CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net income (loss)	$ (11.2)	$ (155.1)	$ 148.6	$ (195.0)
Commodity hedging contracts:
Other comprehensive income (loss), pre-tax	(115.7)	(104.7)	(119.7)	(8.3)
Other comprehensive income (loss), related income tax	27.8	39.7	28.9	3.1
Other comprehensive income (loss), after tax	(87.9)	(65.0)	(90.8)	(5.2)
Comprehensive income (loss)	(99.1)	(220.1)	57.8	(200.2)
Less: Comprehensive income (loss) attributable to noncontrolling interests	12.5	12.5	40.4	34.3
Comprehensive income (loss) attributable to Targa Resources Corp.	(111.6)	(232.6)	17.4	(234.5)
Commodity Contracts [Member]
Commodity hedging contracts:
Change in fair value, pre-tax	(139.6)	(106.8)	(178.0)	(10.5)
Change in fair value, related income tax	32.3	40.6	43.0	4.1
Change in fair value, after tax	(107.3)	(66.2)	(135.0)	(6.4)
Settlements reclassified to revenues, pre-tax	23.9	2.1	58.3	2.2
Settlements reclassified to revenues, related income tax	(4.5)	(0.9)	(14.1)	(1.0)
Settlements reclassified to revenues, after tax	$ 19.4	$ 1.2	$ 44.2	$ 1.2