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
Mar. 31, 2026
Mar. 31, 2025
Basic and Diluted Earnings per Common Share    
Net Income Attributable to DT Midstream $ 130 $ 108
Average number of common shares outstanding — basic (in shares) 101.8 101.4
Incremental shares attributable to:    
Average dilutive restricted stock units and performance share awards (in shares) 0.9 1.1
Average number of common shares outstanding — diluted (in shares) 102.7 102.5
Basic earnings per Common Share (in dollars per share) $ 1.28 $ 1.07
Diluted earnings per Common Share (in dollars per share) $ 1.27 $ 1.06