CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Trade receivables, allowances	$ 0.1	$ 0.0
Targa Resources Corp. stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	234,293,105	233,852,810
Common stock, shares outstanding (in shares)	233,177,028	232,843,526
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)	1,116,077	1,009,284
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	965,100	965,100
Preferred Stock, Shares Outstanding	965,100	965,100