v3.26.3
Investments in Unconsolidated Affiliates - Activity Related to Partnership's Investments in Unconsolidated Affiliates (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Schedule Of Equity Method Investments [Line Items]        
Balance at beginning of period     $ 307.1  
Equity earnings (loss) $ 10.2 $ 6.4 26.6 $ 17.0
Balance at end of period 321.7   321.7  
Targa Resources Partners LP [Member]        
Schedule Of Equity Method Investments [Line Items]        
Balance at beginning of period     307.1 193.3
Equity earnings (loss)     26.6 17.0
Cash Distributions     (20.0) (18.7)
Contributions     8.0 [1] 124.3 [2]
Balance at end of period 321.7 315.9 321.7 315.9
Targa Resources Partners LP [Member] | Little Missouri 4 [Member]        
Schedule Of Equity Method Investments [Line Items]        
Balance at beginning of period     93.7 84.3
Equity earnings (loss)     13.9 12.6
Cash Distributions     (15.7) (15.2)
Contributions     0.3 [1] 12.7 [2]
Balance at end of period 92.2 94.4 92.2 94.4
Targa Resources Partners LP [Member] | Gulf Coast Fractionators LP [Member]        
Schedule Of Equity Method Investments [Line Items]        
Balance at beginning of period     69.2 66.4
Equity earnings (loss)     (0.7) (0.5)
Contributions     2.8 [1] 2.0 [2]
Balance at end of period 71.3 67.9 71.3 67.9
Targa Resources Partners LP [Member] | Cayenne Joint Venture [Member]        
Schedule Of Equity Method Investments [Line Items]        
Balance at beginning of period     12.3 12.3
Equity earnings (loss)     6.6 5.0
Cash Distributions     (4.3) (3.5)
Balance at end of period 14.6 13.8 14.6 13.8
Targa Resources Partners LP [Member] | Blackcomb [Member]        
Schedule Of Equity Method Investments [Line Items]        
Balance at beginning of period     131.9 30.3
Equity earnings (loss)     6.8 (0.1)
Contributions     4.9 [1] 109.6 [2]
Balance at end of period $ 143.6 $ 139.8 $ 143.6 $ 139.8
[1] Includes capitalized interest of $4.9 million related to our contributions to Blackcomb.
[2] Includes capitalized interest of $3.7 million related to our contributions to Blackcomb.