Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended												12 Months Ended
	Dec. 26, 2020 USD ($)	Sep. 26, 2020 USD ($)	Jun. 27, 2020 USD ($)	Mar. 28, 2020 USD ($)	Dec. 28, 2019 USD ($)		Sep. 28, 2019 USD ($)	[1]	Jun. 29, 2019 USD ($)	[1]	Mar. 30, 2019 USD ($)	[1]	Dec. 26, 2020 USD ($) customer	Dec. 28, 2019 USD ($) customer	Dec. 29, 2018 USD ($) customer	Dec. 31, 2018
Organization And Summary Of Significant Accounting Policies [Line Items]
Income tax expense													$ 52,270,000	$ 34,329,000	$ 23,623,000
Net effect of COVID-19 on revenue, cost of goods sold and operating expense	$ 42,125,000	$ 101,781,000	$ 78,769,000	$ 21,532,000	$ 17,702,000	[1]	$ 59,836,000		$ 37,932,000		$ 29,443,000		$ 244,207,000	$ 144,912,000	$ 115,881,000
Sales to foreign distributors as a percentage of total sales	4.00%				4.00%								4.00%	4.00%	4.00%	4.00%
Number of individual customers represented more than ten percent of revenues | customer													0	0	0
Number of individual customer accounted for more than ten percent of account receivable balance | customer													0	0
Inventory on hand, purchase commitment	$ 285,000.0												$ 285,000.0
Provision for excess or expired inventory													11,300,000	$ 8,100,000	$ 4,200,000
Property, plant and equipment, net, excluding capital leased assets	623,100,000												623,100,000
Impairment of assets													4,466,000	911,000	652,000
Goodwill	112,529,000				$ 112,529,000								112,529,000	112,529,000	$ 3,683,000
Intangible assets	103,930,000				104,272,000								103,930,000	104,272,000
Decrease in refundable deposits for lost kegs and pallets													(400,000)	(800,000)
Decrease in gross property, plant and equipment													(800,000)	(1,300,000)
Decrease in property, plant and equipment related accumulated depreciation													(800,000)	(1,300,000)
Refundable deposits on kegs and pallets	$ 15,500,000				$ 19,500,000								$ 15,500,000	$ 19,500,000
Sales to domestic distributors as a percentage of total sales	95.00%				95.00%								95.00%	95.00%	95.00%
Sales to retail locations as a percentage of total sales	1.00%				1.00%								1.00%	1.00%	1.00%
Deferred Revenue, Current	$ 13,522,000				$ 6,984,000								$ 13,522,000	$ 6,984,000
Stale Beer Reserve	3,100,000				1,800,000								3,100,000	1,800,000
Provision for stale beer													8,400,000	4,400,000	$ 2,700,000
Advertising, promotional and selling expenses													447,568,000	355,613,000	304,853,000
Advertising and sales promotional expenditures													211,200,000	177,200,000	145,100,000
Reduction in federal excise taxes													11,900,000	8,900,000
Shipping costs													97,600,000	69,100,000	61,800,000
Stock-based compensation													15,282,000	12,337,000	10,035,000
ASU 2017-04
Organization And Summary Of Significant Accounting Policies [Line Items]
Goodwill impairment if fair value exceeds carrying amount													0
Distributors
Organization And Summary Of Significant Accounting Policies [Line Items]
Amounts paid to distributors													59,300,000	43,900,000	34,500,000
Advertising and sales promotional expenditures													25,700,000	31,300,000	21,000,000.0
Reduction in revenue related to advertising, promotional and selling expenses													23,100,000	21,600,000	13,900,000
Customers programs and incentives
Organization And Summary Of Significant Accounting Policies [Line Items]
Advertising, promotional and selling expenses													85,000,000.0	75,200,000	55,500,000
Kegs
Organization And Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net, excluding capital leased assets	300,000				500,000								300,000	500,000
Boston Beer Company Reporting Unit
Organization And Summary Of Significant Accounting Policies [Line Items]
Goodwill	$ 112,500,000				$ 112,500,000								112,500,000	112,500,000
Property, Plant and Equipment
Organization And Summary Of Significant Accounting Policies [Line Items]
Impairment of assets													$ 4,400,000	$ 900,000	$ 700,000
COVID-19 Pandemic
Organization And Summary Of Significant Accounting Policies [Line Items]
Decreased percentage of shipments													3.00%	11.00%
Net effect of COVID-19 on revenue, cost of goods sold and operating expense													$ 16,000,000.0

[1] During the second, third and fourth quarter of 2019, the Company recorded $1.9 million, $5.9 million and $2.1 million in non-reoccurring transaction fees related to the Dogfish Head Transaction, respectively.