PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Additional Information (Details) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Period Increase (Decrease)	$ 44
Defined Benefit Plan, Benefit Obligation	155
Defined Benefit Plan Funded Status Period Increase (Decrease)	199
Registered Canadian Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	23
Non Registered Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	2
U.S. Non-Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	19
U.S. Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	0
U.S. and Canadian Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2018	$ 19

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of contributions expected to be received by defined benefit plan from employer in fiscal year. Excludes contributions paid by employer in current fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920

+ Details

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

- Definition

Amount of increase (decrease) in plan assets of defined benefit plan.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssetsPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan Funded Status Period Increase Decrease

+ References

No definition available.

+ Details

Name:	wy_DefinedBenefitPlanFundedStatusPeriodIncreaseDecrease
Namespace Prefix:	wy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_RetirementPlanNameAxis=wy_RegisteredPensionPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=wy_NonRegisteredPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=wy_NonQualifiedPensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanNameAxis=wy_QualifiedPensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: