Condensed Parent Only Financial Statements, Condensed Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Other long-term assets	$ 81.7	$ 96.1
Total assets	15,208.2	15,875.7
LIABILITIES, SERIES A PREFERRED STOCK AND OWNERS' EQUITY
Accrued current liabilities	272.2	186.4
Other long-term liabilities	301.6	309.1
Targa Resources Corp. stockholders' equity	2,011.8	2,653.9
Total liabilities, Series A Preferred Stock and owners' equity	15,208.2	15,875.7
Parent Company [Member]
ASSETS
Investment in consolidated subsidiaries	2,746.2	3,507.2
Deferred income taxes	65.1	59.7
Debt issuance costs	1.7	2.9
Other long-term assets	8.8	9.4
Total assets	2,821.8	3,579.2
LIABILITIES, SERIES A PREFERRED STOCK AND OWNERS' EQUITY
Accrued current liabilities	30.8	30.5
Long-term debt		555.0
Other long-term liabilities	29.5	38.4
Series A Preferred, net of discount	749.7	301.4
Targa Resources Corp. stockholders' equity	2,011.8	2,653.9
Total liabilities, Series A Preferred Stock and owners' equity	$ 2,821.8	$ 3,579.2