Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands	Aug. 16, 2021	Jul. 30, 2021	Mar. 22, 2021	Oct. 26, 2020	Oct. 21, 2019	Jan. 01, 2022	Jan. 02, 2021	Dec. 28, 2019
Business Acquisition [Line Items]
Goodwill						$ 157,374	$ 155,617	$ 157,916
Weight Watchers of Maine, Inc.
Business Acquisition [Line Items]
Business acquisition, aggregate purchase price	$ 2,250
Business acquisition, cash payment	1,999
Business acquisition, assumed net liabilities	26
Business acquisition, cash in reserves	225
Goodwill	2,153
The WW Group, Inc.
Business Acquisition [Line Items]
Business acquisition, aggregate purchase price			$ 17,500
Business acquisition, cash payment		$ 6,450	8,255
Business acquisition, assumed net liabilities			495
Business acquisition, cash in reserves			2,300
Business acquisition, purchase price allocation, inventories			162
Business acquisition, purchase price allocation, property and equipment			41
Business acquisition, purchase price allocation, other assets			4
The WW Group Co.
Business Acquisition [Line Items]
Business acquisition, aggregate purchase price			3,114
Business acquisition, cash payment			2,605
Business acquisition, cash in reserves			599
Business acquisition, purchase price allocation, inventories			6
Business acquisition, purchase price allocation, property and equipment			25
Business acquisition, purchase price allocation, other assets			1
Business acquisition, assumed net assets			90
Weight Watchers of Arizona, Inc. and Weight Watchers Imperial County, Inc.
Business Acquisition [Line Items]
Business acquisition, aggregate purchase price				$ 10,000
Business acquisition, cash payment				10,037
Business acquisition, purchase price allocation, inventories				84
Business acquisition, purchase price allocation, property and equipment				131
Business acquisition, assumed net assets				37
Business acquisition, purchase price allocation, current assets, other				12
Weight Watchers of Las Vegas, Inc.
Business Acquisition [Line Items]
Business acquisition, aggregate purchase price					$ 4,500
Business acquisition, cash payment					4,060
Business acquisition, assumed net liabilities					55
Goodwill					4,111
Business acquisition, cash in reserves					385
Franchise Rights | Weight Watchers of Maine, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, indefinite lived intangible assets	41
Franchise Rights | The WW Group, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, indefinite lived intangible assets			16,885
Franchise Rights | The WW Group Co.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, indefinite lived intangible assets			3,040
Franchise Rights | Weight Watchers of Arizona, Inc. and Weight Watchers Imperial County, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, indefinite lived intangible assets				9,546
Franchise Rights | Weight Watchers of Las Vegas, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, indefinite lived intangible assets					118
Customer Relationship | Weight Watchers of Maine, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, finite lived intangible assets	$ 56
Customer Relationship | The WW Group, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, finite lived intangible assets			408
Customer Relationship | The WW Group Co.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, finite lived intangible assets			$ 42
Customer Relationship | Weight Watchers of Arizona, Inc. and Weight Watchers Imperial County, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, finite lived intangible assets				$ 227
Customer Relationship | Weight Watchers of Las Vegas, Inc.
Business Acquisition [Line Items]
Business acquisition, purchase price allocation, finite lived intangible assets					$ 271