Debt Obligations - Range of Interest Rates and Weighted Average Interest Rate Incurred on Variable Rate Debt Obligations (Details)	Sep. 30, 2018
TRC Revolver [Member]
Debt Instrument [Line Items]
Weighted average interest rate incurred	3.60%
TRP Revolver [Member]
Debt Instrument [Line Items]
Weighted average interest rate incurred	3.80%
Targa Resources Partners LP [Member] | Accounts Receivable Securitization Facility [Member]
Debt Instrument [Line Items]
Weighted average interest rate incurred	2.90%
Minimum [Member] | TRC Revolver [Member]
Debt Instrument [Line Items]
Range of interest rates incurred	3.30%
Minimum [Member] | TRP Revolver [Member]
Debt Instrument [Line Items]
Range of interest rates incurred	3.40%
Minimum [Member] | Targa Resources Partners LP [Member] | Accounts Receivable Securitization Facility [Member]
Debt Instrument [Line Items]
Range of interest rates incurred	2.60%
Maximum [Member] | TRC Revolver [Member]
Debt Instrument [Line Items]
Range of interest rates incurred	4.00%
Maximum [Member] | TRP Revolver [Member]
Debt Instrument [Line Items]
Range of interest rates incurred	5.50%
Maximum [Member] | Targa Resources Partners LP [Member] | Accounts Receivable Securitization Facility [Member]
Debt Instrument [Line Items]
Range of interest rates incurred	3.20%