The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI https://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

+ Details

Name:	us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=126966197&loc=d3e6613-128477

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126975305&loc=d3e6927-128479

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI https://asc.fasb.org/extlink&oid=126966197&loc=d3e6578-128477

+ Details

Name:	us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 55
-Paragraph 24
-URI https://asc.fasb.org/extlink&oid=122137925&loc=d3e14258-109268

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(15))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13854-109267

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 55
-Paragraph 24
-URI https://asc.fasb.org/extlink&oid=122137925&loc=d3e14258-109268

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillImpairmentLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

+ Details

Name:	us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of fair value of reporting unit in excess of carrying amount.

+ References

No definition available.

+ Details

Name:	us-gaap_ReportingUnitPercentageOfFairValueInExcessOfCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Franchise agreement period.

+ References

No definition available.

+ Details

Name:	ww_FranchiseAgreementPeriod
Namespace Prefix:	ww_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Goodwill and intangible assets disclosure.

+ References

No definition available.

+ Details

Name:	ww_GoodwillAndIntangibleAssetsDisclosureLineItems
Namespace Prefix:	ww_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of franchise rights acquired.

+ References

No definition available.

+ Details

Name:	ww_PercentageOfFranchiseRightsAcquired
Namespace Prefix:	ww_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Reporting unit, percentage of goodwill held.

+ References

No definition available.

+ Details

Name:	ww_ReportingUnitPercentageOfGoodwillHeld
Namespace Prefix:	ww_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ww_KurboHealthIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ww_KurboIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_FranchiseRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ReportingUnitAxis=ww_OtherUnitsOfAccountMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_CA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_GB
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_AU
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_NZ
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=ww_OtherCountriesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=ww_AllReportingUnitsExceptForRepublicOfIrelandMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_IE
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_GoodwillMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_FranchiseRightsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Franchise Rights Acquired, Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($)				3 Months Ended		6 Months Ended
	May 08, 2022	May 09, 2021	Aug. 10, 2018	Jul. 02, 2022	Jul. 03, 2021	Jul. 02, 2022	Jul. 03, 2021	Jan. 01, 2022	Jan. 02, 2021
Goodwill And Intangible Assets Disclosure [Line Items]
Franchise right maturity period						7 years
Net book value of goodwill				$ 159,932,000		$ 159,932,000		$ 157,374,000	$ 155,617,000
Goodwill impairment	$ 0	$ 0				1,101,000
Finite-lived intangible assets, aggregate amortization expense				8,761,000	$ 8,035,000	$ 16,935,000	$ 16,033,000
Kurbo Health, Inc
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of goodwill			$ 1,101,000
Net purchase price			$ 3,063,000
Kurbo, Inc
Goodwill And Intangible Assets Disclosure [Line Items]
Goodwill impairment				$ 1,101,000
Franchise Rights
Goodwill And Intangible Assets Disclosure [Line Items]
Indefinite-lived intangible assets, impairment charges		$ 0
Franchise Rights \| Other Units of Account
Goodwill And Intangible Assets Disclosure [Line Items]
Indefinite-lived intangible assets, impairment charges	$ 0
Percentage of franchise rights acquired				2.20%		2.20%
United States
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of goodwill				$ 104,019,000		$ 104,019,000
United States \| Franchise Rights
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of franchise rights acquired				$ 698,383,000		$ 698,383,000
Percentage of franchise rights acquired				92.70%		92.70%
Percentage of estimated fair value in excess of carrying amount	15.00%
Canada
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of goodwill				$ 41,605,000		$ 41,605,000
Canada \| Franchise Rights
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of franchise rights acquired				34,556,000		$ 34,556,000
Indefinite-lived intangible assets, impairment charges				$ 24,485,000
Percentage of franchise rights acquired				4.60%		4.60%
United Kingdom \| Franchise Rights
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of franchise rights acquired				$ 10,899,000		$ 10,899,000
Australia \| Franchise Rights
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of franchise rights acquired				6,125,000		6,125,000
New Zealand \| Franchise Rights
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of franchise rights acquired				3,574,000		$ 3,574,000
Indefinite-lived intangible assets, impairment charges				$ 834,000
Percentage of franchise rights acquired				0.50%		0.50%
Other Countries
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of goodwill				$ 14,308,000		$ 14,308,000
All Reporting Units Except for Republic of Ireland
Goodwill And Intangible Assets Disclosure [Line Items]
Percentage of goodwill held				97.30%		97.30%
Republic of Ireland
Goodwill And Intangible Assets Disclosure [Line Items]
Net book value of goodwill				$ 4,265,000		$ 4,265,000
Percentage of goodwill held				2.70%		2.70%
Percentage of estimated fair value in excess of carrying amount	14.00%
Minimum \| Franchise Rights \| Other Units of Account
Goodwill And Intangible Assets Disclosure [Line Items]
Percentage of estimated fair value in excess of carrying amount	100.00%
Minimum \| All Reporting Units Except for Republic of Ireland \| Goodwill
Goodwill And Intangible Assets Disclosure [Line Items]
Percentage of estimated fair value in excess of carrying amount	35.00%
Franchise Rights \| Maximum
Goodwill And Intangible Assets Disclosure [Line Items]
Finite-lived intangible assets, estimated useful life (in years)						1 year