Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=trgp_PartnershipIssuersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=trgp_SeniorUnsecuredNotesDue2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=trgp_SeniorNotesDue2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=trgp_SeniorUnsecuredNotesDueMarch2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=trgp_SeniorNotesDueFebruary2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=trgp_SeniorNotesDueFebruary2027Member
Namespace Prefix:
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Debt Obligations, Senior Notes Issuances - Additional Information (Details) - Partnership Issuers [Member] - USD ($) $ in Millions	1 Months Ended
	Oct. 31, 2016	Sep. 30, 2015	Jan. 31, 2015	Oct. 31, 2014
Senior Unsecured Notes [Member] \| Senior Unsecured 4 1/8% notes due November 2019 [Member]
Debt Instrument [Line Items]
Aggregate principal amount issued				$ 800.0
Net proceeds from private placement of notes				$ 790.8
Senior Unsecured Notes [Member] \| Senior Unsecured 5% Notes due January 2018 [Member]
Debt Instrument [Line Items]
Aggregate principal amount issued			$ 1,100.0
Net proceeds from private placement of notes			$ 1,089.8
Senior Unsecured Notes [Member] \| Senior Unsecured 6 3/4% Notes due March 2024 [Member]
Debt Instrument [Line Items]
Aggregate principal amount issued		$ 600.0
Net proceeds from private placement of notes		$ 595.0
Senior Notes [Member] \| 5 1/8% Senior Notes due February 2025 [Member]
Debt Instrument [Line Items]
Aggregate principal amount issued	$ 500.0
Net proceeds from private placement of notes	$ 496.2
Price	5.125%
Maturity date	Feb. 28, 2025
Senior Notes [Member] \| 5 3/8% Senior Notes due February 2027 [Member]
Debt Instrument [Line Items]
Aggregate principal amount issued	$ 500.0
Net proceeds from private placement of notes	$ 496.2
Price	5.375%
Maturity date	Feb. 28, 2027