v3.26.1
Investments in Unconsolidated Affiliates - Activity Related to Partnership's Investments in Unconsolidated Affiliates (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Schedule Of Equity Method Investments [Line Items]    
Balance at beginning of period $ 307.1  
Equity earnings (loss) 8.6 $ 5.5
Balance at end of period 315.0  
Targa Resources Partners LP [Member]    
Schedule Of Equity Method Investments [Line Items]    
Balance at beginning of period 307.1 193.3
Equity earnings (loss) 8.6 5.5
Cash Distributions (4.7) (4.9)
Contributions 4.0 [1] 23.8
Balance at end of period 315.0 217.7
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) 3.5 3.3
Cash Distributions (4.7) (4.9)
Contributions 0.3 [1] 4.9
Balance at end of period 92.8 87.6
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) 0.1 1.0
Contributions [1] 1.9  
Balance at end of period 71.2 67.4
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) 2.2 1.5
Balance at end of period 14.5 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) 2.8 (0.3)
Contributions 1.8 [1] 18.9
Balance at end of period $ 136.5 $ 48.9
[1] Includes capitalized interest of $1.8 million related to our contributions to Blackcomb.