quarter 3 rd Quarter 4 th Quarter 2020 $ (55,617 ) $ 31,645 $ 24,737 $ 30,826 2019 16,106 7,934 8,666 24,739

Condensed Financial Informati_4

Condensed Financial Information - Statements of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020	[1]	Jun. 30, 2020	[1]	Mar. 31, 2020		Dec. 31, 2019		Sep. 30, 2019	[1]	Jun. 30, 2019	[1]	Mar. 31, 2019		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net earnings attributable to Berkshire Hathaway shareholders	$ 35,835	[1]	$ 30,137		$ 26,295		$ (49,746)	[1]	$ 29,159	[1]	$ 16,524		$ 14,073		$ 21,661	[1]	$ 42,521	$ 81,417	$ 4,021
Adjustments to reconcile net earnings to cash flows from operating activities:
Investment gains/losses																	(40,905)	(71,123)	22,155
Income taxes payable																	7,195	15,181	(4,957)
Net cash flows from operating activities																	39,773	38,687	37,400
Cash flows from investing activities:
Other																	(3,582)	(1,496)	(71)
Net cash flows from investing activities																	(37,757)	(5,621)	(32,849)
Cash flows from financing activities:
Acquisition of treasury stock																	(24,706)	(4,850)	(1,346)
Other																	(429)	(497)	(343)
Net cash flows from financing activities																	(18,344)	730	(5,812)
Other cash flow information:
Income taxes paid																	5,001	5,415	4,354
Berkshire Hathaway Inc. (Parent) [Member]
Cash flows from operating activities:
Net earnings attributable to Berkshire Hathaway shareholders																	42,521	81,417	4,021
Adjustments to reconcile net earnings to cash flows from operating activities:
Investment gains/losses																	24	125	4
Undistributed earnings of consolidated subsidiaries																	(17,402)	(65,237)	3,952
Non-cash dividends from subsidiaries																	(8,296)
Income taxes payable																	(72)	(56)	(972)
Other																	1,100	(693)	3,062
Net cash flows from operating activities																	17,875	15,556	10,067
Cash flows from investing activities:
Investments in and advances to/from consolidated subsidiaries, net																	(1,947)	60	460
Purchases of U.S. Treasury Bills																	(54,715)	(40,107)	(29,740)
Sales and maturities of U.S. Treasury Bills																	59,035	36,943	21,442
Other																	11	737
Net cash flows from investing activities																	2,384	(2,367)	(7,838)
Cash flows from financing activities:
Proceeds from borrowings																	2,923	3,967	17
Repayments of borrowings																	(1,151)	(758)	(1,563)
Acquisition of treasury stock																	(24,706)	(4,850)	(1,346)
Other																		19	61
Net cash flows from financing activities																	(22,934)	(1,622)	(2,831)
Increase (decrease) in cash and cash equivalents																	(2,675)	11,567	(602)
Cash and cash equivalents at beginning of year							$ 15,004								$ 3,437		15,004	3,437	4,039
Cash and cash equivalents at end of year	$ 12,329								$ 15,004								12,329	15,004	3,437
Other cash flow information:
Income taxes paid																	3,391	3,531	2,790
Interest paid																	$ 359	$ 364	$ 388
[1]	* Includes after-tax investment and derivative gains/losses as follows: 1 st Quarter 2 nd Quarter 3 rd Quarter 4 th Quarter 2020 $ (55,617 ) $ 31,645 $ 24,737 $ 30,826 2019 16,106 7,934 8,666 24,739

Note to Condensed Financial Inf

Note to Condensed Financial Information - Narrative (Detail) € in Millions, $ in Millions, ¥ in Billions	1 Months Ended			12 Months Ended
	Apr. 30, 2020USD ($)	Apr. 30, 2020JPY (¥)	Mar. 31, 2020EUR (€)	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2020JPY (¥)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020EUR (€)	Dec. 31, 2020JPY (¥)
Condensed Financial Statements, Captions [Line Items]
Debt maturities: 2021				$ 9,398
Debt maturities: 2022				4,998
Debt maturities: 2023				10,813
Debt maturities: 2024				6,308
Debt maturities: 2025				6,594
Insurance and Other [Member]
Condensed Financial Statements, Captions [Line Items]
Debt maturities: 2021				4,354
Debt maturities: 2022				1,593
Debt maturities: 2023				6,021
Debt maturities: 2024				2,343
Debt maturities: 2025				2,817
Berkshire Hathaway Inc. (Parent) [Member]
Condensed Financial Statements, Captions [Line Items]
Repayments of borrowings				1,151			$ 758	$ 1,563
Principal amount of debt issued									€ 6,850	¥ 625.5
Debt maturities: 2021				2,172
Debt maturities: 2022				600
Debt maturities: 2023				4,633
Debt maturities: 2024				2,272
Debt maturities: 2025				1,801
Guarantees of subsidiary debt				14,400
Berkshire Hathaway Inc. (Parent) [Member] | Berkshire Hathaway Finance Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Guarantees of subsidiary debt				$ 13,100
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Senior Notes [Member] | Notes Due 2025 at 0.0% [Member]
Condensed Financial Statements, Captions [Line Items]
Repayments of borrowings | €			€ 1,000		€ 1,000
Principal amount of debt issued | €			€ 1,000		€ 1,000
Debt instrument, interest rate, stated percentage			0.00%	0.00%					0.00%	0.00%
Debt maturity year			2025	2025	2025	2025
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Senior Notes [Member] | Debt Due 2023 To 2060 [Member]
Condensed Financial Statements, Captions [Line Items]
Principal amount of debt issued	$ 1,800	¥ 195.5		$ 1,800		¥ 195.5
Weighted average interest rate, percentage	1.07%	1.07%		1.07%					1.07%	1.07%
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Senior Notes [Member] | Debt Due 2023 To 2060 [Member] | Minimum [Member]
Condensed Financial Statements, Captions [Line Items]
Debt maturity year	2023	2023		2023	2023	2023
Berkshire Hathaway Inc. (Parent) [Member] | Insurance and Other [Member] | Senior Notes [Member] | Debt Due 2023 To 2060 [Member] | Maximum [Member]
Condensed Financial Statements, Captions [Line Items]
Debt maturity year	2060	2060		2060	2060	2060
Berkshire Hathaway Inc. (Parent) [Member] | The Kraft Heinz Company [Member]
Condensed Financial Statements, Captions [Line Items]
Equity method investment ownership percentage after transactions				26.60%	26.60%	26.60%