v3.26.3
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 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Earnings Per Share Reconciliation [Abstract]        
Net Income Attributable to DT Midstream $ 118 $ 115 $ 360 $ 330
Average number of common shares outstanding — basic (in shares) 102.0 101.6 102.0 101.6
Incremental shares attributable to:        
Average dilutive restricted stock units and performance share awards (in shares) 0.7 0.9 0.7 0.9
Average number of common shares outstanding — diluted (in shares) 102.7 102.5 102.7 102.5
Basic earnings per Common Share (in dollars per share) $ 1.16 $ 1.14 $ 3.54 $ 3.25
Diluted earnings per Common Share (in dollars per share) $ 1.16 $ 1.13 $ 3.51 $ 3.22