v3.26.1
FAIR VALUE MEASUREMENTS (Details) - EBP 118 - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value $ 35,400 $ 52,500
Total investments at fair value 1,432,867 1,410,609
Total    
EBP, Master Trust [Line Items]    
Total investments at fair value 1,418,631 1,395,556
Total | Common stock of International Paper Company    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 35,442 52,025
Total | Equities    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 1,014,235 1,020,038
Total | Fixed income    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 325,036 266,676
Total | Derivatives    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 209 376
Total | Cash and cash equivalents    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 8,507 17,095
Total | Interest bearing cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 3,421 6,190
Total | Non-cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 1,184 1,269
Total | Self-directed brokerage accounts    
EBP, Master Trust [Line Items]    
Investment, excluding plan interest in master trust, fair value 30,597 31,887
Active Markets for Identical Assets (Level 1)    
EBP, Master Trust [Line Items]    
Total investments at fair value 258,053 327,530
Active Markets for Identical Assets (Level 1) | Common stock of International Paper Company    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 35,442 52,025
Active Markets for Identical Assets (Level 1) | Equities    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 180,229 220,467
Active Markets for Identical Assets (Level 1) | Fixed income    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Active Markets for Identical Assets (Level 1) | Derivatives    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Active Markets for Identical Assets (Level 1) | Cash and cash equivalents    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 8,507 17,095
Active Markets for Identical Assets (Level 1) | Interest bearing cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 3,421 6,190
Active Markets for Identical Assets (Level 1) | Non-cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Active Markets for Identical Assets (Level 1) | Self-directed brokerage accounts    
EBP, Master Trust [Line Items]    
Investment, excluding plan interest in master trust, fair value 30,454 31,753
Other Observable Inputs (Level 2)    
EBP, Master Trust [Line Items]    
Total investments at fair value 1,159,967 1,067,116
Other Observable Inputs (Level 2) | Common stock of International Paper Company    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Other Observable Inputs (Level 2) | Equities    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 834,006 799,571
Other Observable Inputs (Level 2) | Fixed income    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 324,634 266,142
Other Observable Inputs (Level 2) | Derivatives    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Other Observable Inputs (Level 2) | Cash and cash equivalents    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Other Observable Inputs (Level 2) | Interest bearing cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Other Observable Inputs (Level 2) | Non-cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 1,184 1,269
Other Observable Inputs (Level 2) | Self-directed brokerage accounts    
EBP, Master Trust [Line Items]    
Investment, excluding plan interest in master trust, fair value 143 134
Significant Unobservable Inputs (Level 3)    
EBP, Master Trust [Line Items]    
Total investments at fair value 611 910
Significant Unobservable Inputs (Level 3) | Common stock of International Paper Company    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Significant Unobservable Inputs (Level 3) | Equities    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Significant Unobservable Inputs (Level 3) | Fixed income    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 402 534
Significant Unobservable Inputs (Level 3) | Derivatives    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 209 376
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Significant Unobservable Inputs (Level 3) | Interest bearing cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Significant Unobservable Inputs (Level 3) | Non-cash    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value 0 0
Significant Unobservable Inputs (Level 3) | Self-directed brokerage accounts    
EBP, Master Trust [Line Items]    
Investment, excluding plan interest in master trust, fair value 0 0
Investments measured at net asset value | Real Estate Funds    
EBP, Master Trust [Line Items]    
Investment, plan interest in master trust, fair value $ 14,236 $ 15,053
Redemption notice period 30 days 30 days