An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date.

+ References

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=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Projected Benefit Obligation
-URI http://asc.fasb.org/extlink&oid=6522206

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accumulated Postretirement Benefit Obligation
-URI http://asc.fasb.org/extlink&oid=6503904

+ Details

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

- Definition

Net increase or decrease in the plan benefit obligation during the reporting period.

+ References

+ Details

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

- 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

Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 35
-Paragraph 50
-URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12355-114930

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Plan Assets
-URI http://asc.fasb.org/extlink&oid=6749337

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Plan Assets
-URI http://asc.fasb.org/extlink&oid=6520858

+ Details

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

- Definition

The amount of increase or decrease in the fair value of plan assets during the reporting period.

+ References

+ Details

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

- Definition

The funded status is measured as the difference between the fair value of plan assets and the benefit obligation. Will normally be the same as the net Defined Benefit Plan, Amounts Recognized in Balance Sheet, Total.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919

+ Details

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

- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.

+ References

No definition available.

+ Details

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

- Definition

Amount of debt and equity financial instruments classified as other and noncurrent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Additional pension benefit cost recognized as a result of an occurrence of an event that accelerates its recognition.

+ References

No definition available.

+ Details

Name:	wy_AcceleratedPensionBenefits
Namespace Prefix:	wy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Change in Fair Value of Pension Assets (%)

+ References

No definition available.

+ Details

Name:	wy_ChangeinFairValueofPensionAssets
Namespace Prefix:	wy_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Change in Projected Benefit Obligation (%)

+ References

No definition available.

+ Details

Name:	wy_ChangeinProjectedBenefitObligation
Namespace Prefix:	wy_
Data Type:	xbrli:stringItemType
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:	duration

- Details

Name:	us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Feb. 19, 2016
Defined Benefit Plan Disclosure [Line Items]
Increase (decrease) in fair value of plan assets	$ 7
Change in Fair Value of Pension Assets (%)	less than 1 percent
Increase (decrease) in fair value of plan benefit obligation	$ 1
Change in Projected Benefit Obligation (%)	less than 1 percent
Increase (decrease) in funded status of plan	$ 6
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Accelerated pension costs included in Plum Creek merger-related costs (Note 15)	0		$ 0	$ 5	$ 0
Registered Canadian Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2016				17
Non Registered Canadian Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2016				3
U.S. Non-Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2016				57
U.S. and Canadian Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2016				22
U.S. Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected contribution to benefit plans during 2016				0
Plum Creek [Member]
Defined Benefit Plan Disclosure [Line Items]
Cumulative funded status of assumed plan						$ (62)
Accelerated pension costs included in Plum Creek merger-related costs (Note 15)	0	$ 5	$ 0	5	$ 0
Plum Creek [Member] \| U.S. Non-Qualified Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Plan assets held in grantor trust	$ 47			47
Fair value of projected benefit obligation						50
Expected contribution to benefit plans during 2016				$ 38
Plum Creek [Member] \| U.S. Qualified Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets				7.00%
Fair value of plan assets						137
Fair value of projected benefit obligation						$ 149