Partnership Units and Related Matters - Summary of Distributions Declared or Paid by the Partnership (Details) - Distributions Paid [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Distributions Made To Members Or Limited Partners [Abstract]
Distributions payable date	May 11, 2018	Feb. 12, 2018
Total Distributions	$ 229.7	$ 228.5
Distributions to Targa Resources Corp.	$ 226.9	$ 225.7