v3.26.1
EARNINGS PER SHARE AND DIVIDENDS - Reconciliation of Basic and Diluted Earnings Per Share Calculation (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Basic and Diluted Earnings per Common Share        
Net Income Attributable to DT Midstream $ 112 $ 107 $ 242 $ 215
Average number of common shares outstanding — basic (in shares) 102.0 101.6 102.0 101.5
Incremental shares attributable to:        
Average dilutive restricted stock units and performance share awards (in shares) 0.6 0.9 0.7 1.0
Average number of common shares outstanding — diluted (in shares) 102.6 102.5 102.7 102.5
Basic earnings per Common Share (in dollars per share) $ 1.10 $ 1.05 $ 2.37 $ 2.12
Diluted earnings per Common Share (in dollars per share) $ 1.09 $ 1.04 $ 2.36 $ 2.10