BUSINESS SEGMENTS - Sales and Net Contribution (Charge) to Earnings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	$ 7,532	$ 6,554	$ 7,476
Net contribution (charge) to earnings	1,425	165	1,182
Timberlands
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	1,466	1,618	1,873
Real Estate & ENR
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	276	313	306
Wood Products
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	5,790	4,623	5,297
Operating segments | Timberlands
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	1,466	1,618	1,873
Net contribution (charge) to earnings	455	347	583
Operating segments | Real Estate & ENR
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	276	313	306
Net contribution (charge) to earnings	86	144	127
Operating segments | Wood Products
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	5,790	4,623	5,297
Net contribution (charge) to earnings	1,340	353	838
Unallocated Items
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	0	0	0
Net contribution (charge) to earnings	(456)	(679)	(366)
Intersegment eliminations
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	(471)	(504)	(538)
Intersegment eliminations | Timberlands
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	471	503	537
Intersegment eliminations | Real Estate & ENR
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	0	1	1
Intersegment eliminations | Wood Products
Segment Reporting, Revenue Reconciling Item
Sales to unaffiliated customers	$ 0	$ 0	$ 0