BASIS OF PRESENTATION Additional Information (Details) $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($)
Reclassification of certain tax affects from tax law changes, 2018-02	$ 253
Reclassification of accumulated unrealized gains on available-for-sale securities, ASU 2016-01	9
Adjustments for New Accounting Principle, Early Adoption
Reclassification of certain tax affects from tax law changes, 2018-02	253
Reclassification of accumulated unrealized gains on available-for-sale securities, ASU 2016-01	$ 9

Reclassification from Accumulated Other Comprehensive Income to retained earnings, adoption of accounting standard

No definition available.

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