XML 95 R79.htm IDEA: XBRL DOCUMENT
v3.20.4

Employee Retirement Plans and Post-Retirement Medical Benefits - Additional Information (Detail) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Jan. 31, 2020 | Dec. 26, 2020 USD ($) CompensationPlan | Dec. 28, 2019 USD ($) | Dec. 29, 2018 USD ($)
Pension Benefit Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Unfunded projected pension benefits |  | $ 0 | $ 2,734,000 |
Retiree Medical Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Unfunded projected pension benefits |  | $ 1,077,000 | 888,000 |
Non-Union Plans |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Number of retirement plans | CompensationPlan |  | 1 |  |
Non-Union Plans | Boston Beer 401 (k) Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Eligibility timing |  | eligible to participate in the Plan immediately upon employment |  |
Voluntary contributions of annual compensation |  | 60.00% |  |
Employer matching contribution percentage |  | 5.00% |  |
Contributions Plan |  | $ 6,400,000 | 4,000,000.0 | $ 3,500,000
Non-Union Plans | Boston Beer 401 (k) Plan | Company's match thereafter |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Employer matching contribution percentage | 3.00% |  |  |
Employer match percentage | 100.00% |  |  |
Non-Union Plans | Boston Beer 401 (k) Plan | Company's match for the first 3% of the eligible participants contribute |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Employer matching contribution percentage | 5.00% |  |  |
Employer match percentage | 50.00% |  |  |
Non-Union Plans | Dogfish Head 401 (K) Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Voluntary contributions of annual compensation |  | 60.00% |  |
Employer matching contribution percentage |  | 5.00% |  |
Contributions Plan |  |  | 300,000 |
Non-Union Plans | Dogfish Head 401 (K) Plan | Company's match thereafter |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Employer match percentage |  | 50.00% |  |
Non-Union Plans | Dogfish Head 401 (K) Plan | Company's match for the first 3% of the eligible participants contribute |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Employer match percentage |  | 100.00% |  |
Contribution percentage by the company |  | 3.00% |  |
Union Plans |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Number of retirement plans | CompensationPlan |  | 2 |  |
Union Plans | Company Sponsored Pension Plans |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Eligibility timing |  | open to all union employees who are covered by the Company’s collective bargaining agreement with Teamsters Local Union. No. 1199 (“Local Union 1199”), or persons on leave from the Company who are employed by Local Union 1199, and in either case who have completed 12 consecutive months of employment with at least 750 hours worked. |  |
Eligibility period |  | 12 months |  |
Time required for eligibility |  | 750 hours |  |
Expenses on termination of defined benefit plan |  | $ 2,000,000.0 |  |
Pension contributions |  | $ 2,900,000 | $ 300,000 | $ 300,000
Union Plans | Retiree Medical Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Eligibility period |  | 20 years |  |
Time required for eligibility |  | 5 years |  |
Benefit obligation, discount rate |  | 2.50% | 3.32% |
Benefit obligation, rate of compensation increase |  | 2.50% | 2.50% | 2.50%
Percentage paid for coverage |  | 100.00% |  |
Union Plans | Retiree Medical Plan | Minimum |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Voluntarily retirement age |  | 57 years |  |
Union Plans | Retiree Medical Plan | Local #20 member |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Time required for eligibility |  | 7 years |  |
Retiree Medical Plan, last years of employment |  | 10 years |  |
Voluntarily retirement age |  | 65 years |  |
Union Plans | Retiree Medical Plan | Local #20 member | Minimum |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Eligibility period |  | 20 years |  |
Union Plans | Samuel Adams Cincinnati Brewery 401 (k) Plan |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |
Eligibility timing |  | all union employees upon commencement of employment or, if later, attaining age 21. |  |
Voluntary contributions of annual compensation |  | 60.00% |  |

X
- Definition Defined Benefit Plan Coverage Percentage + References No definition available. + Details
Name: | sam_DefinedBenefitPlanCoveragePercentage
Namespace Prefix: | sam_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined benefit plan first eligible contributions by employer. + References No definition available. + Details
Name: | sam_DefinedBenefitPlanFirstEligibleContributionsByEmployer
Namespace Prefix: | sam_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Defined Benefit Plan Service Period Of Employees To Be Eligible To Participate In Retirement Plan + References No definition available. + Details
Name: | sam_DefinedBenefitPlanServicePeriodOfEmployeesToBeEligibleToParticipateInRetirementPlan
Namespace Prefix: | sam_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum Number of Employee Working Hours Required to be Eligible to Participate in 401(k) Plan + References No definition available. + Details
Name: | sam_MinimumNumberOfEmployeeWorkingHoursRequiredToBeEligibleToParticipateInFourZeroOneKPlan
Namespace Prefix: | sam_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Defined Benefit Pension Plans + References No definition available. + Details
Name: | sam_NumberOfDefinedBenefitPensionPlans
Namespace Prefix: | sam_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Postretirement Medical Benefits Qualifying Age + References No definition available. + Details
Name: | sam_PostretirementMedicalBenefitsQualifyingAge
Namespace Prefix: | sam_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Required Customary Employment Time for Eligibility of Employee Benefits + References No definition available. + Details
Name: | sam_RequiredCustomaryEmploymentTimeForEligibilityOfEmployeeBenefits
Namespace Prefix: | sam_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Required Employment Period for Eligibility of Employee Benefits + References No definition available. + Details
Name: | sam_RequiredEmploymentPeriodForEligibilityOfEmployeeBenefits
Namespace Prefix: | sam_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(2) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109237824&loc=d3e1703-114919 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 + Details
Name: | us-gaap_DefinedBenefitPlanFundedStatusOfPlan
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(7) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
Name: | us-gaap_DefinedBenefitPlanRecognizedNetGainLossDueToSettlements1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of defined benefit pension and other postretirement plans. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlansGeneralInformation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage employer matches of the employee's percentage contribution matched. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum percentage of employee gross pay the employee may contribute to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cost (reversal of cost) for pension benefits. Excludes other postretirement benefits. + References No definition available. + Details
Name: | us-gaap_PensionExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_TitleOfIndividualAxis=sam_NonunionEmployeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanNameAxis=sam_BostonBeerCompany401kPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=sam_GroupThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=sam_GroupFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanNameAxis=sam_DogfishHead401KPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_TitleOfIndividualAxis=sam_UnionEmployeesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=sam_CompanySponsoredPensionPlansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | sam_DefinedBenefitPlansAndOtherPostretirementBenefitPlansAdditionalInformationAxis=sam_TheInternationalUnionOfOperatingEngineersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanNameAxis=sam_SamuelAdamsCincinnatiBrewery401kPlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |