Commitments and Contingencies Disclosure [Line Items]

No definition available.

Name:	gnw_CommitmentsAndContingenciesDisclosureLineItems
Namespace Prefix:	gnw_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The value (monetary amount) of the dividends paid by a subsidiary the plaintiff sought to be returned by the parent company but was dismissed by the court.

+ References

No definition available.

+ Details

Name:	gnw_PlaintiffsMotionDismissedRelatedToDividendsPaidBySubsidiary
Namespace Prefix:	gnw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The value (monetary amount) of the dividends paid by a subsidiary the plaintiff seeks to be returned by the parent company.

+ References

No definition available.

+ Details

Name:	gnw_PlaintiffsMotionRelatedToDividendsPaidBySubsidiary
Namespace Prefix:	gnw_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Cash proceeds received by a wholly-owned subsidiary from a disposal transaction that may be restricted or limited as a result of litigation.

+ References

No definition available.

+ Details

Name:	gnw_RestrictedCashProceedsOnSalePerLitigation
Namespace Prefix:	gnw_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611

+ Details

Name:	us-gaap_FairValueDisclosureOffbalanceSheetRisksAmountLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

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

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14615-108349

+ Details

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

+ Details

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

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=gnw_CommitmentsToFundLimitedPartnershipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=gnw_CommitmentsToFundUSCommercialMortgageLoanInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=gnw_CommitmentsToFundPrivatePlacementInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=gnw_CommitmentsToFundBankLoanInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=gnw_OtherLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=gnw_LifeInsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=gnw_LitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByLiabilityClassAxis=gnw_CostOfInsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions					1 Months Ended	12 Months Ended
	Mar. 25, 2022	Aug. 11, 2021	Jul. 17, 2020	Jan. 31, 2020	Jan. 31, 2021	Dec. 31, 2019	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 11, 2019
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet risk							$ 1,409		$ 1,185
Commitments to Fund Limited Partnerships
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet risk							1,409
Commitments to fund U.S. commercial mortgage loan investments
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet risk							64
Commitments to Fund Private Placement Investments
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet risk							24
Commitments to Fund Bank Loan Investments
Commitments and Contingencies Disclosure [Line Items]
Off-balance sheet risk							$ 75
Other Litigation
Commitments and Contingencies Disclosure [Line Items]
Plaintiff's Motion Dismissed				$ 395
Loss Contingency, Damages Sought		$ 5			$ 5
Plaintiffs' motion				$ 15		$ 410
Restricted cash proceeds on sale per litigation										$ 450
Life Insurance [Member] \| Litigation \| Cost of Insurance
Commitments and Contingencies Disclosure [Line Items]
Loss Contingency, Damages Sought			$ 5		$ 5
Contingent liability								$ 25
Litigation Settlement, Amount Awarded to Other Party	$ 25