Entity Tax Identification Number Entity Tax Identification Number Rollovers EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Rollover Total investments Investment, Fair Value EBP, Investment, Fair Value Maximum [Member] Maximum [Member] Legal Entity [Axis] Legal Entity [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Description of Plan [Table] EBP, Description of Plan [Table] Mutual Fund [Member] Mutual Fund [Member] Berkshire Hathaway Stock Fund [Member] Employee Benefit Plan, Berkshire Hathaway, Common Stock Fund [Member] Fund with common stock issued by Berkshire Hathaway in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). 401(k) Savings Plan for GHC Affiliates [Member] 401(k) Savings Plan for GHC Affiliates [Member] 401(k) Savings Plan for GHC Affiliates Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] EBP020 [Member] EBP020 [Member] EBP020 Total deductions EBP, Change in Net Asset Available for Benefit, Decrease Maximum borrowing amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair Value Measurements [Text Block] EBP, Investment, Fair Value and NAV [Text Block] Minimum borrowing amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Maximum percentage of employee contributions to single investment EBP, Employee Contribution, Maximum, Percentage Maximum percentage allowed to single investment of total employee contributions. Amount of account balance that may not be deferred and may be subject to potential rollover/cash out EBP, Balance Subject To Potential Rollover or Cash Out, Amount Balance of account that may not be deferred and may be subject to potential rollover/automatic cash out. Administration cost absorbed by employer [true false] EBP, Administration Cost, Absorbed by Employer [true false] Plan Interest in Master Trust [Member] EBP, Nonconsolidated, Plan Interest in Master Trust [Member] Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Investment, Name [Domain] Investment, Name [Domain] EBP, Investment, Fair Value and NAV [Abstract] EBP, Investment, Fair Value and NAV [Abstract] Assets EBP, Asset [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] Additions to net assets: EBP, Change in Net Asset Available for Benefit, Increase [Abstract] Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Transfer from plan EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan Payment of Benefits [Policy Text Block] EBP, Payment to Participant [Policy Text Block] NAV, Unfunded Commitment EBP, Fair Value, Investment, NAV, Unfunded Commitment Sales Employee Benefit Plan Investment Amount Sold Dollar amount of shares sold by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Master Trust [Line Items] EBP, Master Trust [Line Items] Interest in Master Trust EBP, Asset Held for Investment, Plan Interest in Master Trust, Current Value Amendment Flag Amendment Flag Basis of Accounting [Policy Text Block] EBP, Basis of Accounting [Policy Text Block] Schedule of Assets [Table] EBP, Schedule of Asset Held for Investment [Table] EBP, Description of Plan and Accounting Change [Abstract] EBP, Description of Plan and Accounting Change [Abstract] Receivables EBP, Receivable [Abstract] Fair Value Measurements [Table Text Block] EBP, Investment, Fair Value and NAV [Table Text Block] Kaplan Tax Deferred Savings Plan [Member] Kaplan Tax Deferred Savings Plan [Member] Kaplan Tax Deferred Savings Plan Purchases Employee Benefit Plan Investment Amount Purchased Dollar amount of shares purchased by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). External Plans [Domain] External Plans [Domain] External Plans Investments [Domain] Investments [Domain] Target Date Strategy Funds [Member] Target Date Strategy Funds [Member] Target-date strategy funds in a common collective trust. Nonemployer Common Stock [Member] EBP, Nonemployer, Common Stock [Member] Hoover Treated Wood Products, Inc. 401(k) Savings Plan [Member] Hoover Treated Wood Products, Inc. 401(k) Savings Plan [Member] Hoover Treated Wood Products, Inc. 401(k) Savings Plan EBP, Master Trust [Abstract] EBP, Master Trust [Abstract] Use of Estimates [Policy Text Block] EBP, Use of Estimate [Policy Text Block] Schedule of Assets [Text Block] EBP, Schedule of Asset Held for Investment [Text Block] Cover [Abstract] Cover [Abstract] Minimum [Member] Minimum [Member] Investment Type [Axis] Investment Type [Axis] Interest income - notes receivable EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Net transfers from other affiliated plans us-gaap-ebp_EmployeeBenefitPlanChangeInNetAssetAvailableForBenefitTransferToFromAffiliatedPlan Amount of net asset available for benefit transferred to (from) employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) from (to) affiliated plan. Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Participant EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover Net appreciation in fair value of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Interest and dividends EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment Description of Plan [Line Items] EBP, Description of Plan [Line Items] Affiliated Plans [Axis] Affiliated Plans [Axis] Information of affiliated plans. Plan Number EBP, Plan Number Fair Value Measurements [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Description of Plan [Text Block] EBP, Description of Plan [Text Block] Issuer Name [Extensible Enumeration] EBP, Investment, Issuer Name [Extensible Enumeration] Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] Schedule of Assets [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] Automatic annual increase increment, Option 3 EBP, Pre-Tax Deferral, Automatic Annual Increase Increments, Percentage, Option3 Automative incremental increase of pre-tax deferrals on an annual basis up to the limits established by the Plan. Contributions [Policy Text Block] EBP, Contribution [Policy Text Block] Master Trust and Plan Interest in Master Trust [Domain] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] Automatic annual increase increment, Option 2 EBP, Pre-Tax Deferral, Automatic Annual Increase Increments, Percentage, Option2 Automative incremental increase of pre-tax deferrals on an annual basis up to the limits established by the Plan. Minimum amount of account balance that may not be deferred and are subject to automotic rollover/cash out EBP, Balance Subject To Automotic Rollover or Cash Out, Amount, Minimum Minimum balance of account that may not be deferred and are subject to automatic rollover/automatic cash out. Employer Common Stock [Member] EBP, Employer, Common Stock [Member] Automatic annual increase increment, Option 1 EBP, Pre-Tax Deferral, Automatic Annual Increase Increments, Percentage, Option1 Automative incremental increase of pre-tax deferrals on an annual basis up to the limits established by the Plan. EBP, Schedule of Asset Held for Investment [Abstract] EBP, Schedule of Asset Held for Investment [Abstract] Accounting Policy [Table] EBP, Accounting Policy [Table] Total additions EBP, Change in Net Asset Available for Benefit, Increase Investment, Identifier [Axis] Investment, Identifier [Axis] Maximum amount of account balance that may not be deferred and are subject to automotic rollover/cash out EBP, Balance Subject To Automotic Rollover or Cash Out, Amount, Maximum Maximum balance of account that may not be deferred and are subject to automatic rollover/automatic cash out. Administrative expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Total Assets Held at End of Year EBP, Asset Held for Investment Automatic deferral rate annual incremental increase, percentage EBP, Participant Contribution, Automatic, Deferral Rate, Annual Incremental Increase, Percentage Percentage of annual incremental increase of eligible compensation contributed for participant automatically enrolled in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)). Risks and Uncertainties [Text Block] EBP, Risk and Uncertainty [Policy Text Block] Document Information [Line Items] Document Information [Line Items] Master Trust [Text Block] EBP, Master Trust [Text Block] EBP, Statement of Change in Net Asset Available for Benefit [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Abstract] Tax Status [Table] EBP, Tax Status [Table] Net increase EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Related Party and Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Total receivables EBP, Receivable Automatic deferral rate EBP, Participant Contribution, Automatic, Deferral Rate Benefits paid to participants EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Plan interest in Graham Holdings Company Master Trust EBP, Investment, Plan Interest in Master Trust, Fair Value Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Affiliated Plans [Domain] Affiliated Plans [Domain] Infromation of affiliated plans. EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Statement of Net Asset Available for Benefit [Abstract] Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Tax Status [Abstract] EBP, Tax Status [Abstract] Berkshire Hathaway [Member] Berkshire Hathaway [Member] Berkshire Hathaway Employer Common Stock Fund [Member] EBP, Employer, Common Stock Fund [Member] Document Period End Date Document Period End Date Plan Interest in Master Trust, Participation Status [Extensible Enumeration] EBP, Asset Held for Investment, Plan Interest in Master Trust, Participation Status [Extensible Enumeration] Plan interest in investment income of the Graham Holdings Company Master Trust EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Change in Plan Interest in Master Trust Participant loans EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Investment Valuation and Income Recognition [Policy Text Block] EBP, Investment [Policy Text Block] Master Trust [Table] EBP, Master Trust [Table] Contributions receivable from participants EBP, Participant Contribution, Receivable Level 1, Level 2, and Level 3 [Member] Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Party-in-Interest [true false] EBP, Asset Held for Investment, Party-in-Interest [true false] Document Type Document Type Entity Central Index Key Entity Central Index Key Participant loans interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Common Collective Trust [Member] Common Collective Trust [Member] Maximum percentage of total account balance in single investment EBP, Single Investment Balance of Total Balance, Maximum, Percentage Maximum percentage allowed of a single investment of total account balance after exchanges in. Tax Status [Line Items] EBP, Tax Status [Line Items] External Plans [Axis] External Plans [Axis] External Plans Deductions from net assets: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Notes receivable from participants EBP, Note Receivable from Participant Master Trust [Member] EBP, Nonconsolidated, Master Trust [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Summary of Accounting Policy [Text Block] EBP, Summary of Accounting Policy [Text Block] Entity Registrant Name Entity Registrant Name Investment, Name [Axis] Investment, Name [Axis] Hoover Treated Wood Products, Inc. 401(k) Retirement Plan [Member] Hoover Treated Wood Products, Inc. 401(k) Retirement Plan [Member] Hoover Treated Wood Products, Inc. 401(k) Retirement Plan Master Trust [Table Text Block] EBP, Master Trust [Table Text Block] Subsequent Events [Policy Text Block] EBP, Subsequent Event [Policy Text Block] Tax Status [Text Block] EBP, Tax Status [Text Block] Maximum percentage of account balance participant may borrow EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Document Information [Table] Document Information [Table] Transfers from affiliated plans EBP, Change in Net Asset Available for Benefit, Transfer to Plan Amount of net asset available for benefit transferred to employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) from affiliated plan. Transfers from affiliated plans Employee Benefit Plan Change In Net Asset Available For Benefit Transfer To From Plan [Abstract] Employee Benefit Plan Change In Net Asset Available For Benefit Transfer To From Plan Total investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment Master Trust and Plan Interest in Master Trust [Axis] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Target Income Strategy Fund [Member] Target Income Strategy Fund [Member] Target income strategy fund in a common collective trust. Net assets available for benefits Net asset available for benefits, beginning of year Net asset available for benefits, end of year Total net assets EBP, Net Asset Available for Benefit Entity [Domain] Entity [Domain] Number of active loans Employee Benefit Plan, Note Receivable From Participant, Number of Active Loans Number of active loans that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow. Contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Fair Value Measured at Net Asset Value Per Share [Member] Fair Value Measured at Net Asset Value Per Share [Member] Fair Value Measurements [Table] EBP, Investment, Fair Value and NAV [Table] Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items] Graham Holdings Company Master Trust [Member] Graham Holdings Company Master Trust EBP, Participant-Directed [Member]