Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2011	Jun. 25, 2011	Feb. 17, 2012 Common Class A	Feb. 17, 2012 Common Class B
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2011
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Trading Symbol	SAM
Entity Registrant Name	BOSTON BEER CO INC
Entity Central Index Key	0000949870
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Public Float		$ 763,363,977
Entity Common Stock, Shares Outstanding			8,765,306	4,107,355