Investments in Unconsolidated Affiliates - Activity Related to Partnership's Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		$ 131.3
Equity earnings (loss)		9.0	$ 9.1		$ (23.9)
Balance at end of period		146.3	131.3
Targa Resources Partners LP [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		131.3	586.5		714.0
Equity earnings (loss)		9.0	9.1		(23.9)
Cash Distributions		(18.6)	(29.0)		(104.2)
Disposition/ Consolidation			(436.8)
Contributions		24.6	1.5		0.6
Balance at end of period		146.3	131.3		586.5
Targa Resources Partners LP [Member] | GCX [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period			421.0		435.2
Equity earnings (loss)			5.7		63.4
Cash Distributions			(14.3)		(78.1)
Disposition/ Consolidation			(412.4)
Contributions					0.5
Balance at end of period					421.0
Targa Resources Partners LP [Member] | Little Missouri 4 [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		90.7	98.1		104.7
Equity earnings (loss)		7.7	5.5		10.9
Cash Distributions		(11.3)	(12.9)		(17.5)
Balance at end of period		87.1	90.7		98.1
Targa Resources Partners LP [Member] | T2 Eagle Ford
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period			21.9	[1]	79.8
Equity earnings (loss)			(0.6)	[1]	(57.0)
Cash Distributions			(0.8)	[1]	(1.0)
Disposition/ Consolidation	[1]		(20.5)
Contributions					0.1
Balance at end of period	[1]				21.9
Targa Resources Partners LP [Member] | T2 La Salle
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period			4.2	[1]	39.6
Equity earnings (loss)			(0.3)	[1]	(35.0)
Cash Distributions					(0.4)
Disposition/ Consolidation	[1]		(3.9)
Balance at end of period	[1]				4.2
Targa Resources Partners LP [Member] | Gulf Coast Fractionators LP [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period	[2]	27.1	28.8		38.5
Equity earnings (loss)	[2]	(4.1)	(3.2)		(8.6)
Cash Distributions	[2]	(2.0)			(1.1)
Contributions	[2]	24.6	1.5
Balance at end of period	[2]	45.6	27.1		28.8
Targa Resources Partners LP [Member] | Cayenne Joint Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		13.5	12.5		16.2
Equity earnings (loss)		5.4	2.0		2.4
Cash Distributions		(5.3)	(1.0)		(6.1)
Balance at end of period		$ 13.6	$ 13.5		$ 12.5

[1] Following the closing of the South Texas Acquisition in April 2022, the T2 Joint Ventures are 100% owned and consolidated by Targa.

[2] In January 2021, the GCF facility was temporarily idled and Targa assumed operatorship in the first half of 2021. In January 2023, we reached an agreement with our partners to reactivate the GCF facility. The facility is expected to be operational in the second quarter of 2024.