Partnership Units and Related Matters - Summary of Distributions Declared and Paid by the Partnership (Details) - Distributions Paid [Member] - USD ($) $ in Millions	3 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Distributions Made To Members Or Limited Partners [Abstract]
Distributions payable date	Nov. 13, 2019	Aug. 13, 2019	Apr. 05, 2019	Feb. 13, 2019
Total Distributions	$ 242.1	$ 242.4	$ 437.8	$ 241.3
Distributions to Targa Resources Corp.	$ 239.3	$ 239.6	$ 435.0	$ 238.5

Date of distribution for distribution of cash or unit to limited partner of limited partnership (LP), in CCYY-MM-DD format.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

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