CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Trade receivables, allowances	$ 3.6	$ 0.1
Targa Resources Corp. stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	450,000,000	450,000,000
Common stock, shares issued (in shares)	236,086,963	234,792,888
Common stock, shares outstanding (in shares)	228,962,972	228,061,853
Preferred stock, par value (in dollar per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	98,800,000	98,800,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Treasury stock, shares (in shares)	7,123,991	6,731,035
Series A Preferred Stock [Member]
LIABILITIES, SERIES A PREFERRED STOCK AND OWNERS' EQUITY
Preferred Series A Liquidation Stock Percentage	9.50%	9.50%
Preferred Stock, Liquidation Preference Per Share	$ 1,000	$ 1,000
Preferred Stock, Shares Authorized	1,200,000	1,200,000
Preferred Stock, Shares Issued	919,300	919,300
Preferred Stock, Shares Outstanding	919,300	919,300