SHAREHOLDERS' INTEREST - Changes in Amounts Included in Our Accumulated Other Comprehensive Loss (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassification of certain effects due to tax law changes			$ 253
Reclassification of accumulated unrealized gains on available-for-sale securities			(9)
Pension
Accumulated Other Comprehensive Income Loss [Line Items]
Defined Benefit Plan, Plan Assets, Payment for Settlement	$ 253	$ 455	200
Reclassification of certain effects due to tax law changes	$ 0	$ 0	$ (246)

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.

No definition available.

+ Details

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

- Definition

Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(8)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

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

- Definition

Reclassification from accumulated other comprehensive income to retained earnings, adoption of accounting standard.

+ References

No definition available.

+ Details

Name:	wy_ReclassificationFromAccumulatedOtherComprehensiveIncomeToRetainedEarningsAdoptionOfAccountingStandard
Namespace Prefix:	wy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Reclassification of accumulated unrealized gains on available for sale securities adoption of accounting standard.

+ References

No definition available.

+ Details

Name:	wy_ReclassificationOfAccumulatedUnrealizedGainsOnAvailableForSaleSecuritiesAdoptionOfAccountingStandard
Namespace Prefix:	wy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_StatementEquityComponentsAxis=wy_AccumulatedPensionPlansDefinedBenefitPlansAdjustmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: