Investments in Unconsolidated Affiliates - Activity Related to Partnership's Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		$ 586.5
Equity earnings (loss)		9.1		$ (23.9)		$ 72.6
Balance at end of period		131.3		586.5
Targa Resources Partners LP [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		586.5		714.0		738.7
Equity earnings (loss)		9.1		(23.9)		72.6
Cash Distributions		(29.0)		(104.2)		(100.0)
Disposition/ Consolidation		(436.8)
Contributions		1.5		0.6		2.7
Balance at end of period		131.3		586.5		714.0
Targa Resources Partners LP [Member] | GCX [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		421.0		435.2		447.5
Equity earnings (loss)		5.7		63.4		66.3
Cash Distributions		(14.3)		(78.1)		(81.3)
Disposition/ Consolidation		(412.4)
Contributions				0.5		2.7
Balance at end of period				421.0		435.2
Targa Resources Partners LP [Member] | Little Missouri 4 [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		98.1		104.7		103.7
Equity earnings (loss)		5.5		10.9		10.8
Cash Distributions		(12.9)		(17.5)		(9.8)
Balance at end of period		90.7		98.1		104.7
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		89.6
Equity earnings (loss)		(0.6)	[1]	(57.0)		(8.9)
Cash Distributions		(0.8)	[1]	(1.0)		(0.9)
Disposition/ Consolidation	[1]	(20.5)
Contributions				0.1
Balance at end of period				21.9	[1]	79.8
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		44.8
Equity earnings (loss)		(0.3)	[1]	(35.0)		(4.8)
Cash Distributions				(0.4)		(0.4)
Disposition/ Consolidation	[1]	(3.9)
Balance at end of period				4.2	[1]	39.6
Targa Resources Partners LP [Member] | Gulf Coast Fractionators LP [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		28.8	[2]	38.5	[2]	37.2
Equity earnings (loss)		(3.2)	[2]	(8.6)	[2]	2.9
Cash Distributions				(1.1)	[2]	(1.6)
Contributions	[2]	1.5
Balance at end of period	[2]	27.1		28.8		38.5
Targa Resources Partners LP [Member] | Cayenne Joint Venture [Member]
Schedule Of Equity Method Investments [Line Items]
Balance at beginning of period		12.5		16.2		15.9
Equity earnings (loss)		2.0		2.4		6.3
Cash Distributions		(1.0)		(6.1)		(6.0)
Balance at end of period		$ 13.5		$ 12.5		$ 16.2

[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, GCF 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 GCF. The facility is expected to be operational during the first quarter of 2024.