Debt Obligations - Summary Of Debt Obligations (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Current Obligations of the Partnership [Abstract]
Current debt	[1]	$ 300.0	$ 350.0
Long-term [Abstract]
Long-term debt		5,064.2	4,703.0
Long-term debt including Unamortized premium(discount) and Debt issuance costs		5,093.0	4,733.0
Debt issuance costs, net of amortization		(28.8)	(30.0)
Total debt obligations		5,364.2	5,053.0
Letters of credit outstanding		25.9	27.2
TRP Senior Secured Revolving Credit Facility due October 2020 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1],[2]	380.0	20.0
Senior Unsecured Notes [Member] | Senior Unsecured 4 1/8% notes due November 2019 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1]	749.4	749.4
Senior Unsecured Notes [Member] | Senior Unsecured 5 1/4% Notes due May 2023 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1]	559.6	559.6
Senior Unsecured Notes [Member] | Senior Unsecured 4 1/4% Notes due November 2023 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1]	583.9	583.9
Senior Unsecured Notes [Member] | Senior Unsecured 6 3/4% Notes due March 2024 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1]	580.1	580.1
Senior Unsecured Notes [Member] | Senior Unsecured 5 1/8% Notes due February 2025 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1]	500.0	500.0
Senior Unsecured Notes [Member] | Senior Unsecured 5 3/8% Notes due February 2027 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1]	500.0	500.0
Senior Unsecured Notes [Member] | Senior Unsecured 5% Notes due January 2028 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Long-term debt	[1]	750.0	750.0
Senior Unsecured Notes [Member] | Targa Pipeline Partners LP [Member] | Senior Unsecured 4 3/4% Notes due November 2021 [Member]
Long-term [Abstract]
Long-term debt		6.5	6.5
Senior Unsecured Notes [Member] | Targa Pipeline Partners LP [Member] | Senior Unsecured 5 7/8% Notes due August 2023 [Member]
Long-term [Abstract]
Long-term debt		48.1	48.1
Unamortized premium		0.4	0.4
Secured Debt [Member] | TRC Senior Secured Revolving Credit Facility [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Letters of credit outstanding	[3]	0.0	0.0
Revolving Credit Facility [Member] | TRC Senior Secured Revolving Credit Facility due February 2020 [Member]
Long-term [Abstract]
Long-term debt	[3]	435.0	435.0
Revolving Credit Facility [Member] | TRP Senior Secured Revolving Credit Facility due October 2020 [Member] | Targa Resources Partners LP [Member]
Long-term [Abstract]
Letters of credit outstanding	[2]	$ 25.9	$ 27.2

[1] While we consolidate the debt of the Partnership in our financial statements, we do not have the obligation to make interest payments or debt payments with respect to the debt of the Partnership.

[2] As of March 31, 2018, availability under the Partnership’s $1.6 billion senior secured revolving credit facility (“TRP Revolver”) was $1,194.1 million.

[3] As of March 31, 2018, availability under TRC’s $670.0 million senior secured revolving credit facility (“TRC Revolver”) was $235.0 million.