v3.26.1
STOCKHOLDERS' EQUITY Part 1 (Details) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Dec. 31, 2024
Stockholders' Equity Note [Abstract]        
Dividends, Per Share $ 0.84 $ 0.83    
Stockholders' Equity Attributable to Parent $ 6,009   $ 5,961  
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest 6,086 $ 5,944 6,037 $ 5,852
Net earnings attributable to Eastman 107 182    
Net earnings attributable to noncontrolling interest 0 1    
Net earnings including noncontrolling interest 107 183    
Cash dividends declared (98) (96)    
Other Comprehensive Income (Loss) 19 (7) 154  
Share-based Compensation Expense 27 23    
Stock Option Exercises 1 2    
Other (6) (12)    
Distributions to Noncontrolling Interest (1) (1)    
Noncontrolling interest 77 73 76 73
Common Stock [Member]        
Stockholders' Equity Attributable to Parent 2 2 2 2
Net earnings attributable to Eastman 0 0    
Cash dividends declared 0 0    
Other Comprehensive Income (Loss) 0 0    
Share-based Compensation Expense 0 0    
Stock Option Exercises 0 0    
Other 0 0    
Distributions to Noncontrolling Interest 0 0    
Additional Paid-in Capital [Member]        
Stockholders' Equity Attributable to Parent 2,520 2,476 2,500 2,463
Net earnings attributable to Eastman 0 0    
Cash dividends declared 0 0    
Other Comprehensive Income (Loss) 0 0    
Share-based Compensation Expense 27 23    
Stock Option Exercises 1 2    
Other (8) (12)    
Distributions to Noncontrolling Interest 0 0    
Retained Earnings [Member]        
Stockholders' Equity Attributable to Parent 10,114 10,099 10,105 10,013
Net earnings attributable to Eastman 107 182    
Cash dividends declared (98) (96)    
Other Comprehensive Income (Loss) 0 0    
Share-based Compensation Expense 0 0    
Stock Option Exercises 0 0    
Other 0 0    
Distributions to Noncontrolling Interest 0 0    
Accumulated Other Comprehensive Income (Loss) [Member]        
Stockholders' Equity Attributable to Parent (141) (321) (160) (314)
Net earnings attributable to Eastman 0 0    
Cash dividends declared 0 0    
Other Comprehensive Income (Loss) 19 (7)    
Share-based Compensation Expense 0 0    
Stock Option Exercises 0 0    
Other 0 0    
Distributions to Noncontrolling Interest 0 0    
Treasury Stock, Common        
Stockholders' Equity Attributable to Parent (6,486) (6,385) (6,486) (6,385)
Net earnings attributable to Eastman 0 0    
Cash dividends declared 0 0    
Other Comprehensive Income (Loss) 0 0    
Share-based Compensation Expense 0 0    
Stock Option Exercises 0 0    
Other 0 0    
Distributions to Noncontrolling Interest 0 0    
Parent [Member]        
Stockholders' Equity Attributable to Parent 6,009 5,871 $ 5,961 $ 5,779
Net earnings attributable to Eastman 107 182    
Cash dividends declared (98) (96)    
Other Comprehensive Income (Loss) 19 (7)    
Share-based Compensation Expense 27 23    
Stock Option Exercises 1 2    
Other (8) (12)    
Distributions to Noncontrolling Interest 0 0    
Noncontrolling Interest [Member]        
Net earnings attributable to noncontrolling interest 0 1    
Cash dividends declared 0 0    
Other Comprehensive Income (Loss) 0 0    
Share-based Compensation Expense 0 0    
Stock Option Exercises 0 0    
Other 2 0    
Distributions to Noncontrolling Interest $ (1) $ (1)