Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Common Share [Line Items]
Net income (loss) attributable to Targa Resources Corp.		$ 71.2	$ (1,553.9)	$ (209.2)
Less: Deemed dividends on Series A Preferred			39.2	33.1
Net income (loss) attributable to common shareholders		$ (16.1)	$ (1,684.8)	$ (334.0)
Weighted average shares outstanding - basic (in shares)		228.6	232.2	232.5
Weighted average shares outstanding - diluted (in shares)		228.6	232.2	232.5
Net income (loss) per common share - basic		$ (0.07)	$ (7.26)	$ (1.44)
Net income (loss) per common share - diluted		$ (0.07)	$ (7.26)	$ (1.44)
Series A Preferred Stock [Member]
Earnings Per Common Share [Line Items]
Less: Dividends on Series A Preferred	[1]	$ 87.3	$ 91.7	$ 91.7
Less: Deemed dividends on Series A Preferred	[2]		$ 39.2	$ 33.1

[1] Includes $1.1 million attributable to the dividends paid upon the partial repurchase of Series A Preferred in December 2020.

[2] Includes $1.6 million attributable to the partial repurchase of Series A Preferred in December 2020. Refer to Note 11 – Preferred Stock.