Employee Retirement Plans and Post-Retirement Benefit Plan - Additional Information (Detail)	12 Months Ended
	Dec. 26, 2015 USD ($) h CompensationPlan	Dec. 27, 2014 USD ($)	Dec. 28, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Unfunded projected pension benefits	$ 1,600,000	$ 1,700,000
Long-term rate of return assumption	6.50%
Debt Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Securities target allocation	35.00%
Debt Securities | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assumed average annual returns on assets	3.00%
Debt Securities | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assumed average annual returns on assets	6.00%
Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Securities target allocation	65.00%
Equity Securities | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assumed average annual returns on assets	8.00%
Equity Securities | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assumed average annual returns on assets	12.00%
Pension Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Benefit obligation, discount rate	4.50%	4.00%
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 Company, Four Zero One K Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Eligible participant required age	21 years
Eligibility timing	Eligible to participate in the plan on the first day of the first month after commencing employment
Voluntary contributions of annual compensation	60.00%
Employer matching contribution percentage	6.00%
Pension contributions	$ 3,000,000	$ 2,800,000
Non-Union Plans | Boston Beer Company, Four Zero One K Plan | Company's match for the first $1,000 of the eligible participants contribute
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer match percentage	100.00%
Contribution amount by the Company	$ 1,000
Non-Union Plans | Boston Beer Company, Four Zero One K Plan | Company's match thereafter
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer match percentage	50.00%
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") and who have completed 12 consecutive months of employment with at least 750 hours worked.
Pension contributions	$ 188,000	$ 162,000
Eligibility period	12 months
Time required for eligibility | h	750
Union Plans | Samuel Adams Pennsylvania Brewery Company , Four Zero One 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%
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	4.50%	4.00%
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 | Retiree Medical Plan | Local Union #1199 member
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Eligibility period	10 years