Debt Obligations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
Schedule of Debt Instruments [Line Items]
Long-term debt	$ 2,522.4		$ 2,475.3
Irrevocable Standby Letters of Credit [Member]
Schedule of Debt Instruments [Line Items]
Letters of credit outstanding	53.2		45.3
Senior unsecured notes due 2017 [Member]
Range of interest rates and weighted average interest rate [Abstract]
Per Annum Interest Rate (in hundredths)	11.25%
Senior unsecured notes due 2018 [Member]
Range of interest rates and weighted average interest rate [Abstract]
Per Annum Interest Rate (in hundredths)	7.875%
Senior unsecured notes due 2021 [Member]
Range of interest rates and weighted average interest rate [Abstract]
Per Annum Interest Rate (in hundredths)	6.875%
Senior unsecured notes due 2022 [Member]
Range of interest rates and weighted average interest rate [Abstract]
Per Annum Interest Rate (in hundredths)	6.375%
Senior unsecured notes due 2023 [Member]
Range of interest rates and weighted average interest rate [Abstract]
Per Annum Interest Rate (in hundredths)	5.25%
TRC Senior secured credit facility [Member] | Secured Debt [Member] | Irrevocable Standby Letters of Credit [Member]
Schedule of Debt Instruments [Line Items]
Letters of credit outstanding	0	[1]	0	[1]
Partnership's Senior secured credit facility [Member] | Secured Debt [Member] | Irrevocable Standby Letters of Credit [Member]
Schedule of Debt Instruments [Line Items]
Letters of credit outstanding	53.2	[2]	45.3	[2]
Partnership's accounts receivable securitization facility [Member] | Accounts Receivable Securitization [Member]
Range of interest rates and weighted average interest rate [Abstract]
Range of Interest Rates Incurred, Maximum (in hundredths)	0.90%
Weighted Average Interest Rate Incurred (in hundredths)	0.90%
Parent Company excluding Partnership [Member] | TRC senior secured revolving credit facility due 2017 [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	72.0	[1]	82.0	[1]
Maturity date	Oct. 01, 2017
Parent Company excluding Partnership [Member] | TRP senior secured revolving credit facility due 2015 [Member]
Range of interest rates and weighted average interest rate [Abstract]
Range of Interest Rates Incurred, Minimum (in hundredths)	2.90%
Range of Interest Rates Incurred, Maximum (in hundredths)	3.00%
Weighted Average Interest Rate Incurred (in hundredths)	3.00%
Parent Company excluding Partnership [Member] | Senior unsecured notes due 2017 [Member] | Secured Debt [Member]
Range of interest rates and weighted average interest rate [Abstract]
Revolving credit facility	78.0
Available capacity under revolving credit facility	150.0
Targa Resources Partners LP [Member] | Accounts receivable securitization facility [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	111.4	[3],[4]	0	[3],[4]
Maturity date	Jan. 01, 2014
Targa Resources Partners LP [Member] | TRC senior secured revolving credit facility due 2017 [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	565.0	[2],[3]	620.0	[2],[3]
Maturity date	Oct. 01, 2017
Targa Resources Partners LP [Member] | TRC senior secured revolving credit facility due 2017 [Member] | Secured Debt [Member]
Range of interest rates and weighted average interest rate [Abstract]
Revolving credit facility	1,200.0
Available capacity under revolving credit facility	581.8
Targa Resources Partners LP [Member] | Senior unsecured notes due 2017 [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	72.7	[3]	72.7	[3]
Unamortized discount	(2.4)	[3]	(2.5)	[3]
Maturity date	Jul. 15, 2017
Targa Resources Partners LP [Member] | Senior unsecured notes due 2018 [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	250.0	[3]	250.0	[3]
Maturity date	Oct. 15, 2018
Targa Resources Partners LP [Member] | Senior unsecured notes due 2021 [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	483.6	[3]	483.6	[3]
Unamortized discount	(29.9)	[3]	(30.5)	[3]
Maturity date	Feb. 01, 2021
Targa Resources Partners LP [Member] | Senior unsecured notes due 2022 [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	400.0	[3]	400.0	[3]
Maturity date	Aug. 01, 2022
Targa Resources Partners LP [Member] | Senior unsecured notes due 2023 [Member]
Schedule of Debt Instruments [Line Items]
Long-term debt	600.0	[3]	600.0	[3]
Maturity date	May 01, 2023
Targa Resources Partners LP [Member] | Senior unsecured notes due 2023 [Member] | Accounts Receivable Securitization [Member]
Range of interest rates and weighted average interest rate [Abstract]
Aggregated principal amount of the new note	$ 200
Targa Resources Partners LP [Member] | Partnership's Senior secured credit facility [Member]
Range of interest rates and weighted average interest rate [Abstract]
Range of Interest Rates Incurred, Minimum (in hundredths)	1.90%
Range of Interest Rates Incurred, Maximum (in hundredths)	4.50%
Weighted Average Interest Rate Incurred (in hundredths)	2.20%

[1] As of March 31, 2013, $78.0 million of TRC's $150.0 million credit facility was available.

[2] As of March 31, 2013, availability under the Partnership's $1.2 billion senior secured revolving credit facility was $581.8 million.

[3] 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.

[4] All amounts outstanding under the Partnership’s Securitization Facility are reflected as long-term debt in our balance sheet to the extent that the Partnership has the ability and intent to fund the Securitization Facility’s borrowing with availability under the Partnership’s long-term Senior Secured Credit Facility (the “TRP Revolver”).