FAIR VALUE OF FINANCIAL INSTRUMENTS Estimated Fair Values and Carrying Values of Long-Term Debt (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Long-term Debt, Excluding Current Maturities	$ 8,013	$ 4,787
Note payable to Timberland Venture (Note 10)	830	0
Total Debt	8,843	4,787
Fair Value, Inputs, Level 2
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Total Debt	9,979	5,517
Note Payable to Timberland Venture [Member]
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Note payable to Timberland Venture (Note 10)	830	0
Note Payable to Timberland Venture [Member] \| Fair Value, Inputs, Level 2
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Note Payable to Timberland Venture, Fair Value Disclosure	845	0
Fixed interest rate [Member]
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Long-term Debt, Excluding Current Maturities	6,066	4,238
Fixed interest rate [Member] \| Fair Value, Inputs, Level 2
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Long-term Debt, Fair Value	7,184	4,967
Variable interest rate [Member]
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Long-term Debt, Excluding Current Maturities	1,947	549
Variable interest rate [Member] \| Fair Value, Inputs, Level 2
FAIR VALUE OF FINANCIAL INSTRUMENTS [Line Items]
Long-term Debt, Fair Value	$ 1,950	$ 550

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13476-108611

+ Details

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

- Definition

Portion of the carrying amount as of the balance sheet date of obligations due all related parties that is payable after one year or beyond the normal operating cycle if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.23)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ 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 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Total debt, including long-term debt and note payable to related party.

+ References

No definition available.

+ Details

Name:	wy_TotalDebt
Namespace Prefix:	wy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=wy_NotePayabletoTimberlandVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wy_FixedinterestrateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=wy_VariableinterestrateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: